0 Copyright 1995 American Chemical Society
Volume 14, Number 10, October 1995
Communications Formation of the Metal-CoordinatedChelating Bis-Phosphorus Ligand PhaPN(Et)C(O)PPhavia a Novel [3 21 Cycloaddition between the Phosphenium Complexes Cp(CO)(HPh2P)M=PPh2(M = Mo, W)and Ethyl Isocyanate1
+
Wolfgang Malisch" and Helmut Pfister Institut fur Anorganische Chemie der Universitat Wurzburg, Am Hubland, 0-97074Wurzburg, Germany
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Received May 23, 1995@
Summary: Convenient access to the unusual hydrido complexes Cp(CO)(H)MPPhzC(O)N(Et)PPhz(M = Mo (4a,a'), W (4b,b')),obtained as mixtures of two isomers, is established via cycloaddition between the phosphenium complexes Cp(CO)(HPhzP)M=PPhz (2a,b) and EtNCO (3). Reaction of 4a,b with carbon tetrachloride yields the analogous chloro complexes Cp(CO)(Cl)-
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MPPhzC(O)N(Et)PPhz (5a,a', 5b,b');5 b has been characterized by X-ray analysis. In keeping with our studies concerning the reactivity of the secondary phosphine substituted phosphenium complexes Cp(CO)(HPhzP)M=PPhz (M = MQ (2a), W (2b)),characterized by a stereogenic metal center, we have described the chemo- and regioselective [2 21 cycloaddition with isothiocyanates.2 In analogy to the reactions of the basic system Cp(CO)zM=PPhz (M = Mo, WI3 the cycloadducts contain the four-membered-ring
+
skeleton M -P-C -S . In this communication we present the reaction of these phosphenium complexes with ethyl isocyanate (31, which dramatically deviates from the known pattern. @Abstractpublished in Advance ACS Abstracts, August 15, 1995. (1)Phosphenium Transition Metal Complexes. 36. Part 35: Gunzelmann, N.; Fey, 0.;Malisch, W. J . Organomet. Chem., submitted for publication. (2) Pfister, H.; Malisch, W. J. Organomet. Chem. 1992, 439, C11.
It yields five-membered diphosphametallacycles via a novel type of [3 21 cycloaddition between the central P-M-P bonding system of 2a,b and the C=N bond of ethyl isocyanate (3). Addition of 3 to a freshly prepared solution of the phosphenium complexes 2a,b2in toluene, generated by dehydrochlorination of Cp(CO)(HPhzP)2MCl(la,b)with 1,8-diazabicyclo[5.4.Olundec-7-ene (DBU), causes a slow change of the color from green (2a)or blue (2b)to brown. After a reaction period of 1 (4a) or 4 days (4b) the hydrido complexes 4a,b are obtained after chromatographic purification as pale yellow microcrystalline powders, showing moderate solubility in aromatic sol4a,b can be described as the product v e n t ~ .Complexes ~ of a formal [3 21 cycloaddition, accompanied by a shift of the P-bonded hydrogen t o the metal (Scheme 1). Addition of ethyl isocyanate (3)occurs chemoselectively at the C=N double bond, creating a new kind of PNCP-chelating ligand, which to our knowledge has so far not been accessible in the free state. The NMR spectra reveal the existence of mixtures of two diaster-
+
+
(3)(a) Fried, A.; Malisch, W.; Schmeusser, M.; Weis, U. Phosphorus, Sulfur Silicon Relat. Elem. 1992, 65, 75. (b) Malisch, W.; Hirth, U.A.; Fried, A.; Pfister, H. Phosphorus, Sulfur Silicon Relat. Elem. 1993, 77, 17. (c) Sporl, A.; Hindahl, K.; Fried, A,; Pfister, H.; Malisch, W. In Selective Reactions of Metal-Activated Molecules, Werner, H., Griesbeck, A. G., Adam, W., Bringmann, G., Kiefer, W., Eds.; Vieweg: Braunschweig, Germany, 1992; p 191. (d) Fried, A.; Hahner, C.; Malisch, W. In ref IC, p 195.
0 1995 American Chemical Society Q276-7333/95/2314-4443$Q9.QQ/Q
Communications
4444 Organometallics, Vol. 14, No. 10, 1995
The structure of 4a,a' and 4b,b follows especially from the lH NMR spectra,l exhibiting two M-H resonances at approximately -8.0 ppm, with a coupling constant 2 J p of~ about 75 (4a,b)or 60 Hz (4a',b)to the cis-positioned phosphorus and of 20 Hz (maximum) to the trans-positioned p h o s p h ~ r u s . ~Further ,~ evidence is given by the off-resonance-decoupled31PNMR spectra, showing a splitting of the P(N) signal in the main diastereomer 4a,b or the P(C) signal in the minor diastereomer 4a',b, due to coupling with the cis hydrido ligand. A reasonable explanation for the unexpected behavior of the phosphenium complexes 2a,b is based on an equilibrium between 2 and its tautomer A, which is the M hydrogen shift (Scheme 2). A is result of a P characterized by two electronically different phosphorus atoms, one of the phosphido (nucleophilic) and one of the phosphenium type (electrophilic), suggesting 1,3dipolar behavior. Although A is not observable in solution even at -60 "C by NMR spectroscopy, indicating extremely low concentration in the equilibrium (Scheme 21, support
Scheme 1 /Ph
+
EtN=C=O (3)
1
-
4a; b'
4a, b +
CC14
1
-CHCIj
181.07(d, 1Jpc = 53.9Hz, C(O)),140.76-126.64(C6H5),85.38(5, C5H5), 41.49(dd, VPNC = 3.8Hz, 3 J p C N C = 3.8Hz, CHz), 10.46ppm (s, CH3); 31P NMR (162.0MHz/[Dslbenzene) 6 110.91(d, ' V p w p = 61.2Hz, lJwp = 319.4Hz, PN), 61.21ppm (d, V p w p = 61.2Hz, lJwp = 268.2Hz, PC); IR (toluene) v 1853 (vs, CO), 1651 (m, C(0)) cm-'. Anal. Calcd for C33H31NOPzW (719.41):C, 55.10;H, 4.31;N, 1.95.Found: C, Sa, b Sa', b' 55.30;H, 4.15;N, 1.71,[1,2-Bis(diphenylphosphino~-l-ethyl-2-oxo1-azaethane-P,F"] (carbonyl)chloro(q6-cyclopentadienyl)molybdenum(I1) (5da'):mp 96 "C dec. Diastereomeric ratio: 3:2. Main eomers 4a,a' (ratio 5 2 ) and 4b,b (ratio 2:1),indicating diastereomer (5a):'H NMR (400.1MHz/CDC13) d 8.03-7.01(m, 20 H, H5C6), 4.30(d, 3 J p ~ o = c ~2.2Hz, 5 H, H5C& 3.83 (dqd, 'JHCH = that both modes of the C-N bond addition t o the two 13.4Hz, 3 J ~ c=c 6.7 ~ HZ, 3 J ~=~6.7 cHz, ~ 1 H, HzC), 3.02(dqd, 'JHCH phosphorus atoms have been realized, leading to a = 13.4HZ, 3JHCCH = 6.7HZ, 3 J P N C H = 6.7HZ, 1 H, HzC),0.14ppm (t, product with the hydrido ligand in a position cis either 3 J ~ c=c 6.7 ~ Hz, 3 H, H3C); 13C NMR (100.6MHdCDC13) 6 248.04(d, 'JPM,C = 24.1Hz, OCMO),180.86(dd, 'Jpc = 43.1Hz, 'JPNC = 28.1 t o the nitrogen or to the carbon-bonded phosphorus. Hz, C(O)), 141.00-127.27(CsHj), 94.89(s,C5H51, 42.57(dd, 'JPNC = 4.0Hz, 3 J p c ~ c= 4.0Hz, CH'), 11.67ppm (s, CH3); 31P NMR (162.0 MHz/CDC13) 6 115.91(d, 'JPMQ = 76.7Hz, PN), 88.14ppm (d, zJp.uop (4)Experimental details are given in the supporting information. = 76.6Hz, PC); IR (toluene) Y 1892 (vs, CO), 1647 (m, C(0)) cm-'. Analytical and spectroscopic data are as follows. [l,a-Bis(diphenMinor diastereomer (5a'):'H NMR (400.1MHdCDClQ)6 8.03-7.01 ylphosphino~-l-ethyl-2-oxo-l-azaethane-P~lc~bonyl(q~-cyclopentadienyl)hydridomolybdenum(II) (4a,a'): mp 202 "C dec. Diastereomeric ratio: 5:2(determined as for the following compounds by integration of the H5C5 NMR signal). Main diastereomer (4a):lH 'JHCH = 13.5HZ, 3JHCCH = 6.7HZ, 3JPNCH = 4.1Hz, 1 H, HzC), -0.08 ppm (t, 3 J H c c H = 6.7Hz, 3 H, H3C); 13C NMR (100.6MHdCDC13) 6 NMR (400.1MHz/[Dslbenzene) 6 8.50-6.91(m, 20 H, H&s), 4.36(s, 251.24(d, ' J p ~ ~=c27.2Hz, OCMO),181.37(dd, 'Jpc = 43.0Hz, 'JPNC 5H, H&d, 3.68(m, 1H, HzC), 3.02(m, 1 H, HzC), 0.25(m, 3 H, H&), = 25.7 Hz, C(O)), 141.00-127.27(CsHs), 95.89(s, C5H51, 42.78(dd, -8.10 ppm (dd, 2 J p . ~ o=~ 80.1Hz, 2 J p b m o H = 19.2Hz, 1 H, HMO)(Nbonded uhosuhorus marked a s Pa and C-bonded as Pb): l3C NMR (100.6 2 J 3.7 ~ Hz, ~3JPCNC ~ = 3.7Hz, CHz), 11.14ppm (s,CH3); 31P NMR (162.0MHzlCDC13) 6 144.35(d, 'JPM,,~ = 91.7Hz, PN), 63.42ppm (d, MHz/[Di]be&ene) 6 237.27(br, OCMo), 185.55(br,' C(O)), 141.00'Jp~,,p = 91.7Hz, PC); IR (toluene) Y 1892 (vs, CO), 1647 (m, C(0)) 126.00(CsH6),86.89(s, C5H5),40.98(s, CHz), 10.93ppm (s, CH3); 31P C, 59.52;H, 4.54; cm-'. Anal. Calcd for C ~ ~ H ~ & I M O N O(665.95): ZPZ NMR (162.0MHz/[Ds]benzene): b 131.53(d, 2 J ~ ~ = , p77.1Hz, PN). N, 2.10.Found: C, 59.04;H, 4.54; N, 1.76.[1,2-Bis(diphenylphos87.06ppm (d, 2 J p ~ =~ 77.1 p Hz, PC): IR (toluene) Y 1864(vs, CO), 1644 phino)-l-ethyl-2-oxo-l-azaethane-P,F"l~carbonyl~chloro(~S-cy. (m, C(0)) cm-'. Minor diastereomer (4a'): 'H NMR (400.1MHz/[Dslclopentadienyl)tungsten(II) (5b,b):mp 106 "C dec. Diastereomeric 3.57(m. 1 benzene) 6 8.50-6.91(m. 20 H. H&). 4.29(s. 5 H. HKCS.). ratio: 1:l. Diastereomer 5b: 'H NMR (400.1MHdCDC13) 6 8.05H, HzC), 3.02(m, 1 H, H'C), 0.26(m;3 H, H3C), -8.15 ppm (d, br, 7.15(m, 20 H, H&6), 4.39(d, 3 J P W C H = 2.4Hz, 5 H, H&), 3.88(dqd, 'JpbMoH = 60.0Hz, 1 H, HMO); 31P NMR (162.0MHflDslbenzene) 6 141.54(d, V p ~ , , p = 79.5Hz, PN), 90.35ppm (d, z J p ~ o p= 79.5Hz, PC); 'JHCH = 13.5HZ, 3JHCCH = 6.7HZ, 3 J P N C H = 6.7HZ, 1 H, HzC), 3.24 (dqdd, 'JHCH = 13.4HZ, 3 J ~ c=c 6.7 ~ HZ, 3 J p ~ =c 6.7 ~ HZ, ' J p c p ~ c= ~ IR (toluene) v 1864 (vs, CO), 1644 (m,-C(O)) cm-l. Anal. Calcd for 2.7Hz, 1 H, HzC), 0.16ppm (t, 3 J ~ c =c 6.7 ~ Hz, 3 H, H3C); 13C NMR N, 2.22.Found: C, 62.54; C33H31M~NOP2(631.5):C, 62.76;H, 4.95; H, 5.12;N, 2.08. [1,2-Bis(diphenylphosphino)-l-ethyl-2-oxo-l- (100.6MHz/CDC13) d 237.35(d, ' J p c w = 17.3Hz, OCW), 183.06-181.02 a z a e t h a n e - P ~ l c a r b o n y l ( ~ ~ - ~ c l o p e n t a d i e n y l ~ h y ~ d o t (C(O)), ~ g ~ ~ n141.00-126.93 (CsH.51, 91.57(S, C5H5), 41.58(s, CHz), 10.23 (11) (4b,b): mp 210 "C dec. Diastereomeric ratio: 2:l. Main ppm (s, CH3); 31P NMR (162.0MHz/CDC13) 6 90.17(d, V p w p = 48.9 Hz, lJwp = 313.1Hz, PN),56.42ppm (d, V p w p = 48.9Hz, l J w p = 254.3 diastereomer (4b):'H NMR (400.1MHz/[Dslbenzene) 6 8.05-6.90(m, Hz, PC); IR (CHC13) Y 1881(vs, CO), 1652(s, C(0)) cm-I. Diastereomer 20 H, H&s), 4.32(S,5 H, H5C5), 3.67(dqd, VHCH = 13.2Hz, 3 J ~ c c=~ 7.0Hz, 3 J p ~=c 6 ~.6Hz, 1 H, Hp2),3.14(dqd, 'JHCH = 13.2Hz, 3 J ~ c c ~ 5b: 'H NMR (400.1MHz/CDC13) 6 8.05-7.15(m, 20 H, H&), 4.46 (d, 3 J p w c ~= 2.1Hz, 5 H, H5C51, 3.56(dqd, 'JHCH = 13.8Hz, 3 J ~ c = c~ = 6.9HZ, 3 J P N C H = 3.3HZ, 1 H, HzC), 0.18(t, 3JHCCH = 6.9HZ, 3 H, H&), -7.80ppm (dd, VP~WH = -72.9Hz, V p b w = 18.5Hz, 1 H, HW); 6.7Hz, 3 J ~ =~6.9cHz, ~ 1 H, HzC), 2.89(dqdd, 'JHCH = 13.5Hz, 3 J ~ c c ~ = 12.85Hz, 13C NMR (100.6MHz/[Dslbenzene) 6 228.23 (d, VPWC = 6.7HZ, 3 J P N C H = 6.5HZ, 'JpCpNCH = 2.1HZ, 1 H, HzC), -0.07 ppm (t, 3 J ~ c =c 6.7 ~ Hz, 3 H, H3C); 13CNMR (100.6MHz/CDC13) 6 240.99 OCW), 180.76(d, 'Jpc = 53.9Hz, C(O)), 140.76-126.64(CsH51, 84.90 (s, C5H5), 40.90(dd, *JPNC = 4.2Hz, 3 J p c ~ = c 4.2Hz, CHz), 10.91ppm (d, 'Jpcw = 19.8Hz, OCW), 183.06-181.02(C(O)), 141.00-126.93 ( C & , ) , 92.61(s, C5H5), 41.98(s, CHZ),10.71ppm (s, CH3); 31P NMR (s, CH3); 31P NMR (162.0MHz/[Delbenzene) 6 100.43(d, %Jpwp = 56.4 (400.1MHdCDC13) 6 110.42(d, z J p w p = 62.7Hz, 'Jwp = 276.6 Hz, Hz, 'Jwp = 283.1Hz, PN), 59.64ppm (d, U p w p = 56.4Hz, V w p = 297.8 PN), 38.66ppm (d, V p w p = 62.7Hz, lJwp = 280.8Hz, PC); IR (CHCl3) Hz, PC); IR (toluene) Y 1853 (vs, CO), 1651 (m, C(0)) cm-'. Minor diastereomer (4b):'H NMR (400.1MHz/[Delbenzene) 6 8.05-6.90(m, Y 1881 (vs, CO), 1652 (s, C(0)) cm-'. Anal. Calcd for C ~ ~ H ~ O N O P Z W 20 H, H5C6), 4.18(6, 5H, H5C51, 3.42(dqd, 'JHCH = 13.3Hz, 3 J ~ c =c ~ (753.86):C, 52.58;H, 4.01; N, 1.86.Found: C, 52.70; H, 4.40;N, 1.29. (5) At, H. G.; Engelhardt, H. E.; Klaui, W.; Muller, A. J . Organomet. 6.9HZ, 3 J ~ =~ 6.7 c HZ, ~ 1 H, HzC), 3.05(dqd, 'JHCH = 13.3Hz, 3 J ~ c c ~ = 6.9HZ, 3JPNCH = 2.7HZ, 1 H, HzC), 0.09(t, 3JHCCH = 6.9HZ, 3 H, Chem. 1987,331, 317. H3C), -8.00ppm (dd, ' J p b w = 58.2Hz, V p * w = ~ 12.6Hz, 1 H, HW); (6)Baker, R. T.;Calabrese, J. C.; Harlow, R. L.; Williams, I. D. = 15.2Hz, OCW), 13C NMR (100.6 MHdDslbenzene) 6 230.77(d, VPWC Organometallics 1993,12, 812. I
1
I~
Organometallics, Vol. 14, No. 10, 1995 4445
Communications
Scheme 2
A
2
for its intermediate existence is given by Baker’s results for the related system (q6-Me5C5XMe3PXH)W=PPh~, where a type A tautomer has been identified by NMR spectroscopy and X-ray analysis.6 Treatment of the hydrido complexes 4a,a’ and 4b,b with carbon tetrachloride in dichloromethane at room temperature leads to quantitative WC1 exchange a t the metal to give the analogous chloro complexes (Scheme 1)in a diastereomeric ratio of 3:2 (5a,a’)or 1 : l (5b,b).4 The complexes 5, obtained as orange to red microcrystalline powders, show nearly the same spectroscopic data as 4, suggesting analogous structures. In the case of 5b,b’ slow evaporation of a benzene solution yields crystals of pure 5 b (chlorine cis to C-bourid phosphorus) suitable for X-ray analysis. The result confirms the proposed bis-phosphorus chelate structure, presumably also valid for the original cycloadducts 47 (Figure 1). The tungsten atom exhibits pseudo-square-monopyramidal coordination geometry with the cyclopentadienyl ligand in the apical position. The two phosphorus atoms adopt a cis arrangement at the metal with a n P-W-P angle of 76.39(8)” and define together with the CN unit of the former ethyl isocyanate the 1-metalla2,5-diphospha-3-azapentane cycle. The phenyl groups above the tetragonal base are aligned synperiplanar toward the cyclopentadienyl ring. The chelate system Pl-Nl-C2-P2 shows planarity with a torsion angle of 2.4(11)”. The length of the endocyclic carbonnitrogen bond of 1.346(12)A is significantly shorter than the C-N a-bond distance,* found for exocyclic Nl-C8 (1.494(11) A). This fact, together with the planarity of the nitrogen atom (sum of angles 358.9”), indicates a significant ninteraction between N1 and C2. Further investigations will deal with analogous reac(7)Crystallo aphic data for 5b: hexagonal, P66 (No. 1701,Z= 6, a = 23.708(4) b = 23.708(5)A, c = 10.113(6)A, V = 4923(3)A3, eealed = 1.528g ~ m - ~ Enraf-Nonius . CAD4 diffractometer, Mo KO. radiation (A = 0.7093 3407 independent reflections with 3” 28 52”collected, 3085 reflections used in refinement with I > 2dZ);R = 0.027,R, = 0.084.In the detected space group P65 (No. 170)the single molecules are arranged in a helical structure. As a result of the symmetrical properties of this space group and the chirality of the molecule, every crystal contains only one definite enantiomer. Because of the lower R value of the structure determination in space group P65 (No. 170)in comparison to that for the mirror symmetric space group P61 (No. 169),5a will be described in the first group.
A),
Figure 1. Crystal structure of Sb. Selected bond lengths (A): W1-P1 = 2.410(2), W1-P2 = 2.420(3), W1-CI1 = 2.506(3), W1-C1 = 1.943(11),P1-N1 = 1.737(8), P2-C2 = 1.892(7),02-C2 = 1.190(8),N1-C2 = 1.362(8),N1-C8 = 1.476(9),C8-C9 = 1.48(1). Selected bond angles (deg): Pl-Wl-P2 = 76.41(6), W1-P1-N1 = 113.8(2),N1-P1C l l O = 102.6(3), Wl-P2-C2 = 111.6(2), Pl-Nl-CP = 119.5(4), P1-Nl-CS = 123.9(5), P2-C2-N1 = 113.661, 02-C2-N1 = 123.8(6),Nl-C8-C9 = 114.8(8). Selected dihedral angles (deg): PB-Wl-Pl-Nl= 19.77(0.41),P1Wl-P2-C2 = -17.92(0.43), Wl-Pl-Nl-CB = -18.82(1.03), Wl-P2-C2-N1 = 14.33(1.01),P1-N1-C2-P1 = 2.58(1.24), C2-Nl-C8-C9 = 96.84(1.49). Hydrogen atoms have been omitted for clarity. tions of P-H-functionalized phosphenium complexes of the type Cp(CO)[H(Ph)(R)PlM=P(Ph)R(M = Mo, W; R = alkyl), with different organic substituents attached to the phosphorus, in order to realize stereocontrolled coupling of the two P(Ph)(R)moieties by isocyanates and other polar double-bond systems.
Acknowledgment. Generous support of these studies by the Deutsche Forschungsgemeinschaft (SFB 347: “Selektive Reaktionen Metall-aktivierter Molekule”) and the Fonds der Chemischen Industrie is gratefully acknowledged. Supporting InformationAvailable: Text giving experimental procedures and spectroscopic data for 4a,a’, 4b,b, 5a,a’,and 5b,b’and tables giving crystal data and refinement parameters, positional and thermal parameters, and bond distances and angles for 5b’ (11pages). Ordering information is given on any current masthead page.
OM950379B (8) (a) Hafelinger, G. Chem. Ber. €970,103, 2902. (b) Pauling, L. Die Natur der chemischen Bindung; Verlag Chemie: Weinheim, Germany, 1964.
