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Zwitterionic nickel(II) compounds with a borate-containing anionic bidentate phosphine ligand (PBP − ) have been synthesized and some of them crystallographically characterized. The methyl complex, (PBP − )Ni + CH 3 (NCCH 3 ), reacts with H 2 to form an 12-membered macrocycle containing three Ni nuclei and reacts with carbon monoxide (CO) to afford the acetyl complex (PBP − )Ni + COCH 3 (CO). The square planar acetyl complex is stable in solution under 1 atm of CO but undergoes irreversible decomposition under high CO pressure at room temperature. X-Ray crystallographic characterization of a decomposition product revealed fragmentation of the anionic borate under high pressure. (PBP − )Ni + COCH 3 (CO) is an active catalyst for ethylene-CO copolymerization, but its productivity is low likely due to its instability under high CO pressure. [ABSTRACT FROM AUTHOR]

Abstract: The new pyridine-2-carboxaldehyde adduct, Re(CO)3(NC6H5C(O)H)Cl 1, and previously reported complex Re(CO)3(NC6H5C(O)H)Br 2 react with aniline derivatives sulfanilamide or 4-aminofluorescein in methanol giving Schiff base conjugates Re(CO)3(pyca-R)X (pyca = pyridinecarbaldehyde imine, X = Cl, Br), 3–6. Pre-isolation of compounds 1 and 2 provides a convenient method for preparing conjugate complexes in addition to the known methods of ligand synthesis and one-pot reactions. All new compounds were completely characterized, and compound 1 and the sulfanilamide derivatives 3 and 4 were structurally elucidated by X-ray crystallography. [Copyright &y& Elsevier]