Diazoalkane complexes of tungsten. Crystal structures of [WBr(N–NCHCH2CH2CH2OH)(dppe)2][PF6]·0.5EtOH (1) and [WBr(N–NCMe2)(dppe)2]Br·0.5MeOH (2)

Abstract

The X-ray crystal-structure determinations of the title complexes are described. Crystals of (1) are monoclinic, space group P2₁/n, with unit-cell dimensions a= 17.43 (1), b= 17.28(1), c= 19.00 (1)Å, β= 100.85(2)°, and Z = 4, and the structure has been refined to R= 0.064 based on 4 168 counter reflections. Crystals of (2) are monoclinic, space group P2₁/c, with a= 11.745(2), b= 22.638(2), c= 21.029(3)Å, β= 111.2(2)°, and Z= 4, and the structure has been refined to R= 0.060 based on 6 402 counter reflections. Complex (1) was previously thought to be [WBr([graphic omitted]H₂)(dppe)₂][PF₆][dppe = 1,2-bis(diphenylphosphino)ethane]. Unusual n.m.r parameters and difficulties in the preparation of diazoalkane complexes where both groups are larger than methyl are explained.