Peculiarities of the M-π interaction in phosphacymantrene derivatives upon the Mn(CO)3 fragment orientation: Experimental and theoretical electron density study

The results of the single crystal X-ray diffraction analysis of 2,5-diphenylphosphacymantrene (eta(5)-C4H2Ph2P)Mn(CO)(3) (1) and experimental charge density distribution study of [(eta(4)-C4H2Ph2P(O)H)Mn(CO)(3)](-)[NH2Et2](+) (2) are discussed. The resultant density was analyzed using the quantum theory of atoms in molecules (QTAIM). Here, we focused on the analysis of the interaction between the metal atom and the pi-ligand depending on the mutual orientation of the Mn(CO)(3) moiety and the heterocyclic fragment (cis and trans conformers). The electronic structures of cis and trans conformers of both the complexes 1 and 2 have also been studied by ab initio density functional theory calculations, showing rather a good agreement with the experiment. Redistribution of the electron density in the vicinity of the metal atom upon the reorientation of the carbonyl groups causes the changes in the geometric and electronic characteristics of the heterocycle. The most significant changes occur in the molecular topology, in particular, in the connectivity of the metal atom with the it-ligand. (C) 2012 Elsevier B.V. All rights reserved.