The dicarbonyl(eta (3)-allyl)molybdenum and tri-carbonyliodotungsten comple
xes with hydrotris(methimazolyl)borate (Tm) are reported as the first examp
les of transition-metal organometallic complexes of the Tm ligand, serving
as general entry points for a wide range of group 6 organometallic complexe
s. Their crystal structures have been determined, and comparisons are made
with the homologous pyrazolylborate (Tp) and cyclopentadienyl (Cp) complexe
s, leading to predictions regarding their reactions.