Chromium(0) complexes of sterically hindered vic-diamines

Abstract

[Dimethylamino(phenyl)carbene]pentacarbonylchromium, (CO)₅CrC(Ph)NMe₂, decomposes at 135° C in nitrogen to yield cis-(PhCH.NMe₂)₂Cr(CO)₄. Attempted preparations of (PhCH.NMe₂)₂by methylation of meso-stilbenediamine were unsuccessful. The mode of formation of (PhCH·NMe₂)₂ from the heterocarbenoid precursor is discussed.

Related complexes of the type cis-(vic-diamine)Cr(CO)₄, in which the vic-diamine is Me₂N·CHR¹·CHR²·NMe₂(R¹= R²= H; R¹= Me, R²= H; R¹= R²= Me), o-C₆H₄(NMe₂)₂, or (RCH.NH₂)₂(R = Me, Ph) are reported and the importance of steric effects in these complexes has been assessed by spectroscopic methods, Pure NNN′N′-tetramethyl-meso-butane-2,3-diamine has been fully characterised.