MULTIPLY BONDED DIMETAL FLUOROALKOXIDES .1. PENTAFLUOROPHENOXIDES OF DIMOLYBDENUM AND DITUNGSTEN

A series of dimolybdenum and ditungsten pentafluorophenoxides has been prepared by alcoholysis of M2(NMe2)6 (M = Mo, W) with pentafluorophenol. Mo2(OC6F5)4(NMe2)2(NHMe2)2 has been isolated both from the reaction of Mo2(NMe2)6 with 6 equiv of pentafluorophenol (1a) and as a disproportionation product with 2 equiv of pentafluorophenol (1b). The crystals are different but contain molecules with essentially identical structural features. Eight equivalents of pentafluorophenol react with Mo2(NMe2)6 in benzene to yield Mo2(OC6F5)5(NMe2)(NHMe2)2•2C6H6 (2). From reactions with 10 or 12 equiv of pentafluorophenol, only low yields of Mo2(OC6F5)4(NHMe2)4 (3) and [(NH2Me2)2][Mo2O2(μ-O)2(OC6F5)4] (4) have been isolated, both of which are structurally characterized. W2(OC6F5)6(NHMe2)2 (5) has been prepared from the reaction of 10 equiv of pentafluorophenol with W2(NMe2)6 and structurally characterized. Crystallographic parameters of these five alkoxides are as follows. Mo2(OC6F5)4-(NMe2)2(NHMe2)2 (1a): space group C2/c, a = 21.511 (5) Å, b = 9.057 (2) Å, c = 20.581 (3) Å, β = 103.88 (1)°, V= 3892 (1) Å3, Z = 4. 1b: space group Pbcn, a = 24.177 (4) Å, b = 10.927 (3) Å, c = 14.475 (3) Å, V = 3824 (1) Å3, Z = 4. Mo2(OC6F5)5(NMe2)(NHMe2)2•2C6H6 (2) space group ####, a = 11.785 (3) Å, b = 20.062 (4) Å, c = 11.686 (2) Å, α = 93.14 (2)°, β = 91.39 (2)°, γ = 73.80 (2)°, V= 2649 (1) Å3, Z = 2. MoZ2(OC6F5)4(NHMe2)4 (3): space group C2/c, a = 19.799 (8) Å, b = 8.995 (7) Å, c = 22.248 (6) Å, β = 96.54 (3)°, V = 3937 (1) Å3, Z = 4. [(NH2Me2)2] [MO2O2(μO)2(OC6F5)4)] (4): space group C2/c, a = 13.233 (2) Å, b = 11.276 (3) Å, c = 25.178 (4) Å, β = 102.82 (1)°, V = 3663 (1) A3, Z = 4. W2(OC6F5)6(NHMe2)2 (5): space group C2/c, a = 10.766 (4) Å,b = 22.020 (7) Å, c = 19.463 (5) Å, β = 96.78 (2)°, V= 4582 (3) Å3, Z = 4. © 1990, American Chemical Society. All rights reserved.