Iminophosphide Bonding Environments from Carbene Complexes of Iminophosphines Neil Burford,* T. Stanley Cameron, Daren J. LeBlanc, and Andrew D. Phillips Department of Chemistry, Dalhousie UniVersity Halifax, NoVa Scotia B3H 4J3, Canada Thomas E. Concolino, Kin-Chung Lam, and Arnold L. Rheingold Department of Chemistry, UniVersity of Delaware Newark, Delaware 19716 ReceiVed February 4, 2000 Stable compounds containing multiple bonding environments highlight important new directions in the diversification of phosphorus chemistry. While numerous examples of compounds containing 1, 2, and 3 have been identified, 1 other environments such as 4 have proven elusive. Salts of anions assigned as iminophosphides 4b 2 (also referred to as iminophosphoranides) 3 have solid-state structures best described as the corresponding phosphinoamides 4a, 4 the relative stability of which has been theoretically modeled. 5 We have now exploited the coordination chemistry of unsaturated phosphorus(III) to prepare neutral systems represented by 4c, involving a pyramidal tricoordinate phosphorus center with a lone pair and a distinctive NdP double bond. The new complexes involve the now routinely available carbenes, 6 which engage in substantially stronger donor-acceptor interactions with phosphorus 6c than those observed with amines, 7,8 arenes, 9 or phosphines. 7,10 31 P NMR spectroscopic studies of reaction mixtures containing equimolar amounts of imidazol-2-ylidene (carb, 5) with Mes*NPCl 6a (136 ppm) or Mes*NPOSO 2 CF 3 6b (50 ppm) (Mes* ) 2,4,6- tri-tert-butylphenyl) show almost quantitative (>85%) formation of the corresponding adducts 7a (156 ppm) and 7b (350 ppm), respectively. The complexes have been isolated and comprehen- sively characterized, 11a,b and their structures are shown in Figure 1. Structural parameters are presented in Table 1, in comparison with those of the closely related complexes 7c ( 31 P NMR 71 ppm) 11c and 7d, 10c as well as lithium phosphinoamide derivatives. 4 The N-P bond lengths for derivatives of 7 are in the range observed for iminophosphine and iminophosphorane derivatives (1.46-1.62 Å), 1d,14 and are substantially shorter than those observed for derivatives of phosphinoamides (1.66-1.67 Å). 4 The (1) For example: (a) Dillon, K. B.; Mathey, F.; Nixon, J. F. Phosphorus: The Carbon Copy; From Organophosphorus to Phospha-organic Chemistry; John Wiley and Sons: New York, 1998. Multiple Bonds and Low Coordination in Phosphorus Chemistry; Regitz, M., Scherer, O. J., Eds.; Georg Thieme Verlag: New York, 1990. (b) Cowley, A, H.; Kemp, R. A. Chem. ReV. 1985, 85, 367-382. (c) Niecke, E.; Gudat, D. Angew. Chem., Int. Ed. Engl. 1991, 30, 217-237. (d) Power, P. Chem. ReV. 1999, 99, 3463-3503. (e) Loss, S.; Widauer, C.; Gru ¨tzmacher, H. Angew. Chem., Int. Ed. Engl. 1999, 38, 3329- 3331. (f) Igau, A.; Baceiredo, A.; Gru ¨tzmacher, H.; Pritzkow, H.; Bertrand, G. J. Am. Chem. Soc. 1989, 111, 6853-6854. (2) Romanenko, V. D.; Ruban, A. V.; Markovski, L. N. J. Chem. Soc., Chem. Commun. 1983, 187-189. (3) Cowley, A. H.; Kemp, R. A. J. Chem. Soc., Chem. Commun. 1982, 319-320. (4) (a) Poetschke, N.; Nieger, M.; Khan, M. A.; Niecke, E.; Ashby, M. T. Inorg. Chem. 1997, 36, 4087-4093. (b) Ashby, M. T.; Li, Z. Inorg. Chem. 1992, 31, 1321-1322. (5) Trinquier, G.; Ashby, M. T. Inorg. Chem. 1994, 33, 1306-1313. (6) See, for example: (a) Arduengo, A. J. Acc. Chem. Res. 1999, 32, 913- 921. (b) Bourissou, D.; Guerret, O.; Gabbaı ¨, F. P.; Bertrand, G. Chem. ReV. 2000, 100, 31-91. (c) Carmalt, C. J.; Cowley, A. H. AdV. Inorg. Chem. 2000, 50,1-32. (7) Jones, V. A.; Sriprang, S.; Thornton-Pett, M.; Kee, T. P. J. Organomet. Chem. 1998, 567, 199-218. (8) (a) Payrastre, C.; Madaule, Y.; Wolf, J. G.; Kim, T. C.; Mazie `res, M.- R.; Wolf, R.; Sanchez, M. Heteroat. Chem. 1992, 3, 157-162. (b) Bouhadir, G.; Reed, R. W.; Re ´au, R.; Bertrand, G. Heteroat. Chem. 1995, 6, 371-375. (c) Burford, N.; Losier, P.; Bakshi, P. K.; Cameron, T. S. J. Chem. Soc., Chem. Commun. 1996, 307-308; (9) Burford, N.; Clyburne, J. A. C.; Bakshi, P. K.; Cameron, T. S. Organometallics 1995, 14, 1578-1585. (10) (a) David, G.; Niecke, E.; Nieger, M.; Radseck, J. J. Am. Chem. Soc. 1994, 116, 2191-2192. (b) Romanenko, V. D.; Rudzevich, V. L.; Rusanov, E. B.; Chernega, A. N.; Senio, A.; Sotiropoulos, J.-M.; Pfister-Guillouzo, G.; Sanchez, M. J. Chem. Soc., Chem. Commun. 1995, 1383-1385. (c) Burford, N.; Cameron, T. S.; Clyburne, J. A. C.; Eichele, K.; Robertson, K. N.; Sereda, S.; Wasylishen, R. E.; Whitla, W. A. Inorg. Chem. 1996, 35, 5460-5467. (d) Burford, N.; Cameron, T. S.; LeBlanc, D. J.; Losier, P.; Sereda, S.; Wu, G. Organometallics 1997, 16, 4712-4717. (e) Burford, N.; LeBlanc, D. J. Inorg. Chem. 1999, 38, 2248-2249. (11) Preparative procedures for derivatives of 7: A benzene solution of the neutral ligand was slowly added to a stirred benzene solution of 6. After 1 h, the solvent was removed in vacuo giving crystalline material, which was washed with benzene. Samples for X-ray diffraction studies were recrystallized by slow diffusion of hexane into a saturated benzene solution (7a and 7b) or by slow evaporation of a 1:1 CH2Cl2/hexane solution (7c). (a) 7a:5, 0.16 g, 0.89 mmol; 6a, 0.30 g, 0.92 mmol; orange crystals, 0.11 g, 0.22 mmol, 25%; mp 177-178 °C dec. Anal. Calcd: C, 68.82; H, 9.76; N, 8.30. Found: C, 69.08; H, 9.82; N, 8.36. IR (cm -1 , rel intensity): 1623m, 1596w, 1415s, 1392s, 1384s, 1361s, 1351m, 1319w, 1286m, 1260s, 1250s, 1240s, 1188m, 1172m, 1138m, 1123m, 1115m, 1084m, 1020m, 977w, 952w, 936w, 922w, 906m, 888w, 877m, 824w, 793m, 783w, 774m, 756m, 708w, 692m, 674w, 656w, 643w, 551w, 514w, 496w, 400m, 363w. 1 H and 13 C NMR details are consistent with other derivatives of Mes*NP and 7: 31 P NMR (CD2Cl2) 172 ppm ( 1 JPC ) 115 Hz); crystal data, C29H49ClN3P, M ) 506.13, monoclinic, P21/c, a ) 21.8062(3) Å, b ) 8.5184(1) Å, c ) 17.8511(2) Å,  ) 110.892(1)°, V ) 3097.90(7) Å 3 , T ) 213(2) K, Z ) 4, µ(Mo KR) ) 0.195 mm -1 , 9422 measured reflections, 4217 independent reflections, 3497 reflections with I > 2σ(I), 307 refined parameters, R[F 2 > 2σ(F 2 )] ) 0.085, wR(F 2 ) ) 0.2753, S ) 1.082. (b) 7b:5, 0.12 g, 0.67 mmol; 6b, 0.31 g, 0.70 mmol; purple crystals; 0.16 g, 0.26 mmol, 38%; mp 149-151 °C dec. Anal. Calcd: C, 58.14; H, 7.97; N, 6.78. Found: C, 58.20; H, 7.82; N, 6.85. IR (cm -1 , rel. intensity): 1611w, 1596w, 1418m, 1280s, 1246s, 1229s, 1221s, 1159m, 1122s, 1090w, 1026m, 909w, 877w, 795m, 754w, 693w, 549w, 517m, 499w, 452w, 400w, 346w. 1 H and 13 C NMR details are consistent with other derivatives of Mes*NP and 7; 31 P NMR (CD2Cl2) 339 ppm ( 1 JPC ) 132 Hz); 19 F NMR (CD2Cl2) -78.6 ppm ( 1 JFC ) 321 Hz); crystal data, C30H49F3N3O3PS, M ) 619.75, orthorhombic, Pbca, a ) 10.6688(2) Å, b ) 15.2337(3) Å, c ) 42.5078(6) Å, V ) 6908.6(2) Å 3 , T ) 213(2) K, Z ) 8, µ(Mo KR) ) 0.189 mm -1 , 23185 measured reflections, 5361 independent reflections, 3752 reflections with I > 2σ(I), 370 refined parameters, R[F 2 > 2σ(F 2 )] ) 0.0892, wR(F 2 ) ) 0.1699, S ) 1.215. (c) 7c:pyridine complexes of iminophosphines have been previously mentioned [Bla ¨ttner, M.; Ruban, A.; Gudat, D.; Nieger, M.; Niecke, E. Phosphorus, Sulfur Silicon 1999, 147, 31]. Pyridine, 0.13 g, 1.64 mmol; 6b, 0.30 g, 0.69 mmol; orange-red crystals,0.11 g, 0.22 mmol, 31%; mp 118- 120 °C. Anal. Calcd: C, 55.59; H, 6.61; N, 5.40. Found: C, 55.04; H, 6.95; N, 5.42. IR (cm -1 , rel. intensity): 1611w, 1597w, 1540w, 1496m, 1481m, 1397w, 1367m, 1362m, 1288s, 1265m, 1234s, 1211w, 1167m, 1161m, 1060m, 1024s, 1008m, 887w, 880w, 771m, 758w, 692w, 651w, 638s, 520w, 429w, 379w. 1 H and 13 C NMR details are consistent with other derivatives of Mes*NP and pyridine: 31 P NMR (CD2Cl2) 71 ppm; 19 F NMR (CD2Cl2) -78.9 ppm ( 1 JFC ) 320 Hz); crystal data, C24H34F3N2O3PS, M ) 518.56, triclinic, P1 h, a ) 10.298(3) Å, b ) 16.842(4) Å, c ) 8.835(2) Å, R) 95.69(2)°,  ) 112.24- (2)°, γ ) 80.66(2)°, V ) 1398.4(6) Å 3 , T ) 296(2) K, Z ) 2, µ(Cu KR) ) 19.72 cm -1 , 3143 measured reflections, 2932 independent reflections, 1354 reflections with I > 3σ(I), 228 refined parameters, R ) 0.057, Rw ) 0.060, S ) 1.95. 5413 J. Am. Chem. Soc. 2000, 122, 5413-5414 10.1021/ja000432+ CCC: $19.00 © 2000 American Chemical Society Published on Web 05/20/2000