Dibromotetracarbonylmolybdenum, Mo(CO)4Br2,
and the dihalotetracarbonyltungsten compounds, W(CO)4X2
(where X = Cl, Br), have been isolated and characterized. These highly reactive
compounds are all diamagnetic. The trihalotetracarbonyl
anions [M(CO)4X3]- (M = Mo, W) have been isolated as
their tetraethylammonium salts from the parent halocarbonyls.
These yellow diamagnetic compounds are the first tetracarbonyl
derivatives to be prepared from the parent halocarbonyls.