The chemistry of cyclopentadienyl and related nitrosyl complexes of molybdenum. Part V. Dihalogenonitrosyl[tris(pyrazolyl)borato]molybdenum complexes, their alcoholysis, and the crystal structure of chloronitrosylisopropoxo[tris(4-chloro-3,5-dimethylpyrazolyl)borato]molybdenum

Abstract

Halogenation of [Mo{HB(3,5-R₂C₃HN₂)₃}(NO)(CO)₂] gives [{Mo[HB(3,5-R₂-4-XC₃N₂)3](NO)Y₂}_n](R = X = H, Y = Cl, Br, or I, n= 2; R = Me, X = H, Y = Cl, Br, or I; n= 1; R = Me, X = Cl or Br, Y = Cl or Br, n= 1). These halides react with alcohols affording [Mo{HB(3,5-R₂-4-XC₃N₂)₃}(NO)Y(OR′)](R′= Me, Et, Prⁱ, Bu⁸, or CH₂CH:CH₂), the ¹H and ¹³C n.m.r. spectra of which are discussed. The crystal structure of [Mo{HB(3,5-Me₂-4-ClC₃N₂)₃}(NO)Cl(OPrⁱ)] has been determined by X-ray diffraction methods using counter data and refined by block-diagonal least-squares procedures, to R 0.047 for 2 450 reflections. The monoclinic unit-cell, space-group P2₁/n, has dimensions a= 12.268(4), b= 16.041(4), c= 15.033(5)Å, β= 91.44(4)° for Z= 4. The molybdenum atom has octahedral co-ordiantion and both the Mo–Cl and, particularly, the Mo–O distances are short. The Mo–O bond length (1.86 Å) indicates significant MoOR bonding and p_π→d_π donation from the alkoxy-group to the metal is discussed in terms of the apparent co-ordinative unsaturation of the alkoxide complexes.