The molecular structure, bonding, and energetics of oxovanadium phthalocyanine: an experimental and computational study

Abstract

A mass spectrometric study of saturated vapor over oxovanadium phthalocyanine showed the thermal stability and monomeric vapor composition of this compound. The molecular structure of oxovanadium phthalocyanine (VOPc) was determined using a combination of gas-phase electron diffraction (GED), mass spectrometry, and quantum chemical calculations. According to GED, the VOPc molecule has C4v symmetry. Experimental structural parameters are in good agreement with the parameters obtained by UB3LYP/cc-pVTZ calculations. The vanadium atom has a five-coordinated square-pyramidal geometry, being shifted above the plane of the four isoindole nitrogen atoms by 0.576(14) A. The parameters of the square pyramid VN4 are r h1(V–N) = 2.048(7) A, r h1(N···N) = 2.780(12) A. The vanadium–oxygen bond length is r h1(V–O) = 1.584(11) A. NBO analysis shows polar character of coordination bonds with significant covalent contribution and pronounced direct donation. X-ray crystallography and GED give different coordination bond lengths according to the different physical meaning of the parameters obtained by these methods. The enthalpy of sublimation [∆H s o (593–678 K)] is 53.3 ± 0.8 kcal/mol.