MASS SPECTROSCOPY OF C5H5MN(CO)3 AND C5H5MN(CO)2 COMPLEXES

The mass spectra of the complex CpMn(CO)3 (Cp = C5H5) and its mono-substituted substituted derivatives CpMn(CO)2L with L = cycloolefin (C5H8, C7H12, C8H14, nor-C7H8, nor-C7H10, maleic anhydride), isonitrile, amine, phosphine and sulfoxide, as well as the compound CpMn(CO)butadiene are listed and the fragmentation patterns described. While the primary fragmentation of CpMn(CO)+3 results in stepwise loss of CO ligands, the first decomposition step of the CpMn(CO)2L+ ions is a simultaneous splitting of both CO groups. However, CpMn(CO)2olefin-π-complexes may loose an olefin or two CO groups in the first step after ionization. During further decomposition of the ion CpMnL+ the ligand L can either be split off as a unit or fragmentated while still coordinated to the CpMn residue or to the Mn atom. Rearrangements sometimes accompany the ligand fragmentation. The ionization potentials of the above complexes and the appearance potentials of the CpMnL+ ions were determined and related to the donor and acceptor qualities of the ligands L. A close relationship has been found between the ionization energies and the CO stretching frequencies of the CpMn(CO)2L compounds as well as between the IP values of the uncoordinated ligands and the corresponding complexes. © 1968.