Synthesis and Structure of the First Terminal Borylene Complexes

A nearly linear arrangement is observed for the three atoms in the central W-B-N unit of the tungsten complex [(CO)₅WBN(SiMe₃)₂] ( 1 ) in the crystal (W-B-N 177.9°; see picture). This compound along with its Cr analogue represent the first examples of terminal borylene complexes with a two-coordinate metal-bound boron atom. The geometries of the axial and equatorial CO groups in 1 are similar, and thus indicate that there is no trans effect of the borylene ligand.