1,2-Addition of Formic or Oxalic Acid to ^–N{CH₂CH₂(PiPr₂)}₂-Supported Mn(I) Dicarbonyl Complexes and the Manganese-Mediated Decomposition of Formic Acid

Abstract

(PNHP)Mn(CO)2 (I) carboxylate complexes (PNHP = HN{CH2CH2(PiPr2)}2) were prepared via 1,2-addition of either formic or oxalic acid to (PNP)Mn(CO)2 (PNP = the deprotonated, amide form of the ligand –N{CH2CH2(PiPr2)}2). The structural and spectral properties of these complexes were compared. The manganese formate complex was found to be dimeric in the solid state and monomeric in solution. Half an equivalent of oxalic acid was employed to form the bridging oxalate dimanganese complex. The catalytic competencies of the carboxylate complexes were assessed, and the formate complex was found to decompose formic acid catalytically. Both dehydrogenation and dehydration pathways were active as assessed by the presence of H2, CO2, and H2O. The addition of LiBF4 exhibited a strong inhibitory effect on the catalysis.