Ambidentate ligand with high p-acceptor capacity: D6-metal complexes of 4,4'-bipyrimidine. Angewandte Chemie, (97)5:431--433, 1985. [PUMA: Group VIB bipyridine bipyrimidine bipyrimidine;bipyrimidine bipyrimidine;chromium bipyrimidine;tungsten carbonyl carbonyl;molybdenum carbonyl;redox electrochem metal ruthenium ruthenium;carbonyl transition]