Preparation of Diazoalkane Complexes of Ruthenium and Their

Article pubs.acs.org/Organometallics

Preparation of Diazoalkane Complexes of Ruthenium and Their Cyclization Reactions with Alkenes and Alkynes Gabriele Albertin,*,† Stefano Antoniutti,† Alessandra Botter,† Jesús Castro,‡ and Mattia Giacomello† †

Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca’ Foscari Venezia, Dorsoduro 2137, 30123 Venezia, Italy Departamento de Quı ́mica Inorgánica, Facultade de Quı ́mica, Edificio de Ciencias Experimentais, Universidade de Vigo, 36310 Vigo, Galicia, Spain

‡

S Supporting Information *

ABSTRACT: The diazoalkane complexes [Ru(η5-C5H5)(N2CAr1Ar2)(PPh3)(L)]BPh4 (1−5: Ar1 = Ar2 = Ph (a), Ar1 = Ph and Ar2 = p-tolyl (b), Ar1Ar2 = C12H8 (c), Ar1 = Ph and Ar2 = PhCO (d); L = PPh3 (1), P(OMe)3 (2), P(OEt)3 (3), PPh(OEt)2 (4), ButNC (5)) were prepared by allowing the chloro compounds RuCl(η5-C5H5)(PPh3)(L) to react with the diazoalkanes Ar1Ar2CN2 in ethanol. Treatment of complexes 1−5 with ethylene (CH2CH2) under mild conditions (1 atm, room temperature) led not only to the η2-ethylene complexes [Ru(η 5-C5 H5)(η2-CH2CH2)(PPh 3)(L)]BPh4 (10−14) but also to dipolar (3 + 2) cycloaddition, affording the 4,5-dihydro-3H-pyrazole derivatives [Ru(η5-C5H5){η1-N NC(Ar1Ar2)CH2CH2}(PPh3)(L)]BPh4 (6−9). Acrylonitrile (CH2C(H)CN) reacted with diazoalkane complexes 2 and 3 to give the 1H-pyrazoline derivatives [Ru(η5-C5H5){η1-NC(CN)CH2C(Ar1Ar2)NH}(PPh3)(L)]BPh4 (19, 20). However, reactions with propylene (CH2C(H)CH3), maleic anhydride (ma, CHCHCO(O)CO) and dimethyl maleate (dmm, CH3OCOCHCHOCOCH3) led to the η2-alkene complexes [Ru(η5-C5H5)(η2-R1CHCHR2)(PPh3)(L)]BPh4 (17−22). Treatment of the diazoalkane complexes 1 and 2 with acetylene CHCH under mild conditions (1 atm, room temperature) led to dipolar cycloaddition, affording the 3H-pyrazole complexes [Ru(η5-C5H5){η1-NNC(Ar1Ar2)CHCH}(PPh3) {P(OMe)3}]BPh4 (24), whereas reactions with the terminal alkynes PhCCH and ButCCH gave the vinylidene derivatives [Ru(η5-C5H5){CC(H)R}(PPh3){P(OMe)3}]BPh4 (25, 26). The alkyl propiolates HCCCOOR1 (R1 = Me, Et) also reacted with complexes 2 to give the 3H-pyrazole complexes [Ru(η5-C5H5){η1-NNC(Ar1Ar2)C(COOR1)CH}(PPh3){P(OMe)3}]BPh4 (27, 28). The complexes were characterized by spectroscopy and by X-ray crystal structure determinations of [Ru(η5-C5H5){η1-NC(CN)CH2C(Ph)(p-tolyl)NH}(PPh3){P(OMe)3}]BPh4 (19b), [Ru(η5-C5H5){η2-CHCHCO(O)CO}(PPh3){P(OMe)3}]BPh4 (21), and [Ru(η5-C5H5){η1-NNC(C12H8)CHCH}(PPh3){P(OMe)3}]BPh4 (24c).

■

[M]−N2,8f N−N bond cleavage,8k and reduction of the coordinated N2CAr1Ar2 ligand.8i However, no example of cyclization of coordinated diazoalkane had ever been reported until we found10 that the half-sandwich complexes [Ru(η5-C5H5)(N2CAr1Ar2)(PPh3){P(OR)3}]BPh4 can undergo unprecedented (3 + 2) cycloaddition of a metal-bonded diazoalkane to ethylene, yielding 4,5-dihydro-3H-pyrazole derivatives. These interesting preliminary results prompted us to extend our research and study to activated alkenes and alkynes, as well as to the influence of ancillary ligands on the cyclization reaction. This paper reports full details of our study of the synthesis of diazoalkane complexes of ruthenium and the (3 + 2) cycloaddition

INTRODUCTION The reactivity of diazoalkanes Ar1Ar2CN2 toward transitionmetal complexes has attracted longstanding interest1,2 in the synthesis of carbene complexes [M]CAr1Ar2,2 often used as olefin metathesis catalysts.3 The diazoalkane can also cooordinate to the metal center, yielding the metal complexes [M]− N2CAr1Ar2, which may be of interest as models for understanding N2 coordination and functionalization.4,5 A number of diazoalkane complexes of several metals have been prepared,6−9 displaying a variety of coordination modes, as shown in Chart 1. In the mononuclear complexes, either the η1-end-on (type I) or η2-NN side-on (type II) coordination mode is commonly observed, whereas the two bridging modes III and IV are reported in dinuclear derivatives. Instead, relatively few data have been reported on the reactivity of coordinate diazoalkane,1,6−9 including the formation of dinitrogen complexes © 2014 American Chemical Society

Received: May 6, 2014 Published: July 2, 2014 3570

dx.doi.org/10.1021/om500481d | Organometallics 2014, 33, 3570−3582

Organometallics

Article

4.63 (s, 5H, Cp), 2.42 (s, 3H, CH3); 31P{1H} NMR (CD2Cl2, 20 °C) δ 39.68 (s). Anal. Calcd for C79H67BN2P2Ru (1218.22): C, 77.89; H, 5.54; N, 2.30. Found: C, 77.68; H, 5.43; N, 2.41. ΛM = 53.6 Ω−1 mol−1 cm2. [Ru(η5-C5H5)(N2CAr1Ar2)(PPh3)(L)]BPh4 (2−4). In a 25 mL threenecked round-bottomed flask were placed solid samples of the appropriate chloro complex RuCl(η5-C5H5)(PPh3)(L) (0.3 mmol), an excess of the diazoalkane Ar1Ar2CN2 (0.9 mmol), an excess of NaBPh4 (0.6 mmol, 0.205 g), and 10 mL of ethanol. The reaction mixture was stirred for 24 h, and the solid that formed was filtered and crystallized from CH2Cl2/EtOH. A further amount of solid complex could be recovered by concentration of the mother liquor and cooling to −25 °C: yield ≥70%. 2a (L = P(OMe)3, Ar1 = Ar2 = Ph): IR (KBr, cm−1) νN2 1967 (m); 1H NMR (CD2Cl2, 20 °C) δ 7.48−6.87 (m, 45H, Ph), 5.00 (d, 5H, Cp), 3.31 (d, 9H, CH3); 31P{1H} NMR (CD2Cl2, 20 °C) δ AB spin syst, δA 144.47, δB 47.76, JAB = 63.2 Hz. Anal. Calcd for C63H59BN2O3P2Ru (1065.98): C, 70.98; H, 5.58; N, 2.63. Found: C, 71.17; H, 5.65; N, 2.54. ΛM = 54.3 Ω−1 mol−1 cm2. 2b (L = P(OMe)3, Ar1 = Ph, Ar2 = p-tolyl): IR (KBr, cm−1) νN2 1959 (m); 1H NMR (CD2Cl2, 20 °C) δ 7.53−6.86 (m, 44H, Ph), 4.99 (d, 5H, Cp), 3.32 (d, 9H, CH3 phos), 2.39 (s, 3H, CH3 p-tolyl); 31P{1H} NMR (CD2Cl2, 20 °C) δ AB, δA 144.7, δB 47.9, JAB = 63.5 Hz. Anal. Calcd for C64H61BN2O3P2Ru (1080.01): C, 71.17; H, 5.69; N, 2.59. Found: C, 71.30; H, 5.59; N, 2.72. ΛM = 53.2 Ω−1 mol−1 cm2. 2c (L = P(OMe)3, Ar1Ar2 = C12H8): IR (KBr, cm−1) νN2 1961 (m); 1H NMR (CD2Cl2, 20 °C) δ 8.00−6.59 (m, 43H, Ph), 5.11 (d, 5H, Cp), 3.45 (d, 9H, CH3); 31P{1H} NMR (CD2Cl2, 20 °C) δ AB, δA 142.0, δB 47.2, JAB = 60.8 Hz. Anal. Calcd for C63H57BN2O3P2Ru (1063.97): C, 71.12; H, 5.40; N, 2.63. Found: C, 71.30; H, 5.51; N, 2.55. ΛM = 55.0 Ω−1 mol−1 cm2. 2d (L = P(OMe)3, Ar1 = Ph, Ar2 = PhCO): IR (KBr, cm−1) νN2 1963 (m), νCO 1614 (s); 1H NMR (CD2Cl2, 20 °C) δ 7.55−6.87 (m, 45H, Ph), 5.01 (d, 5H, Cp), 3.38 (d, 9H, CH3); 31P{1H} NMR (CD2Cl2, 20 °C) δ AB, δA 139.63, δB 45.66, JAB = 60.4 Hz. Anal. Calcd for C64H59BN2O4P2Ru (1093.99): C, 70.26; H, 5.44; N, 2.56. Found: C, 70.11; H, 5.36; N, 2.64. ΛM = 52.6 Ω−1 mol−1 cm2. 3a (L = P(OEt)3, Ar1 = Ar2 = Ph): IR (KBr, cm−1) νN2 1961 (m); 1H NMR (CD2Cl2, 20 °C) δ 7.48−6.87 (m, 45H, Ph), 4.97 (d, 5H, Cp), 3.76 (m, 6H, CH2), 1.09 (t, 9H, CH3); 31P{1H} NMR (CD2Cl2, 20 °C) δ AB, δA 138.88, δB 47.43, JAB = 63.2 Hz. Anal. Calcd for C66H65BN2O3P2Ru (1108.06): C, 71.54; H, 5.91; N, 2.53. Found: C, 71.38; H, 6.00; N, 2.46. ΛM = 56.4 Ω−1 mol−1 cm2. 3b (L = P(OEt)3, Ar1 = Ph, Ar2 = p-tolyl): IR (KBr, cm−1) νN2 1961 (m); 1H NMR (CD2Cl2, 20 °C) δ 7.50−6.87 (m, 44H, Ph), 4.95 (d, 5H, Cp), 3.77 (m, 6H, CH2), 2.39 (s, 3H, CH3 p-tolyl), 1.10 (t, 9H, CH3 phos); 31P{1H} NMR (CD2Cl2, 20 °C) δ AB spin syst, δA 139.2, δB 47.6, JAB = 63.2 Hz; 13C{1H} NMR (CD2Cl2, 20 °C) δ 165−122 (m, Ph), 86.8 (s, Cp), 63.4 (d, CH2), 21.3 (s, CH3 p-tolyl), 16.2 (d, CH3 phos). Anal. Calcd for C67H67BN2O3P2Ru (1122.09): C, 71.72; H, 6.02; N, 2.50. Found: C, 71.57; H, 5.91; N, 2.58. ΛM = 53.8 Ω−1 mol−1 cm2. 3c (L = P(OEt)3, Ar1Ar2 = C12H8): IR (KBr, cm−1) νN2 1959 (m); 1H NMR (CD2Cl2, 20 °C) δ 7.99−6.58 (m, 43H, Ph), 5.09 (s, 5H, Cp), 3.82 (m, 6H, CH2), 1.08 (t, 9H, CH3); 31P{1H} NMR (CD2Cl2, 20 °C) δ AB spin syst, δA 136.4, δB 46.6, JAB = 60.8 Hz. Anal. Calcd for C66H63BN2O3P2Ru (1106.05): C, 71.67; H, 5.74; N, 2.53. Found: C, 71.53; H, 5.59; N, 2.46. ΛM = 52.8 Ω−1 mol−1 cm2. 3d (L = P(OEt)3, Ar1 = Ph, Ar2 = PhCO): IR (KBr, cm−1) νN2 1964 (w), νCO 1612 (s); 1H NMR (CD2Cl2, 20 °C) δ 7.53−6.87 (m, 45H, Ph), 4.98 (s, 5H, Cp), 3.68 (m, 6H, CH2), 1.11 (t, 9H, CH3); 31P{1H} NMR (CD2Cl2, 20 °C) δ AB, δA 133.22, δB 45.10, JAB = 60.8 Hz. Anal. Calcd for C67H65BN2O4P2Ru (1136.07): C, 70.83; H, 5.77; N, 2.47. Found: C, 70.63; H, 5.66; N, 2.58. ΛM = 50.9 Ω−1 mol−1 cm2. 4a (L = PPh(OEt)2, Ar1 = Ar2 = Ph): IR (KBr, cm−1) νN2 1942 (m); 1 H NMR (CD2Cl2, 20 °C) δ 7.53−6.86 (m, 50H, Ph), 4.74 (s, 5H, Cp), 3.74 (qnt), 3.60, 3.46 (m) (4H, CH2), 1.15, 1.10 (t, 6H, CH3); 31P{1H} NMR (CD2Cl2, 20 °C) δ AB, δA 164.72, δB 46.25, JAB = 49.8 Hz. Anal. Calcd for C70H65BN2O2P2Ru (1140.11): C, 73.74; H, 5.75; N, 2.46. Found: C, 73.52; H, 5.84; N, 2.38. ΛM = 51.6 Ω−1 mol−1 cm2. 4b (L = PPh(OEt)2, Ar1 = Ph, Ar2 = p-tolyl): IR (KBr, cm−1) νN2 1931 (m); 1H NMR (CD2Cl2, 20 °C) δ 7.52−6.87 (m, 49H, Ph), 4.74

Chart 1. Coordination Modes of Diazoalkane

of the cooordinate diazoalkane to several alkenes and alkynes, yielding 3H-pyrazole and 1H-pyrazoline derivatives.

■

EXPERIMENTAL SECTION

General Comments. All synthetic work was carried out under an appropriate atmosphere (Ar, N2) using standard Schlenk techniques or in an inert-atmosphere drybox. All solvents were dried over appropriate drying agents, degassed on a vacuum line, and distilled into vacuum-tight storage flasks. RuCl3·3H2O was a Pressure Chemical Co. (USA) product, phenyldiethoxyphosphine PPh(OEt)2 was prepared by the method of Rabinowitz and Pellon,11 phosphites P(OMe)3 and P(OEt)3 and tert-butyl isocyanide were Aldrich products used as received, diazoalkanes were prepared following the known method,12 and other reagents were purchased from commercial sources in the highest available purity and used as received. Infrared spectra were recorded on a Perkin-Elmer Spectrum-One FT-IR spectrophotometer. NMR spectra (1H, 13C, 31P) were obtained on an Bruker AVANCE 300 spectrometer at temperatures varying between +20 and −80 °C, unless otherwise noted. 1H and 13C spectra are referred to internal tetramethylsilane. 31 1 P{ H} chemical shifts are reported with respect to 85% H3PO4, with downfield shifts considered positive. COSY, HMQC, and HMBC NMR experiments were performed with standard programs. The iNMR software package13 was used to treat NMR data. The conductivity of 10−3 mol dm−3 solutions of the complexes in CH3NO2 at 25 °C was measured on a Radiometer CDM 83 instrument. Elemental analyses were determined in the Microanalytical Laboratory of the Dipartimento di Scienze del Farmaco, University of Padova, Padova, Italy. Synthesis of the Complexes. The compounds RuCl(η5-C5H5)(PPh3)2 and (RuCl(η5-C5H5)(PPh3)(L) (L = P(OMe)3, P(OEt)3, PPh(OEt)2] were prepared following the methods previously reported.14,15 RuCl(η5-C5H5)(PPh3)(ButNC). An equimolar amount of tert-butyl isocyanide (31 μL, 0.275 mmol) was added to a solution of RuCl(η5-C5H5)(PPh3)2 (0.275 mmol, 0.200 g) in benzene (8 mL), and the reaction mixture was refluxed for 2 h. The solvent was removed under reduced pressure to give an oil, which was triturated with ethanol (3 mL). When the resulting solution was cooled to −25 °C, a yellow solid slowly separated out, which was dried under vacuum: yield ≥85%. IR (KBr, cm−1) νCN 2109 (s); 1H NMR (CD2Cl2, 20 °C) δ 7.60−7.36 (m, 15H, Ph), 4.56 (s, 5H, Cp), 1.22 (s, 9H, CH3); 31P{1H} NMR (CD2Cl2, 20 °C) δ 53.74 (s). Anal. Calcd for C28H29ClNPRu (547.03): C, 61.48; H, 5.34; Cl, 6.48; N, 2.56. Found: C, 61.31; H, 5.23; Cl, 6.65; N, 2.46. [Ru(η5-C5H5){N2C(Ph)p-tolyl}(PPh3)2]BPh4 (1b). In a 25 mL threenecked round-bottomed flask were placed solid samples of RuCl(η5C5H5)(PPh3)2 (0.10 g, 0.138 mmol), an excess of (p-tolyl)(Ph)CN2 (0.42 mmol, 87 mg), an excess of NaBPh4 (0.28 mmol, 96 mg), 5 mL of ethanol, and enough dichloromethane to give a clear solution (2−3 mL). The reaction mixture was stirred for 6 h and then the solvent removed under reduced pressure to give an oil, which was triturated with ethanol (8 mL). A reddish brown solid complex slowly separated out, which was filtered and crystallized from CH2Cl2/EtOH: yield ≥65%. IR (KBr, cm−1) νN2 1955 (m); 1H NMR (CD2Cl2, 20 °C) δ 7.45−6.82 (m, 59H, Ph), 3571

dx.doi.org/10.1021/om500481d | Organometallics 2014, 33, 3570−3582

Organometallics

Article

145.46, δB 47.20, JAB = 69.3 Hz. Anal. Calcd for C65H63BN2O3P2Ru (1094.04): C, 71.36; H, 5.80; N, 2.56. Found: C, 71.44; H, 5.71; N, 2.45. ΛM = 54.5 Ω−1 mol−1 cm2. 6b (L = P(OMe)3, Ar1 = Ph, Ar2 = p-tolyl): 1H NMR (CD2Cl2, 20 °C) δ 7.50−6.75 (m, 44H, Ph), 4.70, 4.69 (s, 5H, Cp), 4.43 (m, 2H, H5), 3.36, 3.34 (d, 9H, CH3 phos), 2.33 (s, 3H, CH3 p-tolyl), 2.22 (m, 2H, H4); 31P{1H} NMR (CD2Cl2, 20 °C) δ AB, δA 145.5, δB 48.2, JAB = 69.3; δA 145.6, δB 48.3, JAB = 69.3 Hz; 13C{1H} NMR (CD2Cl2, 20 °C) δ 165− 122 (m, Ph), 97.5 (s, C3), 87.84, 87.79 (s, C5), 84.36, 84.32 (s, Cp), 53.4, 53.1 (s, CH3 phos), 33.99, 33.94 (s, C4), 21.14, 21.11 (s, CH3 p-tolyl). Anal. Calcd for C66H65BN2O3P2Ru (1108.06): C, 71.54; H, 5.91; N, 2.53. Found: C, 71.67; H, 5.79; N, 2.45. ΛM = 52.5 Ω−1 mol−1 cm2. 6c (L = P(OMe)3, Ar1Ar2 = C12H8): 1H NMR (CD2Cl2, 20 °C) δ 7.77−6.47 (m, 43H, Ph), 4.84 (m, 2H, H5), 4.78 (s, 5H, Cp), 3.40 (d, 9H, CH3), 2.23 (t, 2H, H4); 31P{1H} NMR (CD2Cl2, 20 °C) δ AB, δA 145.5, δB 47.5, JAB = 69.3 Hz; 13C{1H} NMR (CD2Cl2, 20 °C) δ 165−121 (m, Ph), 98.32 (s, C3), 88.95 (s, C5), 84.32 (s, Cp), 53.2 (s, CH3), 30.59 (s, C4). Anal. Calcd for C65H61BN2O3P2Ru (1092.02): C, 71.49; H, 5.63; N, 2.57. Found: C, 71.32; H, 5.55; N, 2.66. ΛM = 51.9 Ω−1 mol−1 cm2. 7b (L = P(OEt)3, Ar1 = Ph, Ar2 = p-tolyl): 1H NMR (CD2Cl2, 20 °C) δ 7.50−6.86 (m, 44H, Ph), 4.66, 4.65 (s, 5H, Cp), 4.31 (m, 2H, H5), 3.83 (m, 6H, CH2 phos), 2.35, 2.32 (s, 3H, CH3 p-tolyl), 2.12 (m, 2H, H4), 1.16, 1.09 (t, 9H, CH3 phos); 31P{1H} NMR (CD2Cl2, 20 °C) δ AB, δA 140.35, δB 48.50, JAB = 66.8; δA 140.15, δB 48.32, JAB = 66.8 Hz. Anal. Calcd for C69H71BN2O3P2Ru (1150.14): C, 72.06; H, 6.22; N, 2.44. Found: C, 71.89; H, 6.11; N, 2.46. ΛM = 54.5 Ω−1 mol−1 cm2. 7c (L = P(OEt)3, Ar1Ar2 = C12H8): 1H NMR (CD2Cl2, 20 °C) δ 7.84− 6.32 (m, 43H, Ph), 4.89, 4.88 (t, 2H, H5), 4.75 (s, 5H, Cp), 3.69−3.10 (m, 6H, CH2 phos), 2.20 (t, 2H, H4), 1.03 (t, 9H, CH3); 31P{1H} NMR (CD2Cl2, 20 °C) δ AB, δA 139.6, δB 47.4, JAB = 68.1 Hz. Anal. Calcd for C68H67BN2O3P2Ru (1134.10): C, 72.02; H, 5.95; N, 2.47. Found: C, 72.18; H, 5.84; N, 2.40. ΛM = 52.3 Ω−1 mol−1 cm2. 8b (L = PPh(OEt)2, Ar1 = Ph, Ar2 = p-tolyl): 1H NMR (CD2Cl2, 20 °C) δ 7.58−6.87 (m, 49H, Ph), 4.55, 4.35 (m, 2H, H5), 4.49, 4.47 (s, 5H, Cp), 3.67, 3.65 (m, 4H, CH2 phos), 2.38, 2.24 (t, 2H, H4), 2.35, 2.32 (s, 3H, CH3 p-tolyl), 1.23, 1.18, 1.16, 1.01 (t, 6H, CH3 phos); 31P{1H} NMR (CD2Cl2, 20 °C) δ AB, δA 165.30, δB 46.97, JAB = 55.9; δA 165.20, δB 46.66, JAB = 57.1 Hz. Anal. Calcd for C73H71BN2O2P2Ru (1182.19): C, 74.17; H, 6.05; N, 2.37. Found: C, 74.32; H, 6.00; N, 2.44. ΛM = 51.5 Ω−1 mol−1 cm2. 8c (L = PPh(OEt)2, Ar1Ar2 = C12H8): 1H NMR (CD2Cl2, 20 °C) δ 9.08−6.88 (m, 48H, Ph), 4.90 (m, 2H, H5), 4.60 (s, 5H, Cp), 3.67, 3.47 (m, 4H, CH2 phos), 2.24, 2.16 (m, 2H, H4), 1.26, 1.16 (t, 6H, CH3 phos); 31P{1H} NMR (CD2Cl2, 20 °C) δ AB, δA 165.20, δB 44.65, JAB = 54.7 Hz. Anal. Calcd for C72H67BN2O2P2Ru (1166.14): C, 74.16; H, 5.79; N, 2.40. Found: C, 74.03; H, 5.91; N, 2.33. ΛM = 54.4 Ω−1 mol−1 cm2.

(s, 5H, Cp), 3.76 (qnt), 3.60, 3.48 (m) (4H, CH2), 2.42 (s, 3H, CH3 p-tolyl), 1.17, 1.02 (t, 6H, CH3 phos); 31P{1H} NMR (CD2Cl2, 20 °C) δ AB spin syst, δA 165.10, δB 46.45, JAB = 52.0 Hz; 13C{1H} NMR (CD2Cl2, 20 °C) δ 165−122 (m, Ph), 87.17 (s, Cp), 84.22 (s, CN2), 64.66 (t, CH2), 21.18 (s, CH3 p-tolyl), 16.32 (t, CH3 phos). Anal. Calcd for C71H67BN2O2P2Ru (1154.13): C, 73.89; H, 5.85; N, 2.43. Found: C, 73.70; H, 5.74; N, 2.38. ΛM = 53.2 Ω−1 mol−1 cm2. 4c (L = PPh(OEt)2, Ar1Ar2 = C12H8): IR (KBr, cm−1) νN2 1967 (m); 1 H NMR (CD2Cl2, 20 °C) δ 8.00−6.62 (m, 48H, Ph), 4.88 (s, 5H, Cp), 3.96, 3.87, 3.67, 3.51 (m, 4H, CH2), 1.16, 0.90 (t, 6H, CH3); 31P{1H} NMR (CD2Cl2, 20 °C) δ AB spin syst, δA 162.85, δB 45.90, JAB = 49.8 Hz; 13C{1H} NMR (CD2Cl2, 20 °C) δ 165−120 (m, Ph), 88.39 (s, Cp), 65.29 (t, CH2), 16.32, 16.09 (d, CH3). Anal. Calcd for C70H63BN2O2P2Ru (1138.09): C, 73.87; H, 5.58; N, 2.46. Found: C, 73.99; H, 5.46; N, 2.53. ΛM = 50.4 Ω−1 mol−1 cm2. 4d (L = PPh(OEt)2, Ar1 = Ph, Ar2 = PhCO): IR (KBr, cm−1) νCO 1609 (s); 1H NMR (CD2Cl2, 20 °C) δ 7.55−6.86 (m, 50H, Ph), 4.75 (s, 5H, Cp), 3.78, 3.64, 3.48 (m, 4H, CH2), 1.19, 1.07 (t, 6H, CH3); 31P{1H} NMR (CD2Cl2, 20 °C) δ AB, δA 159.30, δB 44.73, JAB = 49.8 Hz. Anal. Calcd for C71H65BN2O3P2Ru (1168.12): C, 73.00; H, 5.61; N, 2.40. Found: C, 72.82; H, 5.54; N, 2.31. ΛM = 53.7 Ω−1 mol−1 cm2. [Ru(η5-C5H5)(N2CAr1Ar2)(PPh3)(ButNC)]BPh4 (5). In a 25 mL three-necked round-bottomed flask were placed 55 mg of RuCl(η5C5H5)(PPh3)(ButNC) (0.1 mmol), an excess of the appropriate diazoalkane Ar1Ar2CN2 (0.3 mmol), an excess of NaBPh4 (0.2 mmol, 68 mg), and 4 mL of ethanol. The reaction mixture was stirred for 24 h, and then the solvent was removed under reduced pressure to give an oil, which was triturated with ethanol (2 mL). An orange solid slowly separated out, which was filtered and crystallized from CH2Cl2/EtOH: yield ≥55%. 5a (Ar1 = Ar2 = Ph): IR (KBr, cm−1) νCN 2133 (s), νN2 1900 (m); 1H NMR (CD2Cl2, 20 °C) δ 7.48−6.87 (m, 45H, Ph), 5.04 (s, 5H, Cp), 1.16 (s, 9H, CH3); 31P{1H} NMR (CD2Cl2, 20 °C) δ 51.41(s); 13C{1H} NMR (CD2Cl2, 20 °C) δ 165−122 (m, Ph), 86.49 (s, Cp), 85.98 (s, CN2), 59.22 (s, C But), 30.46 (s, CH3 But). Anal. Calcd for C65H59BN3PRu (1025.04): C, 76.16; H, 5.80; N, 4.10. Found: C, 76.01; H, 5.70; N, 4.18. ΛM = 53.4 Ω−1 mol−1 cm2. 5b (Ar1 = Ph, Ar2 = p-tolyl): IR (KBr, cm−1) νCN 2130 (s), νN2 1905 (s); 1H NMR (CD2Cl2, 20 °C) δ 7.45−6.87 (m, 44H, Ph), 5.03 (s, 5H, Cp), 2.40 (s, 3H, CH3 p-tolyl), 1.16 (s, 9H, CH3 But); 31P{1H} NMR (CD2Cl2, 20 °C) δ 51.51(s); 13C{1H} NMR (CD2Cl2, 20 °C) δ 165− 122 (m, Ph), 86.43 (s, Cp), 85.9 (br, CN2), 59.20 (s, C(CH3)3), 30.48 (s, CH3 But), 21.33 (s, CH3 p-tolyl). Anal. Calcd for C66H61BN3PRu (1039.07): C, 76.29; H, 5.92; N, 4.04. Found: C, 76.43; H, 5.86; N, 3.96. ΛM = 54.7 Ω−1 mol−1 cm2. 5c (Ar1Ar2 = C12H8): IR (KBr, cm−1) νCN 2140 (s), νN2 1939 (s); 1H NMR (CD2Cl2, 20 °C) δ 8.20−6.87 (m, 43H, Ph), 5.15 (s, 5H, Cp), 1.17 (s, 9H, CH3); 31P{1H} NMR (CD2Cl2, 20 °C) δ 50.23(s). Anal. Calcd for C65H57BN3PRu (1023.02): C, 76.31; H, 5.62; N, 4.11. Found: C, 76.15; H, 5.69; N, 4.03. ΛM = 53.1 Ω−1 mol−1 cm2.

[Ru(η5-C5H5){η1-NNC(Ph)(p-tolyl)CH2CH2}(PPh3)(ButNC)]BPh4 (9b). This complex was prepared exactly like the related phosphane compounds 6b−8b using a reaction time of 20 h: yield ≥65%; IR (KBr, cm−1) νCN 2123 (s); 1H NMR (CD2Cl2, 20 °C) δ 7.50−6.86 (m, 44H, Ph), 4.74, 4.72 (s, 5H, Cp), 4.19 (m, 2H, H5), 2.86 (t, 2H, H4), 2.34 (s, 3H, CH3 p-tolyl), 1.29 (s, 9H, CH3 But); 31P{1H} NMR (CD2Cl2, 20 °C) δ 51.88, 51.69 (s). Anal. Calcd for C68H65BN3PRu (1067.12): C, 76.54; H, 6.14; N, 3.94. Found: C, 76.36; H, 6.19; N, 4.02. ΛM = 50.8 Ω−1 mol−1 cm2. [Ru(η5-C5H5)(η2-CH2CH2)(PPh3)2]BPh4 (10). In a 25 mL threenecked round-bottomed flask were placed a solid sample of the chloro complex RuCl(η5-C5H5)(PPh3)2 (0.109 g, 0.15 mmol), an excess of NaBPh4 (0.3 mmol, 0.103 g), and 4 mL of ethanol. The reaction mixture was stirred under an ethylene atmosphere (1 atm) for 24 h, and then the pale yellow solid that formed was filtered and crystallized from CH2Cl2 and ethanol: yield ≥90%; 1H NMR (CD2Cl2, 20 °C) δ 7.48−6.81 (m, 50H, Ph), 4.66 (s, 5H, Cp), 2.97 (t, 4H, CH2CH2, 3J1H31P = 3.45 Hz); 31P{1H} NMR (CD2Cl2, 20 °C) δ 41.70 (s); 13C{1H} NMR (CD2Cl2, 20 °C) δ 165−122 (m, Ph), 88.03 (s, Cp), 43.59 (s, CH2 CH2). Anal. Calcd for C67H59BP2Ru (1038.01): C, 77.52; H, 5.73. Found: C, 77.38; H, 5.80. ΛM = 52.9 Ω−1 mol−1 cm2.

[Ru(η5-C5H5){η1-NNC(Ar1Ar2)CH2CH2}(PPh3)(L)]BPh4 (6−8).

A solution of the appropriate diazoalkane complex [Ru(η5-C5H5)(N2CAr1Ar2)(PPh3)(L)]BPh4 (2−4; 0.1 mmol) in CH2Cl2 (10 mL) was allowed to stand under ethylene (1 atm) for 24 h. The solvent was removed under reduced pressure to give an oil, which was triturated with ethanol (2 mL). An orange solid slowly separated out, which was filtered and fractionally crystallized by diffusion of ethanol into a dichloromethane solution of the complex. The first crystals obtained were the 4,5-dihydro-3H-pyrazole complexes 6−8: yield ≥75%. 6a (L = P(OMe)3, Ar1 = Ar2 = Ph): 1H NMR (CD2Cl2, 20 °C) δ 7.48− 6.81 (m, 45H, Ph), 4.70 (s, 5H, Cp), 4.45 (m, 2H, H5), 3.35 (d, 9H, CH3 phos), 2.32, 2.19 (m, 2H, H4); 31P{1H} NMR (CD2Cl2, 20 °C) δ AB, δA 3572

dx.doi.org/10.1021/om500481d | Organometallics 2014, 33, 3570−3582

Organometallics

Article

[Ru(η5-C5H5)(η2-CH2CH2)(PPh3)(L)]BPh4 (11−14).

Method 1. A solution of the appropriate diazoalkane complex [Ru(η5C5H5)(N2CAr1Ar2)(PPh3)(L)]BPh4 (2, 3; 0.15 mmol) in 10 mL of CH2Cl2 was placed into an autoclave, which was then pressurized with propylene (7 atm), and the mixture was stirred at room temperature for 24 h. The solvent was removed under vacuum and the oil obtained treated with ethanol (3 mL) containing NaBPh4 (0.15 mmol, 51 mg). A yellow solid slowly separated out, which was filtered and fractionally crystallized from CH2Cl2 and ethanol: yield ≥40%. Method 2. In a 25 mL three-necked round-bottomed flask were placed a solid sample of the chloro complex RuCl(η5-C5H5)(PPh3)(L) (0.15 mmol), an excess of NaBPh4 (0.3 mmol, 0.103 g), and 4 mL of ethanol. The reaction mixture was stirred under a propylene atmosphere (1 atm) for 24 h, and then the solid that formed was filtered and crystallized from CH2Cl2 and ethanol: yield ≥55%. 17 (L = P(OMe)3): 1H NMR (CD2Cl2, 20 °C) δ 7.52−6.86 (m, 35H, Ph), 4.89, 4.82 (d, 5H, Cp), 3.53, 3.50 (d, 9H, CH3 phos), ABCD3XY spin systs (ABCD = 1H, XY = 31P) (6H, CH3CHCH2), δA 3.47, δB 3.00, δC 2.67, δD 1.54, JAB = 12.7, JAC = 7.7, JAD = 5.8, JAX = 10.7, JAY = 0.1, JBC = 0.9, JBD = 0.6, JBX = 0.4, JBY = 0.1, JCD = 0.6, JCX = 13.5, JCY = 0.1, JDX = 1.0, JDY = 0.1 Hz, δA 3.60, δB 3.38, δC 2.49, δD 1.68, JAB = 10.8, JAC = 7.6, JAD = 5.4, JAX = 12.8, JAY = 0.1, JBC = 0.3, JBD = 0.4, JBX = 0.2, JBY = 0.1, JCD = 0.4, JCX = 13.2, JCY = 0.1, JDX = 1.2, JDY = 0.2, JXY = 64.0 Hz; 31P{1H} NMR (CD2Cl2, 20 °C) δ AB spin systs, δA 144.5, δB 48.4, JAB = 63.0 Hz, δA 144.6, δB 49.7, JAB = 63.9 Hz; 13C{1H} NMR (CD2Cl2, 20 °C) δ 165− 122 (m, Ph), 88.64, 88.03 (s, Cp), 61.60, 61.42 (s, CH), 54.5 (d, CH3 phos), 44.36 (s), 41.2 (d) (CH2), 24.54, 24.50 (s, CH3 propyl). Anal. Calcd for C53H55BO3P2Ru (913.83): C, 69.66; H, 6.07. Found: C, 69.82; H, 6.16. ΛM = 51.6 Ω−1 mol−1 cm2. 18 (L = P(OEt)3): 1H NMR (CD2Cl2, 20 °C) δ 7.52−6.88 (m, 35H, Ph), 4.88, 4.87 (s, 5H, Cp), 3.89, 3.82 (m, 6H, CH2 phos), ABCD3XY spin systs (ABCD = 1H, XY = 31P) (6H, CH3CHCH2), δA 3.46, δB 2.99, δC 2.70, δD 1.62, JAB = 12.5, JAC = 7.8, JAD = 6.1, JAX = 10.6, JAY = 0.1, JBC = 0.9, JBD = 0.6, JBX = −0.1, JBY = 0.1, JCD = 0.6, JCX = 14.0, JCY = JDX = JDY = 0.1 Hz, δA 3.60, δB 3.50, δC 2.52, δD 1.72, JAB = 12.4, JAC = 7.9, JAD = 5.9, JAX = 11.3, JAY = 0.1, JBC = 0.2, JBD = 0.1, JBX = −0.1, JBY = 0.1, JCD = 0.3, JCX = 13.3, JCY = 0.1, JDX = 1.3, JDY = 0.1 Hz, 1.26, 1.25, 1.20 (t, 9H, CH3 phos); 31P{1H} NMR (CD2Cl2, 20 °C) δ AB spin systs, δA 139.7, δB 49.8, JAB = 64.0 Hz, δA 139.3, δB 48.3, JAB = 63.0 Hz; 13C{1H} NMR (CD2Cl2, 20 °C) δ 165−122 (m, Ph), 88.91, 88.17 (s, Cp), 64.35, 64.13 (d, CH2 phos), 61.32, 61.23 (s, CH), 44.38, 44.35 (s, CH2), 24.55, 24.48 (s, CH3 propyl), 16.15, 15.07 (s, CH3 phos). Anal. Calcd for C56H61BO3P2Ru (955.91): C, 70.36; H, 6.43. Found: C, 70.12; H, 6.35. ΛM = 52.9 Ω−1 mol−1 cm2. [Ru(η5-C5H5){η1-NC(CN)CH2C(Ar1Ar2)N(H)}(PPh3)(L)]BPh4 (19, 20).

Mixed-ligand compounds were prepared exactly like the related bis(triphenylphosphine) complex 10: yield ≥85%. 11 (L = P(OMe)3): 1H NMR (CD2Cl2, 20 °C) δ 7.52−6.87 (m, 35H, Ph), 4.85 (s, 5H, Cp), 3.49 (d, 9H, CH3), ABCDXY spin syst (ABCD = 1 H, XY = 31P) (4H, CH2CH2), δA, δB 2.99, δC, δD 2.71, JAB = JCD = 12.1, JAC = JBD = 9.0, JAD = JBC = 0.3, JAX = JBX = 5.2, JAY = JBY = 0.2, JCX = JDX = 5.8, JCY = JDY = 0.2 Hz; 31P{1H} NMR (CD2Cl2, 20 °C) δ AB spin syst, δA 145.4, δB 49.6, JAB = 61.1 Hz; 13C{1H} NMR (CD2Cl2, 20 °C) δ 165−122 (m, Ph), 87.82 (s, Cp), 54.3 (d, CH3), 38.25 (d, CH2CH2). Anal. Calcd for C52H53BO3P2Ru (899.80): C, 69.41; H, 5.94. Found: C, 69.27; H, 6.05. ΛM = 53.6 Ω−1 mol−1 cm2. 12 (L = P(OEt)3): 1H NMR (CD2Cl2, 20 °C) δ 7.52−6.87 (m, 35H, Ph), 4.82 (s, 5H, Cp), 3.86 (m, 6H, CH2 phos), ABCDXY spin syst (ABCD = 1H, XY = 31P) (4H, CH2CH2), δA, δB 3.01, δC, δD 2.70, JAB = JCD = 12.7, JAC = JBD = 0.8, JAD = JBC = 8.5, JAX = JBX = 5.8, JAY = JBY = 0.2, JCX = JDX = 5.8, JCY = JDY = 0.2 Hz, 1.18 (t, 9H, CH3); 31P{1H} NMR (CD2Cl2, 20 °C) δ AB spin syst, δA 140.0, δB 49.7, JAB = 60.8 Hz; 13 C{1H} NMR (CD2Cl2, 20 °C) δ 165−122 (m, Ph), 88.14 (s, Cp), 63.95 (d, CH2 phos), 38.43 (dd, CH2CH2), 16.16 (d, CH3). Anal. Calcd for C55H59BO3P2Ru (941.88): C, 70.13; H, 6.31. Found: C, 70.27; H, 6.44. ΛM = 54.1 Ω−1 mol−1 cm2. 13 (L = PPh(OEt)2): 1H NMR (CD2Cl2, 20 °C) δ 7.55−6.86 (m, 40H, Ph), 4.67 (s, 5H, Cp), 3.85, 3.48 (m, 4H, CH2 phos), ABCDXY spin syst (ABCD = 1H, XY = 31P) (4H, CH2CH2), δA, δB 3.07, δC, δD 2.65, JAB = JCD = 12.9, JAC = JBD = 0.4, JAD = JBC = 8.5, JAX = JBX = 5.4, JAY = JBY = 0.2, JCX = JDX = 5.4, JCY = JDY = 0.2 Hz, 1.26, 1.16 (t, 6H, CH3); 31P{1H} NMR (CD2Cl2, 20 °C) δ AB spin syst, δA 164.85, δB 49.56, JAB = 52.6 Hz; 13C{1H} NMR (CD2Cl2, 20 °C) δ 165−122 (m, Ph), 88.87 (s, Cp), 66.74, 66.55 (d, CH2 phos), 40.8 (dd, CH2CH2), 16.62, 16.41 (d, CH3). Anal. Calcd for C59H59BO2P2Ru (973.93): C, 72.76; H, 6.11. Found: C, 72.61; H, 6.19. ΛM = 55.1 Ω−1 mol−1 cm2. 14 (L = ButNC): unstable oily product not fully characterized. Reaction of [Ru(η5-C5H5){η1-NNC(C12H8)CH2CH2}(PPh3){P(OMe)3}]BPh4 (6c) with P(OMe)3: Preparation of [Ru(η5-C5H5)(PPh3){P(OMe)3}2]BPh4 (15) and C12H8CCH2CH2 (16c). An excess of trimethyl phosphite (P(OMe)3; 0.3 mmol, 37 μL) was added to a solution of compound 6c (102 mg, 0.092 mmol) in 1,2-dichloroethane (12 mL), and the reaction mixture was refluxed for 4 h. The solvent was removed by evaporation under reduced pressure to give an oil, which was triturated with ethanol (1 mL). A yellow solid, characterized as complex 15, slowly separated out from the resulting solution on cooling to −25 °C, which was filtered and dried under vacuum. The mother liquor was chromatographed on a silica gel column (50 cm) using a mixture of petroleum ether (40−60 °C), dichloromethane, and ethanol, in 20:5:2 ratio, as eluent. The first eluted species was evaporated to dryness and characterized as compound 16c. 15: 1H NMR (CD2Cl2, 20 °C) δ 7.65−6.88 (m, 35H, Ph), 4.87 (s, 5H, Cp), 3.46 (d, 18H, CH3); 31P{1H} NMR (CD2Cl2, 20 °C) δ A2B spin syst, δA 197.53, δB 99.5, JAB = 51.1 Hz. Anal. Calcd for C53H58BO6P3Ru (995.83): C, 63.92; H, 5.87. Found: C, 64.05; H, 5.93. ΛM = 54.3 Ω−1 mol−1 cm2. 16c: 1H NMR (CD2Cl2, 20 °C) δ 7.85−7.07 (m, 8H, fluorene), 0.89 (s, 4H, CH2); MS M+ m/z 192. [Ru(η5-C5H5)(η2-CH3CHCH2)(PPh3)(L)]BPh4 (17, 18).

An excess of acrylonitrile (CH2CH(CN); 19 μL, 0.3 mmol) was added to a solution of the appropriate diazoalkane complex [Ru(η5C5H5)(N2CAr1Ar2)(PPh3)(L)]BPh4 (2, 3; 0.1 mmol) in CH2Cl2 (4 mL), and the reaction mixture was stirred for 8 h. The solvent was removed under reduced pressure to give an oil, which was triturated with ethanol (2 mL) containing an excess of NaBPh4 (0.2 mmol, 68 mg). A yellow solid slowly separated out, which was filtered and crystallized from CH2Cl2/EtOH: yield ≥70%. 19b (L = P(OMe)3, Ar1 = Ph, Ar2 = p-tolyl): IR (KBr, cm−1) νCN 2213 (w); 1H NMR (CD2Cl2, 20 °C) δ 7.51−6.61 (m, 44H, Ph), ABC spin syst (3H, H1−H4), δA 7.08, δB 3.61, δC 3.31, JAB = 10.3, JAC = 18.9, JBC = −17.5 Hz, 4.74, 4.72 (d, 5H, Cp), 3.39, 3.38 (d, 9H, CH3 phos), 2.37, 2.34 (s, 3H, CH3 p-tolyl); 31P{1H} NMR (CD2Cl2, 20 °C) δ AB, δA 144.09, δB 47.80, JAB = 69.1; δA 143.79, δB 47.88, JAB = 69.1 Hz; 13C{1H} NMR (CD2Cl2, 20 °C) δ 165−122 (m, Ph), 136.29 (br, C5), 114.10 (s, CN), 83.34 (s br, Cp), 76.29, 76.20 (s, C3), 54.11, 53.97 (d, CH3 phos), 47.95, 47.89 (s, C4), 21.14, 21.10 (s, CH3 p-tolyl). Anal. Calcd for 3573

dx.doi.org/10.1021/om500481d | Organometallics 2014, 33, 3570−3582

Organometallics

Article

C67H64BN3O3P2Ru (1133.07): C, 71.02; H, 5.69; N, 3.71. Found: C, 71.18; H, 5.61; N, 3.64. ΛM = 55.0 Ω−1 mol−1 cm2. 19c (L = P(OMe)3, Ar1Ar2 = C12H8): IR (KBr, cm−1) νCN 2207 (w); 1 H NMR (CD2Cl2, 20 °C) δ 8.00−6.17 (m, 43H, Ph), 4.99 (s, 5H, Cp), ABC spin syst (3H, H1−H4), δA 7.09, δB 3.45, δC 3.34, JAB = 10.3, JAC = 18.9, JBC = −17.5 Hz, 3.32 (d, 9H, CH3); 31P{1H} NMR (CD2Cl2, 20 °C) δ AB, δA 146.87, δB 44.97, JAB = 69.2 Hz; 13C{1H} NMR (CD2Cl2, 20 °C) δ 165−119 (m, Ph), 133.46 (br, C5), 114.28 (s, CN), 83.77 (s, Cp), 74.61 (s, C3), 53.68 (d, CH3), 46.21 (s, C4). Anal. Calcd for C66H60BN3O3P2Ru (1117.03): C, 70.97; H, 5.41; N, 3.76. Found: C, 71.16; H, 5.37; N, 3.69. ΛM = 53.3 Ω−1 mol−1 cm2. 20b (L = P(OEt)3, Ar1 = Ph, Ar2 = p-tolyl): IR (KBr, cm−1) νCN 2213 (w); 1H NMR (CD2Cl2, 20 °C) δ 7.50−6.85 (m, 44H, Ph), ABC spin syst (3H, H1−H4), δA 3.31, δB 3.51, δC 7.29 JAB = 10.0, JAC = 20.5, JBC = −17.9 Hz, 4.70, 4.69 (s, 5H, Cp), 3.92, 3.61 (m, 6H, CH2 phos), 2.38, 2.34 (s, 3H, CH3 p-tolyl), 1.13, 1.12 (s, 9H, CH3 phos); 31P{1H} NMR (CD2Cl2, 20 °C) δ AB, δA 138.51, δB 48.07, JAB = 69.10; δA 138.22, δB 48.12, JAB = 69.10 Hz; 13C{1H} NMR (CD2Cl2, 20 °C) δ 165−121 (m, Ph), 136.08, 135.90 (br, C5), 114.22, 114.18 (s, CN), 83.37, 83.22 (s, Cp), 76.26, 76.15 (br, C3), 63.64, 62.31 (d, CH2 phos), 48.18, 48.11 (s, C4), 21.10, 21.06 (s, CH3 p-tolyl), 16.18, 16.10 (d, CH3 phos). Anal. Calcd for C70H70BN3O3P2Ru (1175.15): C, 71.54; H, 6.00; N, 3.58. Found: C, 71.36; H, 5.95; N, 3.67. ΛM = 52.4 Ω−1 mol−1 cm2. [Ru(η5-C5H5){η2-CHCHC(O)OC(O)}(PPh3){P(OMe)3}]BPh4 (21) and [Ru(η 5 -C 5 H 5 ){η 2 -CH 3 OCOC(H)C(H)COOCH 3 }(PPh 3 ){P(OMe)3}]BPh4 (22). In a 25 mL three-necked round-bottomed flask were placed 0.100 g (0,093 mmol) of the diazoalkane complex [Ru(η5-C5H5){N2C(Ph)(p-tolyl)}(PPh3){P(OMe)3}]BPh4 (2b), an excess (0.3 mmol) of either maleic anhydride (ma; 29 mg) or dimethyl maleate (dmm; 43 mg), and 5 mL of CH2Cl2. The reaction mixture was stirred for 24 h and then the solvent removed under reduced pressure to give an oil, which was triturated with ethanol (2 mL). A yellow solid slowly separated out, which was filtered and crystallized from CH2Cl2/EtOH: yield ≥75%. 21: IR (KBr, cm−1) νCO 1826, 1763 (s); 1H NMR (CD2Cl2, 20 °C) δ 7.65−6.87 (m, 35H, Ph), 5.01 (s, 5H, Cp), ABXY spin syst (X, Y = 1H) (2H, CH), δX 4.23, δY 4.02, JAX = 15.5, JAY = 13.45, JBX = 0.40, JBY = 0.65, JXY = 4.27 Hz, 3.58 (d, 9H, CH3); 31P{1H} NMR (CD2Cl2, 20 °C) δ AB spin syst, δA 133.1, δB 41.98, JAB = 55.0 Hz; 13C{1H} NMR (CD2Cl2, 20 °C) δ 172.76, 171.69 (s, CO), 165−122 (m, Ph), 94.8 (s, Cp), 56.25 (d, CH3), 46.05, 43.14 (d, CH). Anal. Calcd for C54H51BO6P2Ru (969.81): C, 66.88; H, 5.30. Found: C, 66.76; H, 5.38. ΛM = 52.6 Ω−1 mol−1 cm2. 22: IR (KBr, cm−1) νCO 1746, 1722 (s); 1H NMR (CD2Cl2, 20 °C) δ 7.58−6.87 (m, 35H, Ph), 5.12 (s, 5H, Cp), 3.77, 3.72 (s, 6H, CH3COO), ABXY spin syst (X, Y = 1H) (2H, CH), δX 3.62, δY 3.32, JAX = 16.6, JAY = 12.6, JBX = 0.8, JBY = 0.45, JXY = 9.45 Hz, 3.51 (d, 9H, CH3 phos); 31 1 P{ H} NMR (CD2Cl2, 20 °C) δ AB spin syst, δA 138.4, δB 42.70, JAB = 58.9 Hz; 13C{1H} NMR (CD2Cl2, 20 °C) δ 173.21, 170.61 (s, CO), 165−122 (m, Ph), 92.15 (s, Cp), 55.87 (d, CH3 phos), 54.08, 46.74 (s, CH), 53.32, 52.62 (s, CH3COO). Anal. Calcd for C56H57BO7P2Ru (1015.88): C, 66.21; H, 5.66. Found: C, 66.03; H, 5.70. ΛM = 53.5 Ω−1 mol−1 cm2. Reaction of [Ru(η5-C5H5){η1-NC(CN)CH2C(Ph)(p-tolyl)N(H)}(PPh3){P(OMe)3}]BPh4 (19b) with P(OMe)3: Separation of N C(CN)CH2C(Ph)(p-tolyl)NH (23b). The reaction was carried out exactly as for the related 4,5-dihydro-3H-pyrazole 6c, but at room temperature for 48 h. The solid which separated out was [Ru(η5-C5H5) (PPh3){P(OMe)3}2]BPh4 (15), whereas that obtained by chromatography of the mother liquor was the free 1H-pyrazoline compound 23b: IR (KBr, cm−1) νNH 3268 (m), νCN 2213 (w); 1H NMR (CD2Cl2, 20 °C) δ 7.65−6.70 (m, 9H, Ph), AB spin syst (2H, H4), δA 3.74, δB 3.46, JAB = −11.7 Hz, 2.33 (s, 3H, CH3). [Ru(η 5-C 5H5){η 1-NNC(Ar1Ar2)CHCH}(PPh 3 ){P(OMe) 3}]BPh4 (24). A solution of the appropriate diazoalkane complex [Ru(η5C5H5)(N2CAr1Ar2)(PPh3){P(OMe)3}]BPh4 (2; 0.11 mmol) in dichloromethane (10 mL) was stirred under acetlylene (HCCH; 1 atm) for 24 h. The solvent was removed under reduced pressure to

give an oil, which was triturated with ethanol (3 mL) containing an excess of NaBPh4 (0.15 mmol, 51 mg). A yellow solid slowly separated out, which was filtered and crystallized from CH2Cl2/EtOH: yield ≥80%. 24b (Ar1 = Ph, Ar2 = p-tolyl): 1H NMR (CD2Cl2, 20 °C) δ 7.49− 6.86 (m, 44H, Ph), 7.36 (m, 1H, H4), 7.24 (m, 1H, H5), 4.76 (dd, 5H, Cp, 3J1H31P = 1.8, 3J1H31P = 0.5 Hz), 3.32 (d, 9H, CH3 phos), 2.31, 2.30 (s, 3H, CH3 p-tolyl); 31P{1H} NMR (CD2Cl2, 20 °C) δ AB spin systs, δA 145.59, δB 47.90, JAB = 68.96, δA 145.55, δB 47.88, JAB = 68.94 Hz; 13 C{1H} NMR (CD2Cl2, 20 °C) δ 165−122 (m, Ph), 152.71 (s, C5), 145.55 (s, C4), 104.09 (s, C3), 84.96 (s br, Cp), 53.08 (dd, CH3 phos), 21.12 (s, CH3 p-tolyl). Anal. Calcd for C66H63BN2O3P2Ru (1106.05): C, 71.67; H, 5.74; N, 2.53. Found: C, 71.59; H, 5.68; N, 2.49. ΛM = 53.7 Ω−1 mol−1 cm2. 24c (Ar1Ar2 = C12H8): 1H NMR (CD2Cl2, 20 °C) δ 8.71−6.86 (m, 43H, Ph), 7.62 (d, 1H, H4), 6.82 (d, 1H, H5, 3J1H1H = 3.0 Hz), 4.81 (s, 5H, Cp), 3.48 (d, 9H, CH3); 31P{1H} NMR (CD2Cl2, 20 °C) δ AB spin syst, δA 143.6, δB 47.5, JAB = 68.2 Hz; 13C{1H} NMR (CD2Cl2, 20 °C) δ 165−119 (m, Ph), 155.24 (s, C5), 141.16 (s, C4), 105.18 (s, C3), 85.21 (t, Cp, 2J13C31P = 2.1 Hz), 53.3 (d, CH3). Anal. Calcd for C65H59BN2O3P2Ru (1090.00): C, 71.62; H, 5.46; N, 2.57. Found: C, 71.73; H, 5.53; N, 2.50. ΛM = 51.1 Ω−1 mol−1 cm2. [Ru(η5-C5H5){CC(H)R}(PPh3){P(OMe)3}]BPh4 (25, 26). An excess of the appropriate alkyne HCCR (0.14 mmol) was added to a solution of the diazoalkane complex [Ru(η5-C5H5){N2C(Ph)(p-tolyl)}(PPh3){P(OMe)3}]BPh4 (2b; 0.10 g, 0.093 mmol) in 1,2-dichloroethane (10 mL), and the reaction mixture was refluxed for 30 min. The solvent was removed under reduced pressure to give an oil, which was triturated with ethanol (2 mL) containing an excess of NaBPh4 (0.15 mmol, 51 mg). A pink solid slowly separated out, which was filtered and crystallized from CH2Cl2/EtOH: yield ≥60%. 25 (R = Ph): IR (KBr, cm−1) νRuCC 1653 (m); 1H NMR (CD2Cl2, 20 °C) δ 7.51−6.87 (m, 40H, Ph), 5.57 (m, 1H, CH), 5.36 (s, 5H, Cp), 3.39 (d, 9H, CH3); 31P{1H} NMR (CD2Cl2, 20 °C) δ AB spin syst, δA 138.1, δB 47.4, JAB = 48.5 Hz; 13C{1H} NMR (CD2Cl2, 20 °C) δ 359.28 (dd, Cα, 2J13C31P = 21.9, 2J13C31P = 14.3 Hz), 165−122 (m, Ph), 118.34 (s, Cβ), 93.25 (s, Cp), 54.48 (d, CH3). Anal. Calcd for C58H55BO3P2Ru (973.88): C, 71.53; H, 5.69. Found: C, 71.66; H, 5.61. ΛM = 54.0 Ω−1 mol−1 cm2. 26 (R = But): IR (KBr, cm−1) νRuCC 1675, 1644 (m); 1H NMR (CD2Cl2, 20 °C) δ 7.55−6.87 (m, 35H, Ph), 5.22 (d, 5H, Cp), 4.31 (dd, 1H, CH), 3.99 (d, 9H, CH3 phos), 1.10 (s, 9H, CH3 But); 31P{1H} NMR (CD2Cl2, 20 °C) δ AB spin syst, δA 140.38, δB 47.73, JAB = 50.7 Hz; 13C{1H} NMR (CD2Cl2, 20 °C) δ 353.07 (dd, Cα, 2J13C31P = 20.2, 2J13C31P = 15.3 Hz), 165−122 (m, Ph), 124.86 (s, Cβ), 92.33 (s, Cp), 54.03 (d, CH3 phos), 32.53 (s, C But), 32.14 (s, CH3 But). Anal. Calcd for C56H59BO3P2Ru (953.89): C, 70.51; H, 6.23. Found: C, 70.65; H, 6.11. ΛM = 52.8 Ω−1 mol−1 cm2. [Ru(η5-C5H5){η1-NNC(Ar1Ar2)C(H)C(COOMe)}(PPh3){P(OMe)3}]BPh4 (27) and [Ru(η5-C5H5){η1-NNC(Ar1Ar2)C(H)C(COOEt)}(PPh3){P(OMe)3}]BPh4 (28). An excess of the alkyl propiolate HCCCOOR (R = Me, Et; 0.30 mmol) was added to a solution of the appropriate diazoalkane complex [Ru(η5-C5H5)(N2CAr1Ar2)(PPh3){P(OMe)3}]BPh4 (2; 0.1 mmol) in dichloromethane (5 mL), and the reaction mixture was stirred for 48 h. The solvent was removed under reduced pressure to give an oil, which was triturated with ethanol (3 mL) containing an excess of NaBPh4 (0.15 mmol, 51 mg). A reddish brown solid slowly separated out, which was filtered and crystallized from CH2Cl2/EtOH: yield ≥55%. 27b (Ar1 = Ph, Ar2 = p-tolyl): IR (KBr, cm−1) νCO 1729 (s); 1H NMR (CD2Cl2, 20 °C) δ 7.62 (d, 1H, CH, H4, 5J1H31P = 5.0 Hz), 7.57−6.63 (m, 44H, Ph), 4.81 (d, 5H, Cp, 3J1H31P = 2.6 Hz), 3.73 (s, 3H, CH3COO), 3.37 (d, 9H, CH3 phos), 2.34 (s, 3H, CH3 p-tolyl); 31P{1H} NMR (CD2Cl2, 20 °C) δ AB spin syst, δA 145.15, δB 47.10, JAB = 68.0 Hz; 13 C{1H} NMR (CD2Cl2, 20 °C) δ 165−122 (m, Ph), 159.98 (s, CO), 155.95 (s, C4), 147.04 (s, C5), 103.93 (br, C3), 84.77 (s, Cp), 52.59 (d, CH3 phos), 52.43 (s, CH3COO), 20.46 (s, CH3 p-tolyl). Anal. Calcd for C68H65BN2O5P2Ru (1164.08): C, 70.16; H, 5.63; N, 2.41. Found: C, 70.29; H, 5.71; N, 2.30. ΛM = 51.4 Ω−1 mol−1 cm2. 3574

dx.doi.org/10.1021/om500481d | Organometallics 2014, 33, 3570−3582

Organometallics

Article

Scheme 1. a

28b (Ar1 = Ph, Ar2 = p-tolyl): IR (KBr, cm−1) νCO 1721 (s); 1H NMR (CD2Cl2, 20 °C) δ 7.62 (s br, 1H, CH, H4), 7.57−6.64 (m, 44H, Ph), 4.83 (d, 5H, Cp,3J1H31P = 3.2 Hz), 4.17, 4.16 (q, 2H, CH2), 3.39 (d, 9H, CH3 phos), 2.37 (s, 3H, CH3 p-tolyl), 1.20 (t, 3H, CH3 Et); 31P{1H} NMR (CD2Cl2, 20 °C) δ AB spin syst, δA 145.32, δB 47.10, JAB = 68.0 Hz; 13C{1H} NMR (CD2Cl2, 20 °C) δ 165−122 (m, Ph), 159.24 (s, CO), 156,57 (s, C4), 148.4 (br, C5), 104.51 (br, C3), 85.62 (d, Cp), 62.69 (s, CH2), 53.32 (d, CH3 phos), 21.29 (s, CH3 p-tolyl), 14.11 (s, CH3 Et). Anal. Calcd for C69H67BN2O5P2Ru (1178.11): C, 70.34; H, 5.73; N, 2.38. Found: C, 70.26; H, 5.64; N, 2.31. ΛM = 51.6 Ω−1 mol−1 cm2. 28c (Ar1Ar2 = C12H8): IR (KBr, cm−1) νCO 1715 (s); 1H NMR (CD2Cl2, 20 °C) δ 7.65 (s br, 1H, CH, H4), 8.60−6.24 (m, 43H, Ph), 4.86 (s, 5H, Cp), 4.53 (q, 2H, CH2), 3.49 (d, 9H, CH3 phos), 1.20 (t, 3H, CH3 Et); 31P{1H} NMR (CD2Cl2, 20 °C) δ AB spin syst, δA 145.43, δB 47.20, JAB = 68.0 Hz. Anal. Calcd for C68H63BN2O5P2Ru (1162.07): C, 70.28; H, 5.46; N, 2.41. Found: C, 70.40; H, 5.57; N, 2.34. ΛM = 52.4 Ω−1 mol−1 cm2. X-ray Data Collection and Refinement. Crystallographic data for complexes 21 and 24c were collected on a Bruker Smart 1000 CCD diffractometer at CACTI (Universidade de Vigo) using graphitemonochromated Mo Kα radiation (λ = 0.71073 Å), and were corrected for Lorentz and polarization effects. The software SMART16 was used for collecting frames of data and indexing reflections, and the determination of lattice parameters. Crystallographic data for 19b were collected at room temperature using a Bruker Smart 6000 CCD detector and Cu Kα radiation (λ = 1.54178 Å) generated by a Incoatec microfocus source equipped with Incoatec Quazar MX optics. The software APEX217 was used for collecting frames of data and indexing reflections and the determination of lattice parameters. In all cases, the software SAINT18 was used for integration of the intensity of reflections and SADABS19 for scaling and empirical absorption correction. The crystallographic treatment was performed with the Oscail program.20 The structures of 19b and 21 were solved by the Patterson method21 and that of 24c by using SUPERFLIP.22 Both structures were refined by fullmatrix least squares based on F2.21 Non-hydrogen atoms were refined with anisotropic displacement parameters. Hydrogen atoms were included in idealized positions and refined with isotropic displacement parameters, except those of the maleic anhydride ligand. These were found in the final density map and refined isotropically. Details of crystal data and structural refinement are given in the Supporting Information (Table S1).

a

Definitions: L = PPh3 (1), P(OMe)3 (2), P(OEt)3 (3), PPh(OEt)2 (4), ButNC (5); Ar1 = Ar2 = Ph (a), Ar1 = Ph, Ar2 = p-tolyl (b), Ar1Ar2 = C12H8 (c), Ar1 = Ph, Ar2 = PhCO (d).

similar to that found in the solid state for 3b. In the spectra of isocyanide derivatives [Ru(η5-C5H5)(N2CAr1Ar2)(PPh3)(ButNC)]BPh4 (5), a strong band at 2140−2130 cm−1 also appears, due to νCN of the isocyanide. Reactions with Ethylene. The reactions of diazoalkane complexes [Ru(η5-C5H5)(N2CAr1Ar2)(PPh3)(L)]BPh4 (1−5) with ethylene are shown in Scheme 2. Although triphenylphosphine complexes [Ru(η5-C5H5)(N2CAr1Ar2)(PPh3)2]BPh4 (1) react with CH2CH2 (1 atm) to give quantitatively the ethylene complex [Ru(η5-C5H5)(η2CH2CH2)(PPh3)2]BPh4 (10), the mixed-ligand diazoalkane derivatives [Ru(η5-C5H5)(N2CAr1Ar2)(PPh3)(L)]BPh4 (2−5) react with ethylene, under mild conditions (1 atm, room temperature), to give not only small amounts of ethylene complexes [Ru(η5-C5H5)(η2-CH2CH2)(PPh3)(L)]BPh4 (11−14) but also the novel derivatives [Ru(η5-C5H5){η1-NNC(Ar1Ar2)CH2CH2}(PPh3)(L)]BPh4 (6−9), which contain 4,5-dihydro3H-pyrazole as a ligand. The reaction proceeds with (3 + 2) cycloaddition of the ethylene to the coordinate diazoalkane giving 4,5-dihydro-3Hpyrazole derivatives 6−9, in which the novel heterocycle acts as a ligand. Parallel substitution of the diazoalkane by CH2CH2 also proceeds to a small extent, yielding ethylene complexes 11−14. The two complexes formed by the reaction, [Ru-

■

RESULTS AND DISCUSSION Preparation of Diazoalkane Complexes. Half-sandwich diazoalkane complexes of the type [Ru(η5-C5H5)(N2CAr1Ar2)(PPh3)(L)]BPh4 (1−5) were prepared by reacting the chloro compounds RuCl(η5-C5H5)(PPh3)(L) with an excess of diazoalkane in ethanol, in the presence of NaBPh4, as shown in Scheme 1. The reaction proceeded with substitution of the chloride with the Ar1Ar2CN2 group, affording the final diazoalkane complexes 1−5. Crucial for successful synthesis was the presence of the NaBPh4 salt which, favoring substitution of the Cl− ligand, allowed the complexes to separate as orange solids. Both bis(triphenylphosphine) [Ru(η5-C5H5)(PPh3)2]+ and mixed-ligand [Ru(η5-C5H5)(PPh3)(L)]+ fragments (L = phosphites, tert-butyl isocyanide) are able to stabilize diazoalkane complexes 1−5, which were isolated as solids stable in air and in solution of polar organic solvents, where they behave as 1:1 electrolytes.23 Analytical and spectroscopic data (IR and NMR) confirm the proposed formulation, which was further supported by an X-ray crystal structure determination10 of [Ru(η5-C5H5){N2C(Ph)(p-tolyl)}(PPh3){P(OEt)3}]BPh4 (3b). The IR spectra show a medium-intensity band at 1967− 1900 cm−1, attributed to νCNN of the coordinated diazoalkane. Comparison of this value with literature data also suggests the end-on η1 coordination mode for the Ar1Ar2CN2 group,

(η 5-C 5H 5)-{η 1-NNC(Ar1Ar2)CH 2CH 2}(PPh 3 )(L)]BPh 4 (6−9) and [Ru(η 5-C5H5)(η 2-CH 2CH 2)(PPh3)(L)]BPh4 (11−14), were recovered as solids and separated by fractional crystallization in good yields (70−80% for 6−9, 8−10% for 11−13, traces for 14) as yellow-orange crystalline solids. In the mother liquor, free diazoalkane Ar1Ar2CN2 forming as a result of the substitution with CH2CH2 was also detected, indicating that only the coordinated diazoalkane undergoes cyclization with ethylene to yield 4,5-dihydro-3Hpyrazole species. The reaction of free diazoalkane24 with ethylene is very rare25 and needs quite drastic conditions to proceed (11 days, 55 °C). Coordination with the Ru(η 5-C5H5)(PPh3)(L) fragment activates Ar1Ar2CN2 species toward cyclization, allowing the formation of 3H-pyrazole species under very mild conditions. However, only mixed-ligand fragments containing phosphite or isocyanide can activate diazoalkanes toward cyclization with CH2CH2, since the bis(triphenylphosphine) complexes [Ru(η5-C5H5)(N2CAr1Ar2)(PPh3)2]BPh4 (1) give exclusively substitution reaction with ethylene, affording η2-CH2CH2 derivatives 10. Activation of diazoalkane by coordination was also observed in imine aziridination catalyzed by ruthenium complexes,8m but in that case a carbene transfer reaction to imine occurs. 3575

dx.doi.org/10.1021/om500481d | Organometallics 2014, 33, 3570−3582

Organometallics

Article

Scheme 2. a

a

Definitions: L = P(OMe)3 (6, 11), P(OEt)3 (7, 12), PPh(OEt)2 (8, 13), ButNC (9, 14); Ar1 = Ar2 = Ph (a), Ar1 = Ph, Ar2 = p-tolyl (b), Ar1Ar2 = C12H8 (c).

The 4,5-dihydro-3H-pyrazole ligand is very stable to substi5

determination10 of [Ru(η5-C5H5){η1-NNC(C12H8)CH2CH2}(PPh3){P(OMe)3}]BPh4 (6c). The 4,5-dihydro-3H-pyrazole complexes [Ru(η5-C5H5){η1-

1

tution in the complexes [Ru(η -C5H5){η -NNC(Ar1Ar2)CH2CH2}(PPh3)(L)]BPh4 (6−9) and, at room temperature, cannot be removed by treatment with excesses of Cl−, phosphine, carbonyl, or other ligands. Instead, in refluxing dichloroethane,

NNC(Ph)(p-tolyl)CH2CH2}(PPh3){P(OMe)3}]BPh4 (6b− 9b), containing two different substituents at the C3 carbon atom of the heterocycle, were obtained as a mixture of two diastereoisomers, owing to the presence of two chiral centers in the molecule: i.e., the ruthenium atom and the C3 atom of the heterocyclic ligand. 1H, 3P, and 13C NMR spectra confirm the presence of the two diastereoisomers, showing two sets of signals for the nuclei of the ligands. In particular, the 31P NMR spectra of 6b−8b show two AB quartets, whereas the proton spectra show two singlets for the η5-C5H5 protons and two for the CH3 groups of the p-tolyl substituent at C3 of the 4,5-dihydro-3H-pyrazole. In addition, two groups of partially overlapping signals were observed for the H4 and H5 protons of the ligand, fitting the proposed formulation for the complexes. The spectrum of the isocyanide derivative [Ru(η5-C5H5)-

[Ru(η 5 -C 5 H 5 ){η 1 -NNC(C 1 2 H 8 )CH 2 CH 2 }(PPh 3 ){P(OMe)3}]BPh4 (6c) does react with an excess of P(OMe)3 with substitution of the 4,5-dihydro-3H-pyrazole ligand and formation of the phosphine complex [Ru(η5-C5H5)(PPh3){P(OMe)3}2]BPh4 (15) (Scheme 3), which was separated and characterized. Scheme 3. Substitution Reaction

{η1-NNC(Ph)(p-tolyl)CH2CH2}(PPh3)(ButNC)]BPh4 (9b) also shows two sets of signals, partially overlapping, for both the 3 P and 1H nuclei, supporting the presence of two diastereoisomers. The IR spectrum also shows a strong band at 2123 cm−1, due to νCN of ButNC, whereas in the 1H NMR spectrum the signal of the tert-butyl substituents appears as a singlet at 1.29 ppm, fitting the proposed formulation for 9b. The 31P NMR spectra of the related complexes [Ru(η5-

Unfortunately, the expected 4,5-dihydro-3H-pyrazole species

C5H5){η1-NNC(C12H8)CH2CH2}(PPh3)(L)]BPh4 (6c−8c)

NNC(C12H8)CH2CH2 could not be obtained by chromatographic separation from the reaction mixture, but only its probable decomposition product 16c. The formation of such a bicyclic compound is not surprising, owing to the known thermal26,27 or photochemical28 decomposition of pyrazolines to give cyclopropane. The refluxing conditions used to remove 4,5-dihydro3H-pyrazole caused decomposition of the azo species. Good analytical data were obtained for both 4,5-dihydro-3Hpyrazole (6−9) and η2-alkene derivatives (10−14), which were all isolated as yellow or orange solids, stable in air and in solution of polar organic solvents, where they behave as 1:1 electrolytes.23 Infrared and NMR spectra support the proposed formulations, which were further confirmed by an X-ray crystal structure

and [Ru(η5-C5H5){η1-NNC(Ph2)CH2CH2}(PPh3)(L)]BPh4 (6a), which contain only one chiral center, show only one AB quartet, and the 1H and 13C spectra support the presence of the heterocyclic ligand. In particular, a triplet at 2.32−2.20 ppm attributed to methylene protons H4 and two triplets at 4.90− 4.45 ppm attributed to methylene hydrogen atoms H5 were observed in the 1H NMR spectra. The 13C spectrum of 6c shows two singlets at 88.95 and 30.59 ppm which, in an HMQC experiment, were correlated with the multiplet at 4.84 ppm and the triplet at 2.23 ppm, respectively, and attributed to the C5 and C4 carbon atoms of the 4,5-dihydro-3H-pyrazole ligand. The singlet at 98.32 ppm was attributed to C3. 3576

dx.doi.org/10.1021/om500481d | Organometallics 2014, 33, 3570−3582

Organometallics

Article

4,5-dihydro-3H-pyrazole species. Cyclization with propylene is probably very slow and requires more drastic conditions, if it is to proceed. Styrene is also unreactive toward cyclization with coordinated diazoalkane, and this result may be attributed to either electronic or steric factors of the substituent CH3 or C6H5 of the alkene. However, although the steric requirements of the alkene may be important in determining the 1,3-dipolar cycloaddition of coordinate diazoalkanes, acrylonitrile (CH2C(H)CN) quickly reacts with [Ru(η5-C5H5)(N2CAr1Ar2)(PPh3)(L)]BPh4 (2, 3) to give exclusively the 1H-pyrazoline derivatives [Ru(η5-C5H5)

At room temperature, the proton spectra of ethylene complexes [Ru(η5-C5H5)(η2-CH2CH2)(PPh3)(L)]BPh4 (11−13) show two multiplets at 3.07−2.99 and 2.65−2.71 ppm, but only one triplet at 2.97 ppm appears for [Ru(η5-C5H5)(η2-CH2 CH2)(PPh3)2]BPh4 (10); they were attributed to the protons of the coordinated ethylene. Lowering the sample temperature caused some variations in the spectra, but ethylene peaks were still broadened even at −90 °C, suggesting that rotation of CH2CH2 still occurred at this temperature. However, the room-temperature pattern of mixed-ligand complexes 11−13 can be simulated by an ABCDXY model (X, Y = 31P) with the parameters reported in the Experimental Section, and the good fit between calculated and experimental spectra strongly supports the proposed attributions. In the 13C spectra, CH2CH2 carbon resonances appear as doublets at 38.25−40.80 ppm for 11−13 and as a singlet at 43.59 ppm for 10, whereas the 31P spectra are AB quartets for 11−13 and one singlet at 41.70 ppm for 10, fitting the proposed formulation for complexes 10−13. Reactions with Substituted Alkenes. The results obtained with ethylene prompted us to extend our study to the reactivity of coordinate diazoalkanes toward some electron-rich and electronpoor alkenes. The results are shown in Scheme 4.

{η1-NC(CN)CH2C(Ar1Ar2)NH}(PPh3)(L)]BPh4 (19, 20) in high yields. The reaction proceeds with (3 + 2) cycloaddition of CH2C(H)CN to the coordinated diazoalkane, giving 3H-pyrazole derivatives [Ru]− η1-NNC(Ar1Ar2)CH2CH(CN) (A) (Scheme 5), which tautomerize to the final 1H-pyrazoline derivatives 19 and 20. Scheme 5. a

Scheme 4. a

a

Definition: [Ru] = [Ru(η5-C5H5)(PPh3)(L)]+.

Tautomerization of the azacycle involves a 1,3-H shift from C to N and is probably favored by the CN group, making the CH(CN) hydrogen atom acidic. The presence of an electron-withdrawing group such as CN favors cyclization of the alkene rather than substitution, unlike the case for propylene which, containing the electron-donor group CH3, exclusively gives η2-CH3CHCH2 derivatives. In the monosubstituted alkenes CH2CHR, electronic factors seem to be more important than steric factors in leading the reaction of coordinated diazoalkane toward cyclization, affording 1H-pyrazoline derivatives. Surprisingly, the reactions of other activated alkenes, such as maleic anhydride (CHCHCO(O)CO, ma) and dimethyl maleate (CH3OCOC(H)C(H)COOCH3, dmm), proceed with substitution of the coordinated diazoalkane to give almost quantitatively the η2-alkene complexes [Ru(η5-C5H5){η2-RC(H)C(H)R}(PPh3)(L)]BPh4 (21, 22), which were isolated and characterized. No evidence of the formation of 3H-pyrazole complexes was obtained from NMR spectra, suggesting that, in these alkenes, despite the presence of two electron-withdrawing groups, steric hindrance of substituents prevents the cyclization reaction, affording only η2-alkene derivatives 21 and 22. Fumaronitrile ((NC)CHCH(CN)) was also reacted with diazoalkane complexes, but in this case the reaction was very slow, affording only a mixture of products after 2 days. Although the NMR spectra suggest the formation of a small amount of the 4,5-dihydro-3H-pyrazole complex, the main species is the starting diazoalkane complex, which reacts very slowly with the activated alkene, owing to the presence of two trans CN groups. Although the number of alkenes used was limited and no kinetic study was carried out, the results indicate that alkenes with little steric hindrance (CH2CH2) and/or containing

a Definitions: L = P(OMe)3 (17, 19, 21, 22), P(OEt)3 (18, 20); Ar1 = Ph, Ar2 = p-tolyl (b), Ar1Ar2 = C12H8 (c); ma = maleic anhydride, dmm = dimethyl maleate.

Under mild conditions (1 atm, room temperature), propylene (CH3C(H)CH2) does not react with diazolkane complexes 1−5. Instead, under pressure (7 atm, room temperature), substitution of the diazoalkane was observed, with formation of the propylene complex [Ru(η5-C5H5)(η2-CH3CHCH2)(PPh3)(L)]BPh4 (17, 18), but no evidence of a cycloaddition reaction was detected. In fact, in addition to η2-propylene complexes, some other unidentified products did form in the reaction under pressure, but NMR spectra excluded the formation of 3577

dx.doi.org/10.1021/om500481d | Organometallics 2014, 33, 3570−3582

Organometallics

Article

electron-withdrawing groups (CH2CH(CN)) do react with diazoalkane complexes to give (3 + 2) cycloaddition, whereas alkenes with either electron-donor groups (CH3CHCH2) or bulkier substituents only gave substitution of the diazoalkane, affording η2-alkene derivatives. Previous studies on the coordinated diazoalkane have shown that they can give both dinitrogen [M]−N2 and carbene [M]− CAr1Ar2 complexes.8f N−N bond cleavage has also been observed,8k as well as reduction of the coordinated N2CAr1Ar2 ligand.8i However, an example of the cycloaddition reaction has been reported for a C-bonded diazoalkane in Rh[η1-C(N2)SiMe3][P(OEt)3]3, affording the triazole derivative Rh[CC(SiMe3)N2NBut](ButNC)[P(OEt)3] in the reaction with ButNC.29 Ethene has also been previously reported7j to react with the diazoalkane complex RhCl(N2CC12H8)(PPri3)2, giving RhCl(η2-CH2CH2)(PPri3)2 and the fulvalene derivative CH3CHC(C12H8). Using the half-sandwich mixed-ligand fragment [Ru(η5C5H5)(PPh3)(L)]+ not only allowed coordination of the diazoalkane but also led to the unprecedented dipolar (3 + 2) cycloaddition of coordinate N2CAr1Ar2 to ethene and acrylonitrile, affording novel dihydro-3H-pyrazole molecules in one case and 3-cyano-1H-pyrazoline in the other.

Figure 1. ORTEP drawing of the cation of 19b at the 20% probability level. P(1) represents a PPh3 ligand and P(2) a P(OMe)3 ligand. Only the hydrogen atoms of the pyrazoline ligand are shown. Selected bond lengths (Å) are as follows: Ru−CT1, 1.87679(17); Ru−N(1), 2.1151(18); Ru−P(1), 2.3437(5); Ru−P(2), 2.2356(6). Cp ring: Ru− C(1), 2.228(2); Ru−C(2), 2.259(2); Ru−C(3), 2.238(2); Ru−C(4), 2.198(2); Ru−C(5), 2.199(2); C3N2 ring: N(1)−N(2), 1.379(3); N(1)−C(5), 1.309(3); N(2)−C(3) 1.502(3); C(4)−C(5), 1.488(4); C(3)−C(4), 1.556(3); C(6)−N(11), 1.137(3). Selected bond angles (deg): P(1)−Ru−P(2), 94.48(2); CT1−Ru−P(1), 120.917(15); CT1−Ru−P(2), 120.888(17); CT1−Ru−N(1), 127.66(5); N(1)− Ru−P(1), 92.12(5); N(1)−Ru−P(2), 92.21(5). CT1 represents the centroid of the Cp ligand.

The pyrazoline ligand η1-NC(CN)CH2C(Ar1Ar2)NH is relatively labile in complexes 19 and 20 and can be substituted at room temperature by P(OMe)3, yielding [Ru(η5-C5H5)(PPh3){P(OMe)3}2]BPh4 (15) and the free azacycle 23, which can be separated by chromatography (Scheme 6). Scheme 6. Substitution Reaction

The asymmetric units of 19b and 21 contain a BPh4− anion (not shown in the figures) and a ruthenium cation complex. In both cases, the cation complex contains a ruthenium atom in a half-sandwich piano-stool structure, coordinated by a Cp group, two phosphane ligands (one PPh3 and one P(OMe)3), and another ligand completing the octahedral geometry around ruthenium metal, marked by near-90° values for angles between the “legs”. The η5 coordination mode of the Cp ligand and the coordinative behavior of the phosphanes are as expected and do not need further comments.15,31−33 Noteworthy for 19b is the new pyrazoline ligand. The 5-phenyl-5-(p-tolyl)-3-cyano-1Hpyrazoline ligand is bonded to the metal through an sp2 nitrogen atom labeled N(1), and the geometrical parameters confirm the proposed formulation as a 1H-pyrazoline ligand and the singlebond character of the N−N bond. That is, the N−N bond length, 1.379(3) Å, is longer than that expected for a pyrazole ring34 but much longer than that found in the spiro[fluorene-9,3′pyrazoline] ligand,10 at 1.241(4) Å, or in 23c, with a value of 1.260(4) Å (see below). The sp3 N(2) atom is also bonded to carbon, N(2)−C(3), with a bond length of 1.502(3) Å, a single bond, and also to a hydrogen atom found clearly out of plane on the density map. However, the donor sp2 N(1) atom is bonded to the carbon, N(1)−C(5), with a bond length of 1.309(3) Å, the expected distance for a delocalized bond.34 The C(5)−C(6) distance of 1.421(3) Å is only slightly shorter than that expected for a single bond. The presence of the CN group as a substituent of the ring explains the electronic delocalization over the NC−CN−N moiety in the ring (Figure 2). The pyrazoline ring is not planar and has a twisted-envelope conformation, with puckering parameters Q = 0.213(3) Å and φ = 249.9(7)°.35 The rms deviation of the five atoms from the best plane is 0.095 Å, with a maximum of 0.128(2) Å for the atom

Unlike 4,5-dihydro-3H-pyrazole in complexes 6−9, the 1Hpyrazoline molecule 23 can be removed from the complex and recovered as an oil. Characterization of Complexes 17−22. 1H-Pyrazoline derivatives [Ru(η5-C5H5){η1-NC(CN)CH2C(Ar1Ar2)NH}(PPh3)(L)]BPh4 (19, 20) and η2-alkene complexes [Ru(η5C5H5){η2-RC(H)C(H)R}(PPh3)(L)]BPh4 (17, 18, 21, 22) were isolated as yellow or orange solids stable in air and in solution of polar organic solvents, where they behave as 1:1 electrolytes.23 Their characterization has been supported by analytical and spectroscopic IR and NMR data and by X-ray crystal structure determinations of [Ru(η5-C5H5)(η2-CH3CH CH2)(PPh3){P(OMe)3}]BPh410 (17), [Ru(η5-C5H5){η1-N C(CN)CH 2 C(Ph)(p-tolyl)NH}(PPh 3 ){P(OMe) 3 }]BPh 4 (19b), and [Ru(η5-C5H5){η2-CHCHC(O)OC(O)}(PPh3){P(OMe)3}]BPh4 (21), the ORTEP drawings30 of which are shown in Figures 1, 3, and 4, respectively. 3578

dx.doi.org/10.1021/om500481d | Organometallics 2014, 33, 3570−3582

Organometallics

Article

Figure 2. Atoms involved in the electronic delocalization.

labeled C(3), which is phenyl- and tolyl-substituted. The ruthenium atom is situated only 0.117(5) Å out of this plane, and the Ru−N bond forms an angle of only 1.83(15)° with the plane. The cyanide group also belongs to this plane, with distances of only 0.083(6) Å for C(6) and 0.116(7) Å for N(11), confirming the sp2 character of C(5). Compound 21 contains one η2-maleic anhydride (η2-ma) ligand as the third leg of the piano-stool structure (Figure 3). Figure 4. ORTEP view of the cation of 21 showing the disposition of η2-ma ligand.

(diphenylphosphino)methane), 39 Ru(η 2 -ma)(CO)(CN-ptolyl)(PPh3)2,36 and Os(η2-ma)(CO)2(PPh3)2.40 This may indicate scarce π back-bonding by the metal. However, the hydrogen atoms deviate by 0.39(6) and 0.35(6) Å out of the plane with respect to the maleic anhydride ring (C4O) and are sometimes even much farther: e.g., 0.49 and 0.61 Å in the iron compound Fe(CO)2(η2-ma)[2-pyridylbis(diphenylphosphino)methane].39 To the best of our knowledge,41 the literature only reports one 2 (η -ma)ruthenium complex, the Ru(0) species Ru(η2-ma)(CO)(CN-p-tolyl)(PPh3)2,36 and a dinuclear compound with the substituted 2,3-bis(diphenylphosphino)maleic anhydride, Ru2(CO)6(bma),42 is also known; thus, 21 is the first structurally characterized (η2-ma)ruthenium(II) complex. The IR spectra of the 1H-pyrazoline complexes [Ru(η5-

Figure 3. ORTEP view of the cation of 21. P(1) represents a PPh3 ligand, and P(2) represents a P(OMe)3 ligand. Only the hydrogen atoms of the η2-ma ligand are shown. Selected bond lengths (Å) are as follows: Ru−CT1, 1.8928(6); Ru−CT2, 2.0675(7); Ru−P(1), 2.3686(18); Ru− P(2), 2.2824(19); Ru−C(12), 2.182(8); Ru−C(13), 2.179(8). Cp ring: Ru−C(1), 2.227(6); Ru−C(2), 2.267(7); Ru−C(3), 2.270(6); Ru− C(4), 2.243(7); Ru−C(5), 2.184(7). Selected bond angles (deg): P(1)−Ru−P(2), 90.53(6); CT1−Ru−P(1), 119.92(5); CT1−Ru− P(2), 115.72(5); CT1−Ru−CT2, 129.57(3); CT2−Ru−P(1), 94.95(5); CT2−Ru−P(2), 97.56(6). CT1 represents the centroid of the Cp ligand; CT2 represents the middle of the C(12)−C(13) bond.

C 5 H 5){η 1 -NC(CN)CH 2 C(Ar1Ar2)NH}(PPh 3 )(L)]BPh4 (19, 20) show weak bands at 2213−2207 cm−1, attributed to νCN of the azo ligand. Apart from the signals of the ancillary ligands PPh3, P(OR)3, Cp, and BPh4 anion, the 1H NMR spectra of 19b and 20b, obtained as a mixture of diastereoisomers, show only one multiplet between 7.29 and 3.31 ppm, which can be simulated with an ABC model and can be attributed to the CH2 and NH hydrogen atoms of the 1H-pyrazoline. The 13C spectra support the presence of the azo ligand, showing two sets of signals for each carbon resonance C3, C4, C5 and CN; the 31P NMR spectra display two AB multiplets, matching the proposed formulation. The 1H NMR spectrum of 19c, which contains fluorene (C12H8) as a substituent, shows the expected ABC multiplet for the CH2 and NH protons of the pyrazoline ligand, and the 31P spectrum shows only one AB multiplet. The NMR spectra of the propylene derivatives [Ru(η5C5H5)(η2-CH3CHCH2)(PPh3)(L)]BPh4 (17, 18) confirm the presence of two diastereoisomers. In particular, at room temperature, the proton spectra show two sets of signals for the propylene hydrogen atoms, which were simulated with an ABCD3XY model (X, Y = 31P) with the parameters reported in the Experimental Section. The 31P NMR spectra exhibit two AB multiplets, whereas the 13C spectra show two sets of signals for the carbon atoms of both ancillary ligands and propylene, fitting a geometry like those found in the solid state.10

The η5 coordination mode of the Cp ligand shows Ru−C bond distances between 2.184(7) and 2.270(6) Å, the shorter one (C(5) atom) corresponding to that trans to the η2-olefin ligand. It should be noted that the difference between maximum and minimum Ru−C bond lengths is almost 0.1 Å. These differences in related complexes are about 0.05 Å. Coordination of the maleic anhydride (ma) occurs in such a way that its plane is almost perpendicular to the Ru−Ct2 bond, with an angle of 105.6°. The planes defined by the metal and the alkene carbon atoms (metallacyclopropane ring) and by the maleic anhydride ligand make a dihedral angle of 104.9(3)°, similar to the value of 107° found in the Ru(0) compound Ru(η2-ma)(CO)(CN-ptolyl)(PPh3)236 (see Figure 4). The CC bond length of 1.387(11) Å is only slightly longer than in the uncoordinated olefin (1.3322(9) Å)37 and clearly shorter than those usually found for coordinated η2-maleic anhydride in palladium complexes38 or other zerovalent iron triad complexes, such as Fe(CO) 2 (η 2 -ma)(2-pyridylbis3579

dx.doi.org/10.1021/om500481d | Organometallics 2014, 33, 3570−3582

Organometallics

Article

The IR spectrum of maleic anhydride complex [Ru(η5C5H5)(η2-ma)(PPh3){P(OMe)3}]BPh4 (21) shows two strong bands at 1826 and 1763 cm−1, attributed to νCO of the coordinated anhydride. The 1H NMR spectra confirm the presence of this ligand, showing two multiplets at 4.23 and 4.02 ppm, which can be simulated with an ABXY model (A, B = 31P) and can be attributed to the CH protons of the maleic anhydride. In the 13C spectra, the carbon resonances of these CH groups appear as doublets at 46.05 and 43.14 ppm, whereas two singlets at 172. 76 and 171.69 ppm can be attributed to the carbonyl groups, fitting the proposed formulation. Two strong νCO bands at 1746 and 1722 cm−1 appear in the infrared spectra of the dimethyl maleate complex [Ru(η5C 5 H 5 ){η 2 -CH 3 OCOC(H)C(H)COOCH 3 }(PPh 3 ){P(OMe)3}]BPh4 (22), attributed to the two CO groups of the methyl esters. The 1H NMR spectrum shows two multiplets at 3.62 and 3.32 ppm, which could be simulated with an ABXY model (A, B = 31P) and can be attributed to the two CH proton resonances. The spectra also show two singlets at 3.77 and 3.72 ppm of the methyl group of COOMe substituents, whereas in the 13C spectra both carbonyl and methyl carbon resonances appear as two singlets at 173.21 and 170.61 ppm and at 52.62 and 53.32 ppm, respectively. Instead, the two olefinic CH resonances appear as two doublets at 54.08 and 46.74 ppm, although the 31P spectrum shows an AB quartet, fitting the proposed formulation for the complex. Reactions with Alkynes. The results with alkenes prompted us to extend study of diazoalkane complexes 2−5 to terminal alkynes (Scheme 7).

Surprisingly, at room temperature, neither phenyl- nor tertbutylacetylene (HCCR) react with diazoalkane complexes 1−5, and the starting material can be recovered unchanged. Instead, under reflux conditions, the reaction proceeds to give vinylidene complexes [Ru(η5-C5H5){CC(H)R}(PPh3){P(OMe)3}]BPh4 (25, 26), which were isolated and characterized. Substitution of the diazoalkane probably gives rise to the η2-alkyne complex, which undergoes the known tautomerization43−45 of the coordinated HCCR to yield the final vinylidene derivative. The absence of cyclization of phenyl- and tert-butylacetylene prompted us to extend our study to activated alkynes such as alkyl propiolates HCCCOOR1. In this case, the reaction pro-

Scheme 7. a

NC(Ar1Ar2)C(H)C(R)}(PPh3){P(OMe)3}]BPh4 (24, 27, 28) were separated as orange solids stable in air and in solution of polar organic solvents, where they behave as 1:1 electrolytes.23 Their characterization is supported by analytical and spectroscopic (IR, NMR) data and by an X-ray crystal structure deter-

ceeds to give 3H-pyrazole derivatives [Ru(η5-C5H5){η1-N NC(Ar1Ar2)C(H)C(COOR1)}(PPh3 ){P(OMe)3}]BPh4 (27, 28), formed by dipolar (3 + 2) cycloaddition of the alkyne to the coordinated diazoalkane. These results highlight the important influence of substituents on the terminal alkyne in determining the cyclization reaction, which proceeds to give 3H-pyrazole derivatives with both acetylene (HCCH) and alkynes bearing an electron-withdrawing group, whereas only substitution of the diazoalkane and formation of vinylidene takes place with alkynes containing bulky groups (Ph, tBu) with electron-donor properties. Parallel behavior was observed with alkenes, indicating that the coordinated diazoalkane may easily undergo (3 + 2) cycloaddition under mild conditions with ethylene, acetylene, and related activated substrates. The new 3H-pyrazole complexes [Ru(η5-C5H5){η1-N

mination of the complex [Ru(η5-C5H5){η1-NNC(C12H8)C(H)C(H)}(PPh3){P(OMe)3}]BPh4 (24c), whose ORTEP30 plot is shown in Figure 5. The ruthenium cation complex in 24c also consists of a ruthenium atom coordinated by a Cp group, two phosphane ligands (one PPh3 and one P(OMe)3), and a new ligand, spiro[fluorene9,3′-pyrazole], bound to the Ru center via the nitrogen atom. This ligand is closely related to a spiro-pyrazoline ligand previously described by our group10 and also to 19b (see above) with a 1H-pyrazoline ligand. The most noteworthy characteristic of the new ligand in 24c is the short N−N bond distance in the pyrazole ring, 1.260(4) Å, which is slightly longer than that found in the related pyrazoline ring, 1.241(4) Å,10 but shorter than the expected value for free pyrazole, 1.366 Å,34 or for other pyrazole ruthenium complexes [RuCl(p-cymene)(Me2HPz)(PPh2OH)]+, 1.341(4) Å,46 confirming the double-bond character for this bond. The C−C and C−N bond distances in the pyrazole ring are all in the normal range for pyrazole rings (in particular, the C(4)−C(5) bond length (1.313(6) Å) is shorter than that found in the pyrazoline ring). However, as observed in the spiro[fluorene-9,3′pyrazoline] compound,10 the fluorene ring is essentially planar (rms deviation of 0.0843 Å), with dihedral angles between sixmembered rings and the central five-membered ring of 4.9(3)°. The pyrazole ring (which this time is planar as expected, with an rms deviation of 0.0146 Å, quite different from that found in pyrazoline complexes) is situated almost perpendicular to the fluorene plane, forming a dihedral angle of 85.9(1)°.

a

Definitions: L = P(OMe)3; Ar1 = Ph and Ar2 = p-tolyl (b), Ar1Ar2 = C12H8 (c); R = Ph (25), But (26); R1 = Me (27), Et (28).

Under mild conditions (1 atm, room temperature), acetylene quickly reacts with diazoalkane complexes 2 to give the 3H-pyrazole complex [Ru(η5-C5H5){η1-NNC(Ar1Ar2)C(H)C(H)}(PPh3){P(OMe)3}]BPh4 (24), which was isolated in good yield and characterized. The reaction proceeds with (3 + 2) cycloaddition of the acetylene to the coordinate diazoalkane, giving the 3H-pyrazole derivative 24, in which the heterocycle acts as a ligand. This reaction parallels that observed with ethylene, but in this case no substitution was observed, as cyclization was almost quantitative. 3580

dx.doi.org/10.1021/om500481d | Organometallics 2014, 33, 3570−3582

Organometallics

Article

temperature) and activated alkynes HCCCOOR1, affording 3H-pyrazole complexes, whereas substitution of the diazoalkane and formation of vinylidene derivatives [Ru]CC(H)R occur with phenyl- and tert-butylacetylene.

■

ASSOCIATED CONTENT

* Supporting Information S

Table S1 and CIF files giving crystallographic data for 19b, 21, and 24c. This material is available free of charge via the Internet at http://pubs.acs.org.

■

Figure 5. ORTEP view of the cation of 24c. P(1) represents a PPh3 ligand, and P(2) represents a P(OMe)3 ligand. Only the hydrogen atoms of the pyrazole ligand are shown. Selected bond lengths (Å) are as follows. Ru−CT1, 1.8803(9); Ru−N(1), 2.065(3); Ru−P(1), 2.3608(16); Ru−P(2), 2.2216(16). Cp ring: Ru−C(1), 2.209(5); Ru−C(2), 2.224(4); Ru−C(3), 2.234(5); Ru−C(4), 2.232(4); Ru− C(5), 2.219(4). C3N2 ring: N(1)−N(2), 1.260(4); N(1)−C(5), 1.452(5); N(2)−C(3), 1.497(5); C(4)−C(5), 1.313(6); C(3)−C(4), 1.473(6). Selected bond angles (deg): P(1)−Ru−P(2), 92.90(5); CT1−Ru−P(1), 123.88(3); CT1−Ru−P(2), 121.75(5); CT1−Ru− N(1), 125.90(9); N(1)−Ru−P(2), 89.53(10); N(1)−Ru−P(2), 93.57(10). CT1 represents the centroid of the Cp ligand.

AUTHOR INFORMATION

Corresponding Author

*E-mail for G.A.: [email protected]. Notes

The authors declare no competing financial interest.

■ ■

ACKNOWLEDGMENTS Thanks go to Mrs. Daniela Baldan, from the Università Ca’ Foscari Venezia, Venezia, Italy, for her technical assistance. REFERENCES

(1) Dartiguenave, M.; Menu, M. J.; Deydier, E.; Dartiguenave, Y.; Siebald, H. Coord. Chem. Rev. 1998, 178−180, 623−663. (2) (a) Herrmann, W. A. Angew. Chem., Int. Ed. 1978, 17, 800−812. (b) Doyle, M. P. Chem. Rev. 1986, 86, 919−939. (c) Roper, W. R. J. Organomet. Chem. 1986, 300, 167−190. (d) Putala, M.; Lemenovskii, D. A. Russ. Chem. Rev. 1994, 63, 197−216. (e) Werner, H. J. Organomet. Chem. 1995, 500, 331−336. (f) Mizobe, Y.; Ishii, Y.; Hidai, M. Coord. Chem. Rev. 1995, 139, 281−311. (g) Kirmse, W. Angew. Chem., Int. Ed. 2003, 42, 1088−1093. (3) (a) Schwab, P.; Grubbs, R. H.; Ziller, J. W. J. Am. Chem. Soc. 1996, 118, 100−110. (b) Fürstner, A. Angew. Chem., Int. Ed. 2000, 39, 3012− 3043. (c) Grubbs, R. H. Angew. Chem., Int. Ed. 2006, 45, 3760−3765. (d) Schrock, R. R. Angew. Chem., Int. Ed. 2006, 45, 3748−3759. (4) (a) Sutton, D. Chem. Rev. 1993, 93, 995−1022. (b) Hidai, M.; Mizobe, Y. Chem. Rev. 1995, 95, 1115−1133. (5) (a) Kisch, H.; Holzmeier, P. Adv. Organomet. Chem. 1992, 34, 67− 109. (b) Sellmann, D. Angew. Chem., Int. Ed. 1993, 32, 64−67. (c) Zollinger, H. Diazo Chemistry II; VCH: Weinheim, Germany, 1995. (6) (a) Ben-Shoshan, R.; Chatt, J.; Leigh, G. J.; Hussain, W. J. Chem. Soc., Dalton Trans. 1980, 771−775. (b) Hidai, M.; Aramaki, S.; Yoshida, K.; Kodama, T.; Takahashi, T.; Uchida, Y.; Mizobe, Y. J. Am. Chem. Soc. 1986, 108, 1562−1568. (7) (a) Nakamura, A.; Yoshida, T.; Cowie, M.; Otsuka, S.; Ibers, J. A. J. Am. Chem. Soc. 1977, 99, 2108−2117. (b) Schramm, K. D.; Ibers, J. A. Inorg. Chem. 1980, 19, 1231−1236. (c) Schramm, K. D.; Ibers, J. A. Inorg. Chem. 1980, 19, 2435−2440. (d) Schramm, K. D.; Ibers, J. A. Inorg. Chem. 1980, 19, 2441−2448. (e) Hillhouse, G. L.; Haymore, B. L. J. Am. Chem. Soc. 1982, 104, 1537−1548. (f) Cowie, M.; Loeb, S. J.; McKeer, I. R. Organometallics 1986, 5, 854−865. (g) Kaplan, A. W.; Polse, J. L.; Ball, G. E.; Andersen, R. A.; Bergman, R. G. J. Am. Chem. Soc. 1998, 120, 11649−11662. (h) Kwen, H.; Young, V. G., Jr.; Maatta, E. A. Angew. Chem., Int. Ed. 1999, 38, 1145−1146. (i) Dias, E. L.; Brookhart, M.; White, P. S. J. Am. Chem. Soc. 2001, 123, 2442−2443. (j) Werner, H.; Mahr, N.; Wolf, J.; Fries, A.; Laubender, M.; Bleuel, E.; Garde, R.; Lahuerta, P. Organometallics 2003, 22, 3566−3576. (8) (a) Messerle, L.; Curtis, M. D. J. Am. Chem. Soc. 1980, 102, 7789− 7791. (b) Woodcock, C.; Eisenberg, R. Organometallics 1985, 4, 4−7. (c) Curtis, M. D.; Messerle, L.; D’Errico, J. J.; Butler, W. M.; Hay, M. S. Organometallics 1986, 5, 2283−2294. (d) Gao, Y.; Jennings, M. C.; Puddephatt, R. J.; Jenkins, H. A. Organometallics 2001, 20, 3500−3509. (e) Rowsell, B. D.; Trepanier, S. J.; Lam, R.; McDonald, R.; Cowie, M. Organometallics 2002, 21, 3228−3237. (f) Cohen, R.; Rybtchinski, B.; Gandelman, M.; Rozenberg, H.; Martin, J. M. L.; Milstein, D. J. Am. Chem. Soc. 2003, 125, 6532−6546. (g) Bart, S. C.; Bowman, A. C.;

In addition to the signals of the ancillary ligands Cp and phosphanes, the 1H NMR spectra of [Ru(η5-C5H5){η1-N NC(Ar1Ar2)C(H)C(H)}(PPh 3){P(OMe) 3 }]BPh 4 (24) show two doublets at 7.62−6.82 ppm, attributed to the H4 and H5 protons of the heterocycle, and the characteristic signals of the substituents at C3. The 13C spectra confirm the proposed formulation, showing the Cp signal at 85.21−84.96 ppm, those of the methyl of P(OMe)3 at 53.30−53.08 ppm, and three singlets at 105.18−104.09, 141.16−145.55, and 155.24−152.71 ppm, attributed respectively to the C3, C4, and C5 carbon resonances of the 3H-pyrazole ligand. The IR spectra of vinylidene derivatives [Ru(η5-C5H5){ CC(H)R}(PPh3)(L)]BPh4 (25, 26) show a medium-intensity band at 1675−1644 cm−1 attributed to νRuCC of the vinylidene. However, the 13C NMR spectra are diagnostic for the presence of the CαCβ(H)R ligand, showing a doublet of doublets at 359.28 (25a) and 353.07 ppm (25b), attributed to the carbene carbon resonance Cα, and singlets at 118.34 (25a) and 124.86 ppm (25b) of Cβ. The 1H NMR spectra show a multiplet at 5.57−4.31 ppm which, in an HMQC experiment, was correlated with the singlet at 118−124 ppm observed in the 13 C spectra and was attributed to the vinylidene hydrogen atom Cβ(H)R, whereas the 31P spectra appear as an AB quartet, fitting the proposed formulation for vinylidene complexes.

■

CONCLUSIONS This study reports that diazoalkane molecules coordinated to the half-sandwich fragment [Ru(η5-C5H5)(PPh3)(L)]+ undergo unprecedented dipolar (3 + 2) cycloaddition with ethylene (CH2CH2) under mild conditions (1 atm, room temperature) to afford dihydro-3H-pyrazole derivatives. Acrylonitrile (CH2 CHCN) also gives cycloaddition to coordinated Ar1Ar2CN2 but yields 1H-pyrazoline derivatives. Substitution of the diazoalkane was also observed, yielding η2-alkene complexes. The influence of the steric and electronic factors of the substituents on the alkene in leading to cycloaddition vs a substitution process was partially clarified. Dipolar cycloaddition was also observed with both acetylene (HCCH) under mild conditions (1 atm, room 3581

dx.doi.org/10.1021/om500481d | Organometallics 2014, 33, 3570−3582

Organometallics

Article

Lobkovsky, E.; Chirik, P. J. J. Am. Chem. Soc. 2007, 129, 7212−7213. (h) Samant, R. G.; Graham, T. W.; Rowsell, B. D.; McDonald, R.; Cowie, M. Organometallics 2008, 27, 3070−3081 and references therein. (i) Zhang, J.; Gandelman, M.; Shimon, L. J. W.; Milstein, D. Organometallics 2008, 27, 3526−3530. (j) Mankad, N. P.; Peters, J. C. Chem. Commun. 2008, 1061−1063. (k) Russell, S. K.; Lobkovsky, E.; Chirik, P. J. J. Am. Chem. Soc. 2009, 131, 36−37. (l) Khosla, C.; Jackson, A. B.; White, P. S.; Templeton, J. L. Organometallics 2012, 31, 987−994. (m) Egloff, J.; Ranocchiari, M.; Schira, A.; Schotes, C.; Mezzetti, A. Organometallics 2013, 32, 4690−4701. (9) (a) Albertin, G.; Antoniutti, S.; Bordignon, E.; Carrera, B. Inorg. Chem. 2000, 39, 4646−4650. (b) Albertin, G.; Antoniutti, S.; Callegaro, F.; Castro, J. Organometallics 2009, 28, 4475−4479. (10) Albertin, G.; Antoniutti, S.; Baldan, D.; Comparin, G.; Castro, J. Organometallics 2013, 32, 3157−3160. (11) Rabinowitz, R.; Pellon, J. J. Org. Chem. 1961, 26, 4623−4626. (12) (a) Smith, L. I.; Howard, K. L. Organic Syntheses; Wiley: New York, 1955; Collect. Vol. III, p 351. (b) Miller, J. B. J. Org. Chem. 1959, 24, 560−561. (c) Baltzly, R.; Mehta, N. B.; Russell, P. B.; Brooks, R. E.; Grivsky, E. M.; Steinberg, A. M. J. Org. Chem. 1961, 26, 3669−3676. (13) Balacco, G. http://www.inmr.net/. (14) (a) Bruce, M. I.; Windsor, N. J. Aust. J. Chem. 1977, 30, 1601− 1604. (b) Ashby, G. S.; Bruce, M. I.; Tomkins, I. B.; Wallis, R. C. Aust. J. Chem. 1979, 32, 1003−1016. (c) Rottink, M. K.; Angelici, R. J. J. Am. Chem. Soc. 1993, 115, 7267−7274. (15) Albertin, G.; Antoniutti, S.; Bacchi, A.; Pelizzi, G.; Zanardo, G. Organometallics 2008, 27, 4407−4418. (16) SMART version 5.054, Instrument control and data collection software; Bruker AXS Inc., Madison, WI, USA, 1997. (17) APEX2; Bruker AXS Inc., Madison, WI, USA, 2007. (18) SAINT version 6.01, Data Integration software package; Bruker AXS Inc., Madison, WI, USA, 1997. (19) Sheldrick, G. M. SADABS, a Computer Program for Absorption Corrections.; University of Göttingen, Göttingen, Germany, 1996. (20) McArdle, P. J. Appl. Crystallogr. 1995, 28, 65−65. (21) Sheldrick, G. M. Acta Crystallogr. 2008, A64, 112−122. (22) Palatinus, L.; Chapuis, G. J. Appl. Crystallogr. 2007, 40, 786−790. (23) Geary, W. J. Coord. Chem. Rev. 1971, 7, 81−122. (24) For 1,3-dipolar cycloaddition see: (a) Huisgen, R. Angew. Chem., Int. Ed. Engl. 1963, 2, 565−632. (b) Adam, W.; De Lucchi, O. Angew. Chem., Int. Ed. Engl. 1980, 19, 762−779. (c) 1,3-Dipolar Cycloaddition Chemistry; Padwa, A., Ed.; Wiley: New York, 1984; Vol. 1. (d) Padwa, A. In Comprehensive Organic Synthesis, Trost, B. M., Fleming, I., Eds.; Pergamon Press: Oxford, U.K., 1991; Vol. 4, pp 1069−1109. (e) Diederich, F.; Isaacs, L.; Philip, D. Chem. Soc. Rev. 1994, 23, 243− 255. (f) Sibi, M. P.; Stanley, L. M.; Soeta, T. Org. Lett. 2007, 9, 1553− 1556 and references therein. (25) Conlin, R. T.; Kwak, Y.-W. J. Organomet. Chem. 1985, 293, 177− 183. (26) White, D. H.; Condit, P. B.; Bergman, A. G. J. Am. Chem. Soc. 1972, 94, 1348−1350. (27) (a) McGreer, D. E.; McDaniel, R. S.; Vinje, M. G. Can. J. Chem. 1965, 43, 1389−1397. (b) Crawford, R. J.; Mishra, A. J. Am. Chem. Soc. 1966, 88, 3963−3969. (c) McGreer, D. E.; Wu, W.-S. Can. J. Chem. 1967, 45, 461−468. (d) Allred, A. L.; Smith, R. L. J. Am. Chem. Soc. 1967, 89, 7133−7134. (e) Al-Sader, B. H.; Crawford, R. J. Can. J. Chem. 1968, 46, 3301−3304. (28) (a) Moore, R.; Mishra, A.; Crawford, R. J. Can. J. Chem. 1968, 46, 3305−3313. (b) Wiberg, K. B.; deMeijere, A. Tetrahedron Lett. 1969, 59−62. (29) Deydier, E.; Menu, M.-J.; Dartiguenave, M.; Dartiguenave, Y.; Simard, M.; Beauchamp, A. L.; Brewer, J. C.; Gray, H. B. Organometallics 1996, 15, 1166−1175. (30) Farrugia, L. J. J. Appl. Crystallogr. 1997, 30, 565−565. (31) Albertin, G.; Antoniutti, S.; Castro, J.; Scapinello, F. J. Organomet. Chem. 2014, 751, 412−419. (32) Joslin, F. L.; Mague, J. T.; Roundhill, D. M. Organometallics 1991, 10, 521−524.

(33) Chang, C.-W.; Lin, Y.-C.; Lee, G.-H.; Huang, S.-L.; Wang, Y. Organometallics 1998, 17, 2534−2542. (34) Allen, F. H.; Kennard, O.; Watson, D. G.; Brammer, L.; Orpen, A. G.; Taylor, R. J. Chem. Soc., Perkin Trans. 2 1987, S1−S19. (35) The Q parameter gives the amplitude of the puckering; φ indicates either an envelope distortion, if φ = 36n, or an half-chair form, if φ = 36n + 18. See: Cremer, D.; Pople, J. A. J. Am. Chem. Soc. 1975, 97, 1354−1358. (36) Rickard, C. E. F.; Roper, W. R.; Wright, L. J.; Young, L. J. Organomet. Chem. 1989, 364, 391−397. (37) Lutz, M. Acta Crystallogr., Sect. E 2001, E57, o1136−o1138. (38) (a) Canovese, L.; Visentin, F.; Levi, C.; Santo, C.; Bertolasi, V. Inorg. Chim. Acta 2012, 390, 105−118. (b) Nagele, P.; Herrlich, U.; Rominger, F.; Hofmann, P. Organometallics 2013, 32, 181−191. (39) Mague, J. T.; Krinsky, J. L. Inorg. Chem. 2001, 40, 1962−1971. (40) Burrell, A. K.; Clark, G. R.; Rickard, C. E. F.; Roper, W. R.; Ware, D. C. J. Organomet. Chem. 1990, 398, 133−158. (41) CCDC database, CSD version 5.34 (May 2013 updated). (42) Watson, W. H.; Chen, T.; Richmond, M. G. J. Chem. Crystallogr. 2004, 34, 797−805. (43) (a) Bruce, M. I. Chem. Rev. 1991, 91, 197−257. (b) Puerta, M. C.; Valerga, P. Coord. Chem. Rev. 1999, 193−195, 977−1025. (44) (a) Bullock, M. J. Chem. Soc., Chem. Commun. 1989, 165−167. (b) Esteruelas, M. A.; Oro, L. A.; Valero, C. Organometallics 1995, 14, 3596−3599. (c) de los Rios, I.; Jiménez Tenorio, M.; Puerta, M. C.; Valerga, P. J. Am. Chem. Soc. 1997, 119, 6529−6538. (45) (a) Silvestre, J.; Hoffmann, R. Helv. Chim. Acta 1985, 68, 1461− 1506. (b) Wakatsuki, Y.; Koga, N.; Werner, H.; Morokuma, K. J. Am. Chem. Soc. 1997, 119, 360−366. (46) Tribó, R.; Pons, J.; Yáñez, R.; Piniella, J. F.; Á lvarez-Larena, A.; Ros, J. Inorg. Chem. Commun. 2000, 3, 545−549.

3582

dx.doi.org/10.1021/om500481d | Organometallics 2014, 33, 3570−3582