ChemInform Abstract: Five-Coordinate Diphosphine Complexes of the (CoNO)8 Group, and Their Disproportionation Reactions to Cobalt(III) and (Co(NO)2)10 Derivatives.
Abstract
Five-coordinate diphosphine complexes of the (CoNO)8 group are synthesized as demonstrated for the examples (III) or by treating an acetonitrile solution of (Co(OH2)6)(BF4)2 and the diphosphine with NO.
ChemInform Abstract
Five-coordinate diphosphine complexes of the (CoNO)8 group are synthesized as demonstrated for the examples (III) or by treating an acetonitrile solution of (Co(OH2)6)(BF4)2 and the diphosphine with NO. Their stereochemistry and dynamic behavior are studied by 31P(1H) NMR spectroscopy. The mononitrosyl complexes e.g. (III) which contain linearly coordinated Co-NO groups disproportionate in solution in the presence of pseudohalide or halide anions (NCS-, NCO-, N3-, Cl-) to give Co(III) complexes of the type (V) and (Co(NO)2)10 derivatives such as (VI). The IR, electronic, and 31P NMR spectroscopic properties of the Co(III) complexes are consistent with a trans stereochemistry, while those of the (Co(NO)2)10 derivatives suggest a pseudotetrahedral structure with linear NO groups. A possible mechanism of the dismutation reaction is presented which involves the formation of a six-coordinate trans (CoX(NO)(diphosphine)2)+ intermediate containing a strongly bent Co-NO moiety.
