Mixed alkoxide-anilide d3-d3 dimers of molybdenum and tungsten. The X-ray crystal structures of M2(OBut)4(HNPh)2(H2NPh)2 (M = Mo, W)
摘要:
The reactions in diethyl-ether/hexane solutions between aniline and M2(OBut)6 (M = Mo, W) produce M2(OBut)4(HNPh)2(H2NPh)2 in high yield (79-85%) as red-black crystals. The compounds are air-sensitive, soluble in aromatic hydrocarbon solvents, and exhibit dynamic NMR behaviour. The IR spectra show nu(N-H) at 3320 and 3100 cm-1, corresponding to aniline and anilide N-H stretches, respectively. The X-ray crystal structures of M2(OBut)4(HNPh)2(H2NPh)2 are isomorphous for molybdenum and tungsten and reveal eclipsed four-coordinate, essentially planar ends supporting a metal-metal triple bond. Some important bond lengths and angles for W2(OBut)4(HNPh)2(H2NPh)2 (Mo2(OBut)4(NHPh)2(NH2Ph)2 in parentheses) are as follows (at - 169-degrees-C and - 168-degrees-C): M-M 2.3225(8) [2.2538(7)], M-O = 1.93 (1.94) (ave), 1.98 (1.96) (ave), M-N (amide) 1.97 (ave) [1.99 (ave)], M-N (amine) 2.37 angstrom (ave) [2.36 angstrom (ave)].