Electron diffraction studies of metal phthalocyanines, MPc, where M=Sn, Mg, and Zn (reinvestigation)

The structure of two metal phthalocyanines, MPc where M=Sn and Mg, have bee n determined by gas-phase electron diffraction for the first time; furtherm ore, the structure of ZnPc established earlier by the same technique has be en reanalyzed. The focus of these studies is the position of the metal ion relative to the 16-membered C8N8 ring. Tin(II)phthalocyanine we find to be nonplanar with the Sn(II) ion 1.0(1) Angstrom above the molecular plane in accordance with its structure in crystal established earlier; the two other molecules were found to be planar. Slight nonplanarity of ZnPc found in th e previous study is now removed by a new procedure of structural analysis; this is in accordance with the results of ab initio/DFT calculations for th is molecule performed by Pulay. From comparisons presented here we can conc lude that there is a close structural similarity of metal phthalocyanines i n the gas phase and in crystal. (C) 1999 American Institute of Physics. [S0 021-9606(99)01230-1].