Mono- and binuclear tri- and tetracarbonyl complexes of chromium(0), molybdenum(0), and tungsten(0) with the 2,2'-bipyrimidine radical anion. Inorganic Chemistry, (23)21:3365--3368, 1984. [PUMA: Group VIB anion;molybdenum bipyrimidine carbonyl carbonyl;ESR radical substitution tributylphosphine]