Volume 26 Number 7 April 8, 1987
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Inorganic Chemistry 0 Copyright 1987 by the American Chemical Society
Communications N-H Activation. 1. Oxidative Addition of Ammonia to Iridium(1). Isolation, Structural Characterization, and Reactivity of Amidoiridium Hydrides Sir: Although the oxidative addition of N-H bonds may be an important step in the selective functionalization of ammonia, amines, and other N-H-containing molecules, examples of this reaction with nonactivated molecules are scarce. Reaction of NH3 with the early-transition-metal complexes CpTiC5H4TiCp2and CpzMH2 ( M = Zr, Hf)may involve N-H oxidative and M3(CO)12 ( M = Os, Ru) oxidatively adds ammonia and simple amines! Molecules containing more activated N-H bonds such as amides, imides, and ammonium ions undergo N-H addition reactions to other group VI11 (group &loz4) c ~ m p l e x e s . ~ In our study of the reactivity of amines and ammonia with transition-metal complexes, we chose to emphasize the late metals over the early metals. The weaker, late-metal M-N bond should be more reactive and enhance the potential for catalysis. We report here the first example of the oxidative addition of ammonia to a mononuclear late-transition-metal complex, including isolation, structural characterization, and reactivity of the product hydrido-amido complexes. We have employed in our studies an electron-rich, low-valent, sterically unhindered iridium complex that contains labile ethylene of a THF solution ligands, I T ( P E ~ ~ ) ~ ( C ~(1).6 H ~ ) ~Reaction CI of 1 with an excess of liquid ammonia at 25 "C over 24 h gave C2H4and the iridium hydride complex 2 (Scheme I) as a white powder in ca. 90% isolated yield. Although solution N M R spectra of 2 could not be obtained due to its high insolubility,' the formulation of 2 is supported by solid-state 31PMAS N M R (s, -8.4 ppm), IR (uIr-H = 2162 cm-' (s); uN-H = 3355 (m), 3313 (m), (1) (2) (3) (4)
Armor, J. N. Inorg. Chem. 1978, 17, 203. Armor, J. N. Inorg. Chem. 1978, 17, 213. Hillhouse, G. L.; Bercaw, J. E. J. Am. Chem. SOC.1984, 106, 5472. (a) Suss-Fink, G. Z. Nuturforsch., B Anorg. Chem., Org. Chem. 1980, 3 5 4 454. (b) Sappa E.; Milone, L. J . Organomet. Chem. 1973,61, 383. (c) Lin, Y.; Mayr, A,; Knobler, C. B.;Kaesz, H. D. J. Orgunomet. Chem. 1984, 272, 207. (d) Johnson, B. F. G.; Lewis, J.; Odiaka, T.; Raithby, P. R. J. Orgunomet. Chem. 1981,216, C56. ( e ) Johnson, B. F. G.; Lewis, J. J. Chem. SOC.,Dalton Trans. 1977, 1328. (5) (a) Hadden, D.: Roundhill, D. M.; Fultz, W. C.; Rheingold, A. L. J. Am. Chem. SOC.1984,106,5014. (b) Roundhill, D. M. Inorg. Chem. 1970, 9,254-258. (c) Yamamoto, T.; Sano, K.; Yamamoto, A. Chem. Lett. 1982,907-910. (d) Nelson, J. H.; Schmidt, D. L.; Henry, R. A,; Moore, D. W.; Jonassen, H. B. Inorg. Chem. 1970,9, 2678-2681. (e) Fornies, J.; Green, M.; Spencer, J. L.; Stone, F. G. A. J . Chem. SOC., Dalton Trans. 1977, 1006-1009. (0 Goel, R. A.; Srivastava, R. C. J. Organomet. Chem. 1983, 244, 303-310. (9) Rauchfuss, T. B.; Roundhill, D. M. J. Am. Chem. SOC.1974,96,3098-3105. (g) Mague, J. T. Inorg. Chem. 1972, 11, 2558-2560. (6) Tulip, T., unpublished results. The compound was synthesized from [Ir(~yclooctene),Cl]~, PEt,, and C2H4. (7) 2, was found to be soluble in CH,OH; however, an unambiguous assignment of its NMR spectra in CD30D was precluded by the rapid formation of other Ir species. NH2, NH,, and (Ir-H resonances were observed, however, in the 'H NMR spectrum.
I
4
ii
iv
L
L
I
5
38-c
I
Jv L
L
6a,b
7a,b
"Reaction conditions: (i) NH,(I), 25 OC,24 h; (ii) NaBPh4, AgBF, or TIPF, in acetone (3a, X = BPh4; 3b, X = BF,; 312, X = PF,); (iii) 110 OC,pyridine; (iv) TIPF,, acetone; (v) L, acetone (623, L = CO (50 psi); 6b,L = t-BuNC); (vi) TIPF, + L in acetone.
3217 (s), 31 15 cm-I (s); Nujol) and elemental analyses as well as by the compositions and structures of the related derivatives 3 and 4 (vide infra). Treatment of 2 with 1 eq of NaBPh4 in methanol followed by crystallization of the resulting white solid from acetone/diethyl ether (solvent/vapor diffusion) gave rectangular pale yellow crystals of 3a in about 50% isolated yield. The BF4- and PF6salts could be obtained in a similar fashion by treatment with AgBF, or TlPF,, respectively. Complex 4 was obtained by heating a stirred slurry of 2 in pyridine at 110 OC for about 1 h. The resulting yellow solution, which contained 4 quantitatively by NMR, was filtered, stripped in vacuo to a yellow precipitate, which was redissolved in toluene, and filtered again. Crystallization from toluene by vapor diffusion of pentane gave colorless, irregular block-shaped crystals of 4 in about 50% isolated yield.* Since no other crystallographically characterized M(NH2)(H) complexes had been previously reported? complexes 3a and 4 were ~
~
(8) By removing the toluene in vacuo, 4 was obtained as a slightly impure solid in ca. 90% yield. This material was of sufficient purity for the syntheses of the derivatives 6a,b and 7a,b. (9) Several M(NH2)(NH,) complexes have been structurally characterized. (a) Kretschmer, M.; Heck, L. Z . Anorg. Allg. Chem. 1982, 490, 215. (b) Schaefer, W. P. Acta Crystallogr.,Sect. C Cryst. Struct. Commun. 1983, 39, 1610. (c) Rotzwinger, F. P.; Marty, W. Inorg. Chem. 1983, 22, 3593. (d) Clegg, W.; Sykes, A. G. Acta Crysrallogr., Sect. C Cryst. Struct. Commun.1984, 40, 1820. (e) Curtis, N. J.; Hagen, K. S.; Sargeson, A. M. J. Chem. Soc., Chem. Commun.1984, 1571.
0020-1669/87/1326-0971~01.50/0 0 1987 American Chemical Society
972 inorganic Chemistry, Vol. 26, No. 7, 1987
K'
Communications
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Figure 1.
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4 showing thermal ellipsoids at 20% probability level. Selected bond distances (A) and angles (deg) are as follows. For 313: Ir-Nl, 2.244 (4); Ir,-N2, 2.128 (3); Irl-N2, 2.127 (3); Irl-Hl, 1.61 ( 5 ) ; Irl-Pl, 2.274 (1); Irl-P2, 2.280 (1); N2-Irl-N2, 77.0 (1); N,-Irl-N2, 84.3 (1); N1-IrI-N2, 84.5 (1); PIIrl-N2, 170.1 (1); P2-Ir,-N,, 169.9 (1); Hl-Irl-Nl, 157 (2). For 4: Irl-Nl, 2.10 (1); Irl-Nl, 2.13 (1); Irl-Pl, 2.264 (4); Irl-P2, 2.264 (4); Irl
