Solid-State Synthesis of Molybdenum and Tungsten Porphyrins and Aerial Oxidation of Coordinated Benzenethiolate to Benzenesulfonate

2012-06-04T00:00:00Z (GMT) by Goutam Nandi Sabyasachi Sarkar
A new route is developed for the synthesis of molybdenum and tungsten porphyrins using [M­(NO)2py2Cl2] (M = Mo, W) as the metal source and TPP (dianion of 5,10,15,20-meso-tetraphenylporphyrin) in the benzoic acid melt. Complexes [MoVO­(TPP)­(OOCPh)] (1) and [WVO­(TPP)­(OOCPh)] (2) are isolated in almost quantitative yield. These are characterized by single-crystal X-ray structure analysis, electron paramagnetic resonance, electronic and IR spectroscopy, and magnetic moment measurements. Benzenethiol substitutes for PhCOO in 1, forming an intermediate thiolato complex that responds to the intramolecular redox reaction across the MoV–SPh bond to yield [MoIVO­(TPP)] (3). Under an excess of benzenethiol, PhS is coordinated to the vacant site in 3, which under aerial oxidation is oxidized to benzenesulfonate to form [MoVO­(TPP)­(O3SPh)] (4). 2 undergoes similar aerial oxidation chemistry albeit slowly.