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Apr 18, 2013 - ... 4 with GeCl2·(dioxane) and PbCl2 afforded the “open-box” 1,3-digermacyclobutane [Ge{μ2-C(iPr2P═S)(C9H6N-2)]2 (9) and “twi...
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Synthesis and Structural Characterization of Lithium, Potassium, Magnesium, and Heavier Group 14 Metal Complexes Derived from 2‑Quinolyl-Linked (Thiophosphorano)methane Wing-Por Leung,* Yuk-Chi Chan, and Thomas C. W. Mak Department of Chemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, People’s Republic of China S Supporting Information *

ABSTRACT: The synthesis and structural characterization of lithium, magnesium, potassium, and a series of low-valent group 14 metal compounds derived from the novel 2-quinolyl-linked phosphoranosulfide CH2(iPr2PS)(C9H6N-2) (3) are reported. The monoanionic thiophosphinoyl lithium complex [Li(Et2O){CH(iPr2P−S)(C9H6N-2)}]2 (4) and magnesium complex [Mg{CH(iPr2P−S)(C9H6N-2)}2] (5) have been prepared from the reaction of 3 with 1 equiv of nBuLi or 0.5 equiv of nBu2Mg in THF. Metathesis of 4 with 2 equiv of KtBuO afforded the corresponding polymeric thiophosphinoyl potassium complex [K{CH(iPr2P−S)(C9H6N-2)}]n (6). The metathesis reaction of 4 with GeCl2·(dioxane) and PbCl2 afforded the “open-box” 1,3digermacyclobutane [Ge{μ2-C(iPr2PS)(C9H6N-2)]2 (9) and “twisted-step” 1,3-diplumbacyclobutane [Pb{μ2-C(iPr2P S)(C9H6N-2)]2 (10), respectively. Reaction of 3 with 1 equiv of M{N(SiMe3)2}2 (M = Sn, Pb) afforded the corresponding “open-box” 1,3-distannacyclobutane [Sn{μ2-C(iPr2PS)(C9H6N-2)]2 (11) and [Pb{μ2-C(iPr2PS)(C9H6N-2)]2 (12), respectively. The structures of 3−6 and 9−12 have been determined by X-ray crystallography.

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relatively long metal−carbon bond distance.9−11 Nevertheless, thiophosphinoyl ligands have rarely been used as ancillary ligands in the synthesis of group 14 metal complexes. Recently, we have reported the synthesis of group 14 metal complexes derived from bis(diphenylthiophosphinoyl)methane and 2,6-lutidyl bis(phosphoranosulfide), respectively.12,13 The heavier analogues of allene 2-silaallene, 2-germaallene, and 2-stannaallene have been reported, which were also derived from bis(diphenylthiophosphinoyl)methane.14−16 Herein, we report the synthesis of a novel 2-quinolyl-linked (thiophosphorano)methane, which can be used to synthesize lithium, potassium, magnesium, and some low-valent heavier group 14 metal complexes.

INTRODUCTION The coordination chemistry of thiophosphinoyl transition-metal complexes has been studied by several research groups since the 1970s.1 Phosphoranosulfides R3PS can be deprotonated by a strong base to give anionic species, which can be used as ligands in the synthesis of organometallic compounds. An unprecedented organoaluminium compound was first reported by Robinson and co-workers through an in situ double deprotonation of neutral bis(diphenylthiophosphinoyl)methane, H2C(PPh2S)2, with AlMe3.2 Using the same phosphinoylmethane, Le Floch and co-workers reported the synthesis of a dianionic lithium complex of bis(diphenylthiophosphinoyl)methanediide.3 Afterward, stable Pd(II), Ru(II), Zr(IV), and Tm(III) metal carbenoids and dicarbenoids were prepared from the dianion derived from bis(diphenylthiophosphinoyl)methane.4−8 By using the dilithium complex as a ligand transfer reagent, various lanthanide and actinide metal carbene complexes have been successfully synthesized. Theoretical calculations on these carbene complexes suggested that the metal−carbon double-bond character is relatively weak and the π bond is strongly polarized toward the carbon atom, resulting in a © 2013 American Chemical Society

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RESULTS AND DISCUSSION Synthesis of 2-Quinolyl-Linked (Thiophosphorano)methane. Treatment of 2-methylquinoline (C9H6N-2) with 1 equiv of nBuLi in the presence of TMEDA, followed by the Received: January 28, 2013 Published: April 18, 2013 2584

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Scheme 1. Synthesis of Compound 3

3 with 2 equiv of KtBuO in THF gave the polymeric 2-quinolyllinked potassium (thiophosphinoyl)methanide complex [K{CH(iPr2P−S)(C9H6N-2)}]n (6) (Scheme 3). Synthesis of 2-Quinolyl-Linked 1,3-Digermacyclobutane, 1,3-Distannacyclobutane, and 1,3-Diplumbacyclobutane. Reaction of 4 with 1 equiv of GeCl2.(dioxane) or 1 equiv of PbCl2 in THF gave the “open-box” 1,3-digermacyclobutane and “twisted-step” 1,3-diplumbacyclobutane. We suggest that a possible mechanism could be that 0.5 equiv of 4 reacted with 1 equiv of MCl2 (M = Ge, Pb) to give the intermediate heteroleptic metal(II) chloride 7. A further dehydrochlorination reaction of 7 with another 0.5 equiv of 4 accompanied by the elimination of LiCl gave the unstable intermediate metallavinylidene [:MC(iPr2PS)(C9H6N-2)] (8; M = Ge, Pb), which then underwent a “head-to-tail” cyclodimerization to give the 1,3-digermacyclobutane [Ge{μ2-C(iPr2PS)(C9H6N-2)]2 (9) and [Pb{μ2-C(iPr2PS)(C9H6N-2)]2 (10), respectively (Scheme 4). It is believed that 4 acted as a ligand-transfer reagent as well as a strong base for dehydrochlorination to form 9 and 10. Similar dehydrochlorinations have been reported in the synthesis of bis(germavinylidene) from the reaction of GeCl2·(dioxane) with [Li{CH(PPh2NSiMe3)2}(THF)]17 and group 13 bis(thiophosphinoyl)methanediide metal complexes from the reaction of MCl3 (M = Al, Ga, In) with [Li{CH(PPh2 S)2(Et2O)(THF)}].18 Attempts to synthesize compound 9 with 1 equiv of Ge{N(SiMe 3 ) 2 }2 were not successful; only CH2(iPr2PS)(C9H6N-2) was isolated from the reaction mixture. Reaction of 3 with 1 equiv of M{N(SiMe3)2}2 (M = Sn, Pb) afforded the corresponding “open-box” 1,3-distannacyclobutane [Sn{μ2-C(iPr2PS)(C9H6N-2)]2 (11) and [Pb{μ2-C(iPr2P S)(C9H6N-2)]2 (12), respectively (Scheme 5). We proposed that a possible mechanism could be that the reactions proceed through the unstable metallavinylidenes [:MC(iPr2PS)(C9H6N-2)] (8; M = Sn, Pb) with the elimination of 2 equiv of hexamethyldisilazane, followed by a head-to-tail cyclodimerization to form the 1,3-dimetallacyclobutane. Compound 10 was isolated as a “twisted-step” structure, while compound 12 was isolated as an “open-box” structure. It is believed that different solvent properties contributed to the isolation of different

addition of chlorodiisopropylphosphine, afforded the corresponding diphosphine CH2(iPr2P)(C9H6N-2) (2). Further treatment of phosphine 2 with elemental sulfur in THF at 60 °C afforded the novel 2-quinolyl-linked (thiophosphorano)methane CH2(iPr2PS)(C9H6N-2) (3) (Scheme 1). Compound 3 was isolated as a white crystalline solid after recrystallization from THF. Synthesis of Monoanionic 2-Quinolyl-Linked Lithium (Thiophosphinoyl)methanide Complex and Magnesium Bis(thiophosphinoyl)methanide Complex. The reaction of 3 with 1 equiv of nBuLi in THF gave the dimeric 2-quinolyllinked lithium (thiophosphinoyl)methanide complex [Li(Et2O){CH(iPr2P−S)(C9H6N-2)}]2 (4). A similar reaction of 3 with 0.5 equiv of nBu2Mg in THF afforded the 2-quinolyl-linked magnesium bis(thiophosphinoyl)methanide complex [Mg{CH(iPr2P−S)(C9H6N-2)}2] (5) (Scheme 2). Scheme 2. Synthesis of Compounds 4 and 5

Synthesis of Monoanionic 2-Quinolyl-Linked Potassium (Thiophosphinoyl)methanide Complex. Metathesis of Scheme 3. Synthesis of Compound 6

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Scheme 4. Synthesis of Compounds 9 and 10

Scheme 5. Synthesis of Compounds 11 and 12

structures of [Pb{μ2-C(iPr2PS)(C9H6N-2)]2. Similar results have been reported in the isolation of 1,3-distannacyclobutane with 2-pyridyl-linked (iminophosphosphorano)methane as the supporting ligand.21 We have reported the synthesis of similar

1,3-dimetallacyclobutanes using phosphoranoimine as the ligand backbone.19−21 Spectroscopic Properties. Compounds 3−6 and 9−12 were isolated as air- and moisture-sensitive colorless, orange, and 2586

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red crystalline solids. They have been characterized by multinuclear NMR spectroscopy and elemental analysis. The 1 H NMR and 13C{1H} NMR spectra of 3−6 are consistent with the compounds having a 2-quinolyl ligand backbone. The 1H NMR and 13C{1H} NMR spectra of 3 are normal and are consistent with the solid-state structure. Furthermore, the 31 1 P{ H} NMR spectra of 4−6 displayed one signal at δ 51.7, 51.0, and 53.5 ppm, respectively, which are also consistent with structures having one phosphorus environment in 4−6. The 1H NMR and 13C{1H} NMR spectra of 9−12 are consistent with the compounds having the 2-quinolyl ligand backbone. The absence of methylene protons in 9−12 has been confirmed by 1H NMR. The 31P{1H} NMR spectra of 9 displayed one signal at δ 69.5 ppm, while 10 displayed two signals at δ 57.6 and δ 59.8 ppm with lead satellites (2J31P−207Pb = 68.0 and 63.2 Hz), respectively. This is due to two nonequivalent phosphorus nuclei present in 10. The 207Pb NMR spectrum also displayed two broad signals at δ 2189 (ν1/2 = 507 Hz) and δ 2647 (ν1/2 = 507 Hz) ppm; no resolvable 207Pb−31P coupling could be observed in the 207Pb{1H} NMR spectrum. This is comparable to the signal found in [{2-{Pb{C(iPr2PS)}}-6-{CH2(iPr2PS)}}C5H3N]2 (δ 2197 ppm).12 The 31P{1H} NMR spectrum of 11 displayed one signal at δ 61.8 ppm with tin satellites (2J31P−119Sn = 45.4 Hz), which suggests the two phosphorus nuclei are equivalent. The 119Sn{1H} NMR spectrum displayed one signal at δ −12.0 ppm with phosphorus satellites (2J31P−119Sn = 95.4 Hz), which is also consistent with one tin chemical environment. This is comparable to the 119Sn signals reported in [{2-{Sn{C(iPr2P S)}}-6-{CH2(iPr2PS)}}C5H3N]2 (δ −4.0 ppm)12 but relatively downfield in comparison to [Sn{μ2-C(Ph2PS)2}]2 (δ −129.6 ppm).13 The 31P{1H} NMR spectrum of 12 displayed two signals at δ 58.7 and δ 60.9 ppm with lead satellites (2J31P−207Pb = 66.4 and 61.6 Hz), respectively. This is due to the two nonequivalent phosphorus nuclei present in 12. The 207Pb NMR spectrum also displayed two signals at δ 2644 (ν1/2 = 152 Hz) and δ 2646 (ν1/2 = 152 Hz) ppm; no resolvable 207Pb−31P coupling could be observed in the 207Pb{1H} NMR spectrum. This is comparable to the 207Pb signal reported in [{2{Pb{C(iPr2PS)}}-6-{CH2(iPr2PS)}}C5H3N]2 (δ 2197 ppm).12 Low-temperature 31P NMR measurements of compounds 9−12 have been carried out; the signals remained unchanged, suggesting that no fluxional behavior is present in 9− 12. X-ray Structures. The molecular structures of compounds 4−6 and 9−12 are shown in Figures 1−7, respectively. Selected bond distances (Å) and angles (deg) of compounds 4−6 and 9− 12 are given in Table 1−3. Compound 4 is a centrosymmetric dimer in the solid state with Li2N2 rhombus and coordinating with two Et2O molecules (Figure 1). The lithium atom is bonded to the ligand in a N,S-chelating fashion and coordinated to one Et2O molecule with a distorted-tetrahedral geometry. The lithium atom is bonded to one sulfur atom and one nitrogen atom from the quinolyl ring to form a six-membered LiNCCPS metallacycle. The Li−Nquinolyl bond distance of 2.039(4) Å is comparable to those found in [Li{(S−PiPr2CH)(SPiPr2CH2)C5H3N-2,6}(Et2O)].12 The Li−S bond distances of 2.421(4) and 2.600(4) Å suggest that one of the Li−S bonds is a S→Li coordinate bond while the other is a Li−S σ bond. The Li−S bond distances in 4 are comparable to those found in [Li{(S− PiPr2CH)(SPiPr2CH2)C5H3N-2,6}(Et2O)] (2.393(1) and 2.556(2) Å).12 Compound 4 features an elongation of the P−S bond (2.009(9) Å) and a shortening of the P−C bond (1.733(2) Å) distance in comparison with those in the neutral ligand

Table 1. Selected Bond Distances (Å) and Angles (deg) for Compounds 4−6a [Li(Et2O){CH(iPr2P−S)(C9H6N-2)}]2 (4) Li(1)−N(1) 2.039(4) N(1)−C(9) Li(1)−O(1) 1.951(4) P(1)−S(1) Li(1)−S(1) 2.421(4) P(1)−C(10) Li(1)−S#(1) 2.600(4) O(1)−Li(1)−N(1) 106.5(2) N(1)−Li(1)−S#(1) O(1)−Li(1)−S(1) 115.2(2) S(1)−Li(1)−S#(1) O(1)−Li(1)−S#(1) 116.3(2) S(1)−P(1)−C(10) N(1)−Li(1)−S(1) 107.8(2) C(1)−N(1)−C(9) [Mg{CH(iPr2P−S)(C9H6N-2)}2] (5)

1.357(3) 2.009(9) 1.733(2)

Mg(1)−S(1) 2.435(9) P(1)−C(10) Mg(1)−S(2) 2.450(9) P(2)−S(2) Mg(1)−N(1) 2.076(2) P(2)−C(26) Mg(1)−N(2) 2.089(2) N(1)−C(9) P(1)−S(1) 2.020(9) N(2)−C(25) S(1)−Mg(1)−S(2) 106.5(2) N(1)−Mg(1)−N(2) S(1)−Mg(1)−N(1) 115.2(2) N(1)−Mg(1)−S(2) S(1)−Mg(1)−N(2) 116.3(2) S(1)−P(1)−C(10) S(2)−Mg(1)−N(2) 107.8(2) S(2)−P(2)−C(26) [K{CH(iPr2P−S)(C9H6N-2)}]n (6)

1.732(2) 2.016(9) 1.727(2) 1.365(3) 1.363(3) 99.4(8) 126.0(7) 116.9(9) 116.6(9)

K(1)−N(1) K(1)−S(1) K(1)−S#(1) N(1)−K(1)−S(1) N(1)−K(1)−S#(1) S(1)−K(1)−S#(1) P(1)−S(1)−K(1)

1.357(3) 1.995(1) 1.743(3) 84.1 (4) 78.5(3) 118.7(2)

2.825(2) 3.160(1) 3.301(1) 79.7(2) 76.6(5) 101.5(3) 101.0(4)

N(1)−C(9) P(1)−S(1) P(1)−C(10) P(1)−S(1)−K#(1) K(1)−S(1)−K#(1) C(1)−N(1)−C(9)

117.9(2) 92.7(1) 117.2(9) 119.4(2)

Symmetry transformations used to generate equivalent atoms: (#) −x + 2, y, −z + 3/2. a

CH2(iPr2PS)(C9H6N-2) (P−C = 1.828(2) Å and P−S = 1.961(6) Å), which is due to a dipolar resonance in the presence of the metal center.22 Compound 5 is a monomeric magnesium complex in the solid state (Figure 2). The magnesium atom is bonded to two monoanionic ligands in an N,S-chelating fashion with a distorted-tetrahedral geometry. The magnesium atom is bonded to two sulfur atoms and nitrogen atoms from the quinolyl ring to form two six-membered MgNCCPS metallacycles. The average Mg−Nquinolyl bond distance of 2.083 Å is comparable to those found in [Mg{(S−PiPr2CH)2C5H3N-2,6}].12 The average Mg− S bond distance of 2.443 Å is shorter than those found in [Mg{(S−PiPr2CH)2C5H3N-2,6}] (2.518 Å),12 [o-C6H11PS3Mg (THF) 2 ] (2.644 Å), 23 and [{MgOH}{(μ-S)(μ-N t BuP(NHtBu)2]6 (2.623 Å).24 Similar to the case for compound 4, compound 5 also features an elongation of the P−S bond (average 2.018 Å) and a shortening of the P−C bond distance (1.730 Å) in comparison with those of the neutral ligand CH2(iPr2PS)(C9H6N-2) (P−C = 1.828(2) Å and P−S = 1.961(6) Å), which is also due to a dipolar resonance in the presence of the metal center.22 From the solid-state structure of compound 5, it is noteworthy that there is a 3.310 Å aromatic πstacking interaction between the two quinolyl rings.25 Compound 6 is polymeric in the solid state (Figure 3). The potassium atom is bonded to the sulfur atom and nitrogen atom of the ligand and coordinated to the quinolyl carbon atoms of two ligands and the methine carbon of another ligand. The average K−C distance of 3.251 Å is slightly longer than those in [K{η5-C5H4(SiMe3)}]∞ (3.027 Å)26 and in [K{η5-C5H4R(DME)}]∞ (3.080 Å; R = (+)-neomenthyl),27 indicating that 2587

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Table 2. Selected Bond Distances (Å) and Angles (deg) for Compounds 9 and 10

Table 3. Selected Bond Distances (Å) and Angles (deg) for Compounds 11 and 12

[Ge{μ2-C(iPr2PS)(C9H6N-2)}]2 (9)

[Sn{μ2-C(iPr2PS)(C9H6N-2)}]2 (11)

Ge(1)−N(1) 2.042(5) Ge(2)−N(2) Ge(1)−C(10) 2.127(6) Ge(2)−C(10) Ge(1)−C(26) 2.097(6) Ge(2)−C(26) P(1)−S(1) 1.950(3) P(2)−S(2) P(1)−C(10) 1.776(6) P(2)−C(26) Ge(1)−C(10)−Ge(2) 87.1(2) C(10)−Ge(2)−C(26) Ge(1)−C(26)−Ge(2) 86.3(2) C(10)−P(1)−S(1) Ge(1)−N(1)−C(9) 94.0(4) C(26)−P(2)−S(2) Ge(1)−C(10)−C(9) 87.0(4) N(1)−Ge(1)−C(10) Ge(2)−N(2)−C(25) 95.6(4) N(2)−Ge(2)−C(26) Ge(2)−C(26)−C(25) 86.6(4) N(1)−C(9)−C(10) C(10)−Ge(1)−C(26) 92.8(2) N(2)−C(25)−C(26) [Pb{μ2-C(iPr2PS)(C9H6N-2)}]2 (10)

2.036(5) 2.102(6) 2.162(6) 1.966(3) 1.788(6) 91.6(2) 109.3(2) 115.6(2) 66.6(2) 66.0(2) 109.4(5) 109.9(5)

Sn(1)−N(1) 2.316(5) Sn(2)−N(2) Sn(1)−C(10) 2.337(7) Sn(2)−C(10) Sn(1)−C(26) 2.326(7) Sn(2)−C(26) P(1)−S(1) 1.991(3) P(2)−S(2) P(1)−C(10) 1.774(6) P(2)−C(26) Sn(1)−C(10)−Sn(2) 88.6(2) C(10)−Sn(2)−C(26) Sn(1)−C(26)−Sn(2) 88.9(2) C(10)−P(1)−S(1) Sn(1)−N(1)−C(1) 95.7(4) C(26)−P(2)−S(2) Sn(1)−C(10)−C(1) 92.3(4) N(1)−Sn(1)−C(10) Sn(2)−N(2)−C(17) 96.1(4) N(2)−Sn(2)−C(26) Sn(2)−C(26)−C(17) 91.4(4) N(1)−C(1)−C(10) C(10)−Sn(1)−C(26) 88.7(2) N(2)−C(17)−C(26) [Pb{μ2-C(iPr2PS)(C9H6N-2)}]2 (12)

2.298(6) 2.318(7) 2.317(7) 1.983(3) 1.753(7) 89.4(2) 105.9(2) 106.1(2) 58.9(2) 59.9(2) 110.4(5) 110.1(6)

Pb(1)−C(10) Pb(1)−C(26) Pb(1)−S(1) Pb(1)−S(2) P(1)−S(1) P(1)−C(10) Pb(1)−C(10)−Pb(2) Pb(1)−C(26)−Pb(2) Pb(1)−C(10)−P(1) Pb(1)−C(26)−P(2) Pb(1)−S(1)−P(1) Pb(1)−S(2)−P(2) Pb(2)−C(10)−C(9) Pb(2)−C(26)−C(25) Pb(2)−N(1)−C(9) Pb(2)−N(2)−C(25)

2.431(8) 2.385(8) 2.636(6) 2.651(6) 1.998(3) 1.753(9) 89.1(3) 90.1(3) 67.5(2) 64.3(2) 105.0(3) 106.9(3) 113.4(7) 115.1(7) 54.8(2) 55.6(2)

Pb(1)−N(1) Pb(1)−C(10) Pb(1)−C(26) Pb(1)−S(2) P(1)−S(1) P(1)−C(10) Pb(1)−C(10)−Pb(2) Pb(1)−C(26)−Pb(2) Pb(1)−N(1)−C(9) Pb(1)−C(10)−C(9) Pb(1)−S(2)−P(2) Pb(1)−C(26)−P(2) Pb(2)−N(2)−C(25) Pb(2)−C(26)−C(25) Pb(2)−S(1)−P(1) Pb(2)−C(10)−P(1)

2.463(5) 2.411(6) 2.422(6) 3.100(2) 1.995(3) 1.745(7) 88.6(2) 89.0(2) 64.6(2) 64.5(1) 105.8(2) 107.0(2) 114.1(5) 112.7(6) 57.0(2) 57.0(2)

2.443(9) 2.413(7) 2.900(2) 3.141(3) 2.021(3) 1.744(8) 88.6(3) 90.4(3) 98.8(3) 102.4(4) 79.3(9) 75.5(9) 95.4(5) 98.6(5) 90.0(4) 90.7(4)

Pb(2)−C(10) Pb(2)−C(26) Pb(2)−N(1) Pb(2)−N(2) P(2)−S(2) P(2)−C(26) C(10)−Pb(1)−C(26) C(10)−Pb(2)−C(26) C(10)−Pb(1)−S(1) C(26)−Pb(1)−S(2) C(10)−P(1)−S(1) C(26)−P(2)−S(2) N(1)−C(9)−C(10) N(2)−C(25)−C(26) N(1)−Pb(2)−C(10) N(2)−Pb(2)−C(26)

an aromatic π interaction between the anionic ligands and potassium ion is present. The K−N distance of 2.825 Å is comparable to that of 2.870 Å in [{{K{2-C5H4N(NSiMe3)}(12crown-4)}2}·2PhMe]28 and 2.787 Å in [{K{N(SiMe3)2}}2].29 It is noteworthy that the potassium atom is stabilized by a hard nitrogen atom and a soft sulfur atom as well as carbon atoms from the ligands without coordination to any solvent molecules. This is rarely found in the literature.30 Compound 9 consists of two germanium atoms bridged by two methanediide carbon atoms, forming a 1,3-Ge2C2 fourmembered ring (Figure 4). The two quinolyl nitrogen atoms of the ligand coordinate to the trigonal-pyramidal germanium atom to form GeCCN four-membered rings. These two GeCCN rings and the Ge2C2 group, as a base, form an “open-box” structure framework. The angle sum of the Ge2C2 ring of 357.8° indicates that the Ge2C2 ring is almost planar. The sum of angles at the two germanium centers are 255.5 and 251.0°, which is consistent with a stereoactive lone pair of electrons on each germanium center. The average Ge−N bond distance of 2.039 Å and the average Ge−C bond distance of 2.122 Å are comparable to those found in 1,3-[Ge{C(Pri2PNSiMe3)(2-Py)}]2 (Ge−N = 2.060 Å; Ge−C = 2.118 Å)19 and [{2-CH(iPr2PNSiMe3)-6-CH(iPr2P NSiMe3}C5H3NGe{2-{C(iPr2PNSiMe3)Ge}-6-CH2(iPr2P NSiMe3}C5H3N] (Ge−N = 2.044 Å; Ge−C = 2.093 Å).20 The average P−S bond distances of 1.958 Å in 9 is similar to that of 1.961 Å in neutral CH2(iPr2PS)(C9H6N-2). The Ge−Ge distance of 2.914 Å is too long to consider it as a bonding interaction. From the X-ray structure of compound 9, there is a 3.622 Å aromatic π-stacking interaction between two quinolyl

2.477(5) 2.422(6) 2.426(7) 3.071(2) 2.001(3) 1.761(6) 88.2(2) 87.9(2) 93.4(3) 93.5(4) 76.7(7) 103.3(3) 94.0(4) 93.2(4) 75.6(7) 100.9(3)

Pb(2)−N(2) Pb(2)−C(10) Pb(2)−C(26) Pb(2)−S(1) P(2)−S(2) P(2)−C(26) C(10)−Pb(1)−C(26) C(10)−Pb(2)−C(26) C(10)−Pb(2)−S(1) C(26)−Pb(1)−S(2) C(10)−P(1)−S(1) C(26)−P(2)−S(2) N(1)−C(9)−C(10) N(2)−C(25)−C(26) N(1)−Pb(1)−C(10) N(2)−Pb(2)−C(26)

Figure 1. Molecular structure of [Li(Et2O){CH(iPr2P−S)(C9H6N2)}]2 (4) (30% probability ellipsoids, hydrogen atoms omitted for clarity).

rings, which further stabilizes the “open-box” framework structure.25 Compound 10 consists of two lead atoms bridged by two methanediide carbon atoms, forming a 1,3-Pb2C2 four2588

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Figure 2. Molecular structure of [Mg{CH(iPr2P−S)(C9H6N-2)}2] (5) (30% probability ellipsoids, hydrogen atoms omitted for clarity).

Figure 5. Molecular structure of [Pb{μ2-C(iPr2PS)(C9H6N-2)}]2 (10) (30% probability ellipsoids, hydrogen atoms and toluene molecule omitted for clarity).

2.418 Å are comparable to those found in 1,3-[Pb{C(Pri2P NSiMe3)(2-Py)}]2 (Pb−N = 2.594 Å; Pb−C = 2.411 Å),19 1,3[μ2-Pb{C(Ph2PNSiMe3)2}]2 (Pb−N = 2.647 Å; Pb−C = 2.477 Å),17 and [{2-{Pb{C(Pri2PS)}}-6-{CH2(Pri2PS)}}C5H3N]2 (Pb−N = 2.547 Å; Pb−C = 2.423 Å).12 The Pb(1)− S(1) distance of 2.900(2) Å in 10 is shorter than or comparable to those found in [{2-{Pb{C(Pri2PS)}}-6-{CH2(Pri2P S)}}C5H3N]2 (3.050 Å)12 and [Pb{μ2-C(Ph2PS)2}]2 (2.906 Å),13 while the Pb(1)−S(2) distance of 3.141(3) Å is much longer than the reported value, suggesting that a bonding interaction between the Pb(1) and S(2) atoms is not present. The Pb−Pb distance of 3.405 Å is longer than the sum of covalent radii (3.08 Å) but is significantly shorter than the sum of van der Waals radii (4.04 Å), which indicates that a weak lead− lead interaction may be present in 10.31 Compound 11 consists of two tin atoms bridged by two methanediide carbon atoms, forming a 1,3-Sn2C2 fourmembered ring (Figure 6). The two quinolyl nitrogen atoms of the ligand coordinate to the trigonal-pyramidal tin atom to form SnCCN four-membered rings. These two SnCCN rings

Figure 3. Molecular structure of [K{CH(iPr2P−S)(C9H6N-2)}]n (6) (30% probability ellipsoids, hydrogen atoms omitted for clarity).

Figure 4. Molecular structure of [Ge{μ2-C(iPr2PS)(C9H6N-2)}]2 (9) (30% probability ellipsoids, hydrogen atoms omitted for clarity).

membered ring (Figure 5). The two quinolyl nitrogen atoms and the one thio sulfur atom of the ligand coordinate to the lead atom to form PbCCN and PbCPS four-membered rings. These two PbCCN rings, one PbCPS ring, and Pb2C2 form a “twisted-step” structural framework. The angle sum of the Pb2C2 ring of 358.2° indicates that the Pb2C2 ring is almost planar. The average Pb−N bond distance of 2.644 Å and the average Pb−C bond distance of

Figure 6. Molecular structure of [Sn{μ2-C(iPr2PS)(C9H6N-2)}]2 (11) (30% probability ellipsoids, hydrogen atoms omitted for clarity). 2589

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and the Sn2C2 form an “open-box” structure framework. The angle sum of the Sn2C2 ring of 355.6° indicates that the Sn2C2 ring is almost planar. The sums of angles at the two tin centers are 237.9 and 237.6°, which is consistent with a stereoactive lone pair of electrons on each tin center. The average Sn−N bond distance of 2.307 Å and the average Sn−C bond distance of 2.325 Å are comparable to those found in 1,3-[Sn{C(Pri2PNSiMe3)(2Py)}]2 (Sn−N = 2.470 Å; Sn−C = 2.325 Å),19 1,3-[μ2Sn{C(Ph2PNSiMe3)2}]2 (Sn−N = 2.462 Å; Sn−C = 2.376 Å), 17 and [{2-{Sn{C(Pr i 2 PS)}}-6-{CH 2 (Pr i 2 PS)}}C5H3N]2 (Sn−N = 2.400 Å; Sn−C = 2.308 Å).12 The average P−S bond distance of 1.987 Å in 11 is similar to that of 1.961 Å in neutral CH2(iPr2PS)(C9H6N-2). The Sn−Sn distance of 3.252 Å is too long to consider it as a bonding interaction. In addition, the average Sn−S bond distance of 3.612 Å is also too long to consider the presence of a dative bonding interaction. From the solid-state structure of compound 11, there a 3.285 Å is aromatic π-stacking interaction between the two quinolyl rings, which further stabilizes the “open-box” framework structure.25 Compound 12 consists of two lead atoms bridged by two methanediide carbon atoms, forming a 1,3-Pb2C2 fourmembered ring (Figure 7). The two quinolyl nitrogen atoms

which indicates that a weak lead−lead interaction may be present in 12.31 From the solid-state structure of compound 12, there is a 3.405 Å aromatic π-stacking interaction between two quinolyl rings.25

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CONCLUSION To summarize, the monoanionic lithium, magnesium, and potassium salts derived from 2-quinolyl-linked (thiophosphosphorano)methane have been synthesized and characterized. The monolithium salt can be used as a ligand transfer reagent to synthesize a series of low-valent group 14 1,3dimetallacyclobutanes. The structures of all compounds have been characterized by X-ray crystallography and NMR spectroscopy.

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EXPERIMENTAL SECTION

General Procedures. All manipulations were carried out under an inert atmosphere of dinitrogen gas by standard Schlenk techniques. Solvents were dried over and distilled from CaH2 (hexane) and/or Na (Et2O, toluene, and THF). Sn{N(SiMe3)2}2 and Pb{N(SiMe3)2}2 were prepared according to the literature procedures.32 2-Methylquinoline, chlorodiisopropylphosphine, sulfur, nBuLi (1.6 M in hexane), nBu2Mg (1.0 M in heptane), GeCl2·(dioxane), PbCl2, and KtBuO were purchased from Aldrich Chemical Co. and used without further purification. The 1H, 13C{1H}, 31P{1H}, 119Sn{1H}, and 207Pb{1H} spectra were recorded on a Bruker 400 spectrometer. The NMR spectra were recorded in CDCl3 and THF-d8, and the chemical shifts are relative to SiMe4 for 1H and 13C{1H} and to 85% H3PO4, SnMe4, and PbMe4 for 31 1 P{ H}, 119Sn{1H}, and 207Pb{1H}, respectively. Preparation of CH2(iPr2PS)(C9H6N-2) (3). To a mixture of 2methylquinoline (6.75 mL, 50.0 mmol), TMEDA (7.50 mL, 50.0 mmol), and Et2O (200 mL) was added dropwise nBuLi (34.5 mL, 55 mmol) at 0 °C. The mixture was stirred at room temperature for 6 h and was then added dropwise to a cooled (−90 °C) solution of iPr2PCl (7.95 mL, 50.0 mmol) in Et2O (30 mL). The mixture was stirred at −90 °C for 30 min and at room temperature for 18 h. The mixture was then filtered, and the volatiles were removed under reduced pressure. The crude product was purified as a yellow oil by distillation under reduced pressure (0.01 mmHg, bp 118 °C). A solution of 2 (10.74 g, 41.41 mmol) in THF (30 mL) was added slowly to a solution of sulfur (1.32 g, 41.41 mmol) in THF (10 mL) at room temperature. The solution was stirred at 60 °C for 6 h, and a yellow solution was obtained. The resultant solution was filtered and concentrated; compound 3 was obtained as colorless crystals. Yield: 10.04 g (83.2%) Mp: 135.5 °C. Anal. Found: C, 65.21; H, 7.62; N, 5.33. Calcd for C16H22NPS: C, 65.95; H, 7.61; N, 4.81. 1H NMR (CDCl3, 25 °C): δ 1.13−1.23 (m, 12H, CHMe2), 2.20− 2.33 (m, 2H, CHMe2), 3.63 (d, 1H, JP−H = 12 Hz, CH2), 7.49 (t, 1H, JH−H = 16 Hz, Qu), 7.67 (t, 1H, JH−H = 16 Hz, Qu), 7.78 (d, 1H, JH−H = 8 Hz, Qu), 7.97 (d, 1H, JH−H = 8 Hz, Qu), 8.08 (d, 1H, JH−H = 8 Hz, Qu). 13 C{1H} NMR (CDCl3, 25 °C): δ 16.3 (CHMe2), 27.9 (CHMe2), 38.6 (CH2), 123.1, 126.3, 127.0, 127.7, 128.7, 129.4, 135.8, 147.8, 154.3 (Qu). 31P{1H} NMR (CDCl3, 25 °C): δ 65.4. Preparation of [Li(Et2O){CH(iPr2P−S)(C9H6N)}]2 (4). To a solution of 3 (2.64 g, 9.06 mmol) in THF (50 mL) was added nBuLi (6.8 mL, 10.88 mmol) slowly at −90 °C. The colorless solution turned orange immediately. It was stirred at room temperature for 12 h, and a red solution was formed. All the volatiles in the reaction mixture were removed under reduced pressure, and the residue was extracted with Et2O (20 mL) and hexane (20 mL). After filtration and concentration of the filtrate, compound 4 was obtained as orange crystals. Yield: 2.26 (67.1%). Mp: 269.8 °C. Anal. Found: C, 64.16; H, 8.45; N, 4.25. Calcd for C40H62Li2N2O2P2S2: C, 64.67; H, 8.41; N, 3.77. 1H NMR (THF-d8, 25 °C): δ 1.13−1.21 (m, 12H, CHMe2), 1.98−2.11 (m, 2H, CHMe2), 3.04 (d, 1H, 2JP−H = 20 Hz, CH), 6.55 (d, 1H, JH−H = 16 Hz, Qu), 6.85 (t, 1H, JH−H = 12 Hz, Qu), 6.95 (d, 1H, JH−H = 8 Hz, Qu), 6.99 (m, 3H, Qu). 13C{1H} NMR (THF-d8, 25 °C): δ = 17.1 (CHMe2), 30.5 (CHMe2), 59.5 (CH), 117.1, 121.4, 123.1, 125.9, 127.2, 128.4, 131.2, 151.8, 166.2 (Qu). 31P{1H} NMR (THF-d8, 25 °C): δ 51.7.

Figure 7. Molecular structure of [Pb{μ2-C(iPr2PS)(C9H6N-2)}]2 (12) (30% probability ellipsoids, hydrogen atoms omitted for clarity).

and the one thio sulfur atom of the ligand coordinate to the lead atom to form PbCCN and PbCPS four-membered rings. These two PbCCN rings and Pb2C2 form an “open-box” structure framework. The angle sum of the Pb2C2 ring of 353.7° indicates that the Pb2C2 ring is almost planar. The average Pb−N bond distance of 2.470 Å and the average Pb−C bond distance of 2.420 Å are comparable to those found in 1,3-[Pb{C(Pri2P NSiMe3)(2-Py)}]2 (Pb−N = 2.594 Å; Pb−C = 2.411 Å),19 1,3-[μ2-Pb{C(Ph2PNSiMe3)2}]2 (Pb−N = 2.647 Å; Pb−C = 2.477 Å),17 and [{2-{Pb{C(Pri2PS)}}-6-{CH2(Pri2PS)}}C5H3N]2 (Pb−N = 2.547 Å; Pb−C = 2.423 Å).12 The Pb(1)− S(2) bond distance of 3.071(2) Å in 12 is comparable to those found in [Pb{μ2-C(Ph2PS)2}]2 (2.906 Å)13 and [{2-{Pb{C(Pri2PS)}}-6-{CH2(Pri2PS)}} C5H3N]2 (3.050 Å),12 while the Pb(2)−S(1) bond distance of 3.124(2) Å is slightly longer than the reported value, suggesting that a bonding interaction between the Pb(2) and S(1) atoms may be absent. The average P−S bond distance of 1.998 Å in 12 is similar to that of 1.961 Å in neutral CH2(iPr2PS)(C9H6N-2). The Pb−Pb distance of 3.355 Å is longer than the sum of covalent radii (3.08 Å) but is significantly shorter than the sum of van der Waals radii (4.04 Å), 2590

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Preparation of [Mg{CH(iPr2P−S)(C9H6N-2)}2] (5). To a solution of 3 (0.56 g, 1.92 mmol) in THF (30 mL) was added nBu2Mg (1.0 mL, 1.00 mmol) slowly at −90 °C. The colorless solution turned yellow immediately. It was stirred at room temperature for 12 h, and a orange solution was formed. All the volatiles in the reaction mixture were removed under reduced pressure, and the residue was extracted with hexane (20 mL). After filtration and concentration of the filtrate, compound 5 was obtained as yellow crystals. Yield: 0.40 g (68.8%). Mp: 157.8 °C. Anal. Found: C, 62.95; H, 7.32; N, 4.76. Calcd for C32H42MgN2P2S2: C, 63.52; H, 7.00; N, 4.63. 1H NMR (THF-d8, 25 °C): δ 1.19−1.26 (m, 12H, CHMe2), 2.12−2.23 (m, 2H, CHMe2), 3.21 (d, 1H, 2JP−H = 16 Hz, CH), 6.25 (d, 1H, JH−H = 8 Hz, Qu), 6.64 (t, 1H, JH−H = 16 Hz, Qu), 6.77 (d, 1H, JH−H = 8 Hz, Qu), 6.96 (t, 2H, JH−H = 20 Hz, Qu), 7.66 (d, 1H, JH−H = 8 Hz, Qu). 13C{1H} NMR (THF-d8, 25 °C): δ 16.5 (CHMe2), δ 30.6 (CHMe2), 57.9 (CH), 119.6, 121.7, 123.3, 126.8, 127.3, 128.8, 132.2, 148.5, 166.8 (Qu). 31P{1H} NMR (THF-d8, 25 °C): δ 51.0. Preparation of [K{CH(iPr2P−S)(C9H6N-2)}]n (6). A solution of t K BuO (0.78 g, 6.95 mmol) in THF (20 mL) was added to a solution of 4 (2.17 g, 2.92 mmol) in THF (10 mL) at 0 °C. The reaction mixture was stirred at room temperature for 12 h, and an orange solution was formed. All the volatiles in the reaction mixture were removed under reduced pressure, and the residue was extracted with Et2O (20 mL). After filtration and concentration of the filtrate, compound 6 was isolated as orange crystals. Yield: 1.85 g (96.2%) Mp: 229.1 °C. Anal. Found: C, 58.06; H, 5.64; N, 4.41. Calcd for C16H21KNPS: C, 58.33; H, 6.42; N, 4.25. 1H NMR (THF-d8, 25 °C): δ 1.15−1.24 (m, 12H, CHMe2), 2.33−2.47 (m, 2H, CHMe2), 3.04 (d, 1H, 2JP−H = 20 Hz, CH), 6.28 (d, 1H, JH−H = 8 Hz, Qu), 6.47 (t, 1H, JH−H = 16 Hz, Qu), 6.84 (t, 1H, JH−H = 20 Hz, Qu), 6.97 (q, 2H, JH−H = 20 Hz, Qu), 7.12 (d, 1H, JH−H = 16 Hz, Qu), 7.99 (d, 1H, JH−H = 8 Hz, Qu). 13C NMR (THF-d8, 25 °C): δ 18.0 (CHMe2), 29.5 (CHMe2), 61.1 (CH), 116.3, 122.4, 123.3, 124.3, 127.4, 128.6, 131.1, 152.4, 164.8 (Qu). 31P{1H} NMR (THF-d8, 25 °C): δ 53.5. Preparation of [Ge{μ2-C(iPr2PS)(C9H6N-2)}]2 (9). A solution of GeCl2·(dioxane) (0.15 g, 0.65 mmol) in THF (10 mL) was added to a solution of 4 (0.48 g, 0.65 mmol) in THF (20 mL) at −90 °C. The reaction mixture turned orange, and it was stirred at room temperature for 1 day. A orange solution was formed. All the volatiles in the reaction mixture were removed under reduced pressure, and the residue was extracted with Et2O (20 mL) and CH2Cl2 (10 mL). After filtration and concentration of the filtrate, compound 9 was isolated as orange crystals. Yield: 0.33 g (70.8%). Mp: 144.7 °C. Anal. Found: C, 49.51; H, 5.41; N, 4.00. Calcd for C32H40Ge2N2P2S2·CH2Cl2: C, 49.00; H, 5.23; N, 3.46. 1 H NMR (THF-d8, 25 °C): δ 0.94−0.99 (m, 6H, CHMe2), 1.19−1.31 (m, 18H, CHMe2), 2.54−2.62 (m, 1H, CHMe2), 2.76−2.85 (m, 1H, CHMe2), 2.88−2.91 (m, 1H, CHMe2), 2.93−3.01 (m, 1H, CHMe2), 7.27 (t, 4H, JH−H = 8 Hz, Qu), 7.40 (d, 2H, JH−H = 8 Hz, Qu), 7.50 (d, 2H, JH−H = 8 Hz, Qu), 7.58 (d, 1H, JH−H = 12 Hz, Qu), 7.82 (d, 1H, JH−H = 12 Hz, Qu), 8.29 (d, 1H, JH−H = 8 Hz, Qu), 8.89 (d, 1H, JH−H = 8 Hz, Qu). 13C{1H} NMR (THF-d8, 25 °C): δ 18.4 (CHMe2), 32.1 (CHMe2), 118.0, 122.5, 124.1, 126.6, 129.9, 134.2, 138.0, 149.8, 164.0 (Qu). 31 1 P{ H} NMR (THF-d8, 25 °C): δ 69.5. Preparation of [Pb{μ2-C(iPr2PS)(C9H6N-2)}]2 (10). A solution of PbCl2 (0.42 g, 1.51 mmol) in THF (10 mL) was added to a solution of 4 (1.12 g, 1.51 mmol) in THF (20 mL) at −90 °C. The reaction mixture turned orange, and it was stirred at room temperature for 1 day. A orange solution was formed. All the volatiles in the reaction mixture were removed under reduced pressure, and the residue was extracted with toluene (20 mL). After filtration and concentration of the filtrate, compound 10 was isolated as red crystals. Yield: 0.68 g (45.0%). Mp: 201.2 °C. Anal. Found: C, 39.41; H, 4.17; N, 3.26. Calcd for C32H40N2P2Pb2S2: C, 38.70; H, 4.06; N, 2.82. 1H NMR (THF-d8, 25 °C): δ 1.22−1.42 (m, 24H, CHMe2), 2.44−2.58 (m, 4H, CHMe2), 6.61 (t, 2H, JH−H = 12 Hz, Qu), 6.68 (d, 1H, JH−H = 8 Hz, Qu), 6.73 (d, 1H, JH−H = 8 Hz, Qu), 7.07 (t, 2H, JH−H = 8 Hz, Qu), 7.12 (t, 3H, JH−H = 12 Hz, Qu), 7.18 (d, 1H, JH−H = 8 Hz, Qu), 7.84 (d, 1H, JH−H = 8 Hz, Qu), 8.13 (d, 1H, JH−H = 8 Hz, Qu). 13C{1H} NMR (THF-d8, 25 °C): δ 18.3 (CHMe2), 32.6 (CHMe2), 61.7 (PbCPb), δ 124.7, 126.9, 128.0, 128.3, 129.2, 134.1, 148.4, 161.2, 162.7 (Qu). 31P{1H} NMR (THF-d8, 25 °C):

δ 57.6 (2J31P−207Pb = 68.0 Hz), 59.8 (2J31P−207Pb = 63.2 Hz). 207Pb{1H} NMR (THF-d8, 25 °C): δ 2189 (ν1/2 = 507 Hz), 2647 (ν1/2 = 507 Hz). Preparation of [Sn{μ2-C(iPr2PS)(C9H6N)}]2 (11). A solution of Sn{N(SiMe3)2}2 (0.74 g, 1.68 mmol) in toluene (10 mL) was added to a solution of 3 (0.45 g, 1.54 mmol) in toluene (20 mL) at room temperature. The reaction mixture turned orange, and it was stirred at room temperature for 2 days. A turbid orange mixture was formed. All the volatiles in the reaction mixture were removed under reduced pressure, and the residue was extracted with Et2O (20 mL). After filtration and concentration of the filtrate, compound 12 was isolated as red crystals. Yield: 0.27 g (42.9%) Mp: 275.5 °C. Anal. Found: C, 46.64; H, 5.09; N, 3.64. Calcd for C32H40N2P2S2Sn2: C, 47.10; H, 4.95; N, 3.43. 1 H NMR (THF-d8, 25 °C): δ 1.32−1.39 (m, 24H, CHMe2), 2.50−2.59 (m, 4H, CHMe2), 6.78 (t, 2H, JH−H = 16.0 Hz, Qu), 6.89 (d, 2H, JH−H = 8.0 Hz, Qu), 6.97 (d, 2H, JH−H = 8.0 Hz, Qu), 7.06 (d, 2H, JH−H = 8.0 Hz, Qu), 7.11 (t, 2H, JH−H = 20.0 Hz, Qu), 7.45 (d, 2H, JH−H = 12.0 Hz, Qu). 13 C{1H} NMR (THF-d8, 25 °C): δ 18.1 (CHMe2), 32.9 (CHMe2), 121.5, 122.7, 123.8, 127.7, 129.5, 131.4, 137.9, 144.7, 165.6 (Qu). 31 1 P{ H} NMR (THF-d8, 25 °C): δ 61.8 (2J31P−119Sn = 45.4 Hz). 119Sn{1H} NMR (THF-d8, 25 °C): δ −12.0 (2J119Sn−31P = 92.5 Hz). Preparation of [Pb{μ2-C(iPr2PS)(C9H6N)}]2 (12). A solution of Pb{N(SiMe3)2}2 (0.68 g, 1.28 mmol) in toluene (10 mL) was added to a solution of 3 (0.35 g, 1.20 mmol) in toluene (20 mL) at room temperature. The reaction mixture turned yellow, and it was stirred at room temperature for 2 days. A turbid red mixture was formed. All the volatiles in the reaction mixture were removed under reduced pressure, and the residue was extracted with Et2O (20 mL). After filtration and concentration of the filtrate, compound 13 was isolated as red crystals. Yield: 0.30 g (50.0%) Mp: 203.2 °C. Anal. Found: C, 38.57; H, 4.20; N, 2.99. Calcd for C32H40N2P2Pb2S2: C, 38.70; H, 4.06; N, 2.82. 1H NMR (THF-d8, 25 °C): δ 1.28−1.41 (m, 24H, CHMe2), 2.44−2.69 (m, 4H, CHMe2), 6.58 (t, 1H, JH−H = 12 Hz, Qu), 6.62 (d, 1H, JH−H = 8 Hz, Qu), 6.67 (d, 1H, JH−H = 8 Hz, Qu), 6.73 (d, 1H, JH−H = 8 Hz, Qu), 6.99 (t, 1H, JH−H = 12 Hz, Qu), 7.05 (t, 2H, JH−H = 16 Hz, Qu), 7.14 (d, 1H, JH−H = 8 Hz, Qu), 7.64 (t, 2H, JH−H = 16 Hz, Qu), 7.68 (d, 1H, JH−H = 8 Hz, Qu), 7.73 (d, 1H, JH−H = 8 Hz, Qu), 7.93 (d, 1H, JH−H = 8 Hz, Qu).13C{1H} NMR (THF-d8, 25 °C): δ 18.2 (CHMe2), 32.6 (CHMe2), 61.9 (PbCPb), 123.5, 124.2, 125.3, 125.8, 126.9, 127.6, 128.3, 128.5, 129.1, 134.1, 135.5, 136.1, 143.8, 162.8, 163.5 (Qu). 31P{1H} NMR (THF-d8, 25 °C): δ 58.7 (2J31P‑207Pb = 66.4 Hz), 60.9 (2J31P‑207Pb = 61.6 Hz). 207 Pb{1H} NMR (THF-d8, 25 °C): δ 2644 (ν1/2 = 152 Hz), 2646 (ν1/2 = 152 Hz). X-ray Crystallography. Single crystals were sealed in Lindemann glass capillaries under nitrogen. X-ray data of 2−8 were collected on a Rigaku R-AXIS II imaging plate using graphite-monochromatized Mo Kα radiation (λ = 0.71073 Ǻ ) from a rotating-anode generator operating at 50 kV and 90 mA. Crystal data are summarized in Tables 4 and 5 (Supporting Information). The structures were solved by direct phase determinations using the computer program SHELXTL-PC33 on a PC 486 and refined by full-matrix least squares with anisotropic thermal parameters for the non-hydrogen atoms. Hydrogen atoms were introduced in their idealized positions and included in structure factor calculations with assigned isotropic temperature factor calculations. Full details of the crystallographic analysis of 3−6 and 9−12 are given in the Supporting Information.

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ASSOCIATED CONTENT

S Supporting Information *

Tables, figures, and CIF files giving details about the X-ray crystal structures, including ORTEP diagrams and tables of crystal data and structure refinement, atomic coordinates, bond lengths and angles, and anisotropic displacement parameters for 3−6 and 9− 12, and selected 31P, 119Sn, and 207Pb NMR spectra for 10−12. This material is available free of charge via the Internet at http:// pubs.acs.org. 2591

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(18) Leung, W.-P.; Wan, C.-L.; Mak, T. C. W. Organometallics 2010, 29, 1622. (19) Leung, W.-P.; Wang, Z.-X.; Li, H.-W.; Yang, Q.-C.; Mak, T. C. W. J. Am. Chem. Soc. 2001, 123, 8123. (20) Leung, W.-P.; Ip, Q. W.-Y.; Wong, S.-Y.; Mak, T. C. W. Organometallics 2003, 22, 4604. (21) Leung, W.-P.; Wong, K.-W.; Wang, Z.-X.; Mak, T. C. W. Organometallics 2006, 25, 2037. (22) Orzechowski, L.; Jansen, G.; Harder, S. J. Am. Chem. Soc. 2006, 128, 14676. (23) Bjernemose, J. K.; Davies, R. P.; Jurd, A. P. S.; Martinelli, M. G.; Raithby, P. R.; White, A. J. P. Dalton Trans. 2004, 3169. (24) Armstrong, A.; Chivers, T.; Tuononen, H. M.; Parvez, M. Inorg. Chem. 2005, 44, 5778. (25) Hunter, C. A.; Sanders, J. K. M. J. Am. Chem. Soc. 1990, 112, 5525. (26) Jutzi, P.; Leffers, W.; Hampel, B.; Pohl, S.; Saak, W. Angew. Chem., Int. Ed. Engl. 1987, 26, 583. (27) Leung, W.-P.; Song, F.-Q.; Xue, F.; Mak, T. C. W. J. Chem. Soc., Dalton Trans. 1997, 4307. (28) Liddle, S. T.; Clegg, W. J. Chem. Soc., Dalton Trans. 2001, 402. (29) Tesh, K. F.; Hanusa, T. P.; Huffman, J. C. Inorg. Chem. 1990, 29, 1584. (30) (a) Clark, D. L.; Gordon, J. C.; Huffman, J. C.; Vincent-Hollis, R. L.; Watkin, J. G.; Zwick, B. D. Inorg. Chem. 1994, 33, 5903. (b) Yang, Y.F.; Foo, C.; Ganguly, R.; Li, Y.; So, C.-W. Organometallics 2012, 31, 6538. (c) Murugesapandian, B.; Kuzdrowska, M.; Gamer, M. T; Hartenstein, L.; Roesky, P. W. Organometallics 2013, 32, 1500. (31) Haynes, W. H. CRC Handbook of Chemistry and Physics, 93rd ed.; Taylor and Francis Group: London, 2012. (32) Gynane, M. J. S.; Harris, D. H.; Lappert, M. F.; Power, P. P.; Rivière, P.; Rivière-Baudet, M. J. Chem. Soc., Dalton Trans. 1977, 2004. (33) Sheldrick, G. M. In Crystallographic Computing 3: Data Collection, Structure Determination, Proteins, and Databases; Sheldrick, G. M., Kruger, C., Goddard, R., Eds.; Oxford University Press: New York, 1985; p 175.

AUTHOR INFORMATION

Corresponding Author

*E-mail for W.-P.L.: [email protected]. Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS This work was supported by The Chinese University of Hong Kong Direct Grant (CUHK2009).

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REFERENCES

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dx.doi.org/10.1021/om400062e | Organometallics 2013, 32, 2584−2592