Preparation and properties of 1-adamantoxides, 2-adamantoxides, and 1-adamantylmethoxides of TiIV, VIV, NbIV, NbV, CrIII, CrIV, MoIV, MnII, FeIII, and CoII. The crystal and molecular structure of tetrakis(1-adamantoxo)dimethylaminemolybdenum(IV)

Abstract

By reaction of transition-metal dialkylamides with 1-adamantanol, 2-adamantanol, and 1-adamantylmethanol, a series of first- and second-row transition-metal alkoxides has been prepared. The complexes of tetra- and pentavalent metals are monomeric (those of M^II and M^III being polymeric) mostly crystalline solids. The air-stable tetrakis(1-adamantoxo)chromium(IV) is a convenient starting material for the preparation of chromium tetra-alkyls. An X-ray crystallographic study of Mo(1-ado)₄(NHMe₂)(1-ado = 1-adamantoxo) confirms a trigonal-bipyramidal structure of the complex, with the amine and one alkoxo-ligand in the axial positions. The axial Mo–O distance [1.963(2)Å] is ca. 0.06 Å longer than the equatorial distances [1.888(3)–1.916(2)Å], and Mo–N is 2.321(3)Å. The compound crystallises in the triclinic space group P, with a= 13.500(1), b= 13.168(2), c= 11.646(1)Å, α= 91.034(10), β= 103.835(8), γ= 70.842(10)°, and Z= 2. The structure has been solved by Patterson and Fourier methods and refined by least squares to R= 0.041 using 5 267 observed diffractometer data.