Redox Potential Tuning of Dimolybdenum Systems through Systematic Substitution by Guanidinate Ligands.

We report the synthesis and characterization of a series of dimolybdenum paddlewheel complexes of the type Mo(DAniF)(hpp) ( = 1-3), where DAniF is the anion of ,'-di--anisyl-formamidine and hpp is the anion of 1,3,4,6,7,8-hexahydro-2-pyrimido[1,2-]pyrimidine. The effect on the electronic structure of these tetragonal paddlewheel dimolybdenum compounds was studied upon systematic substitution of formamidinate ligands by the more basic guanidinates. Mo-Mo distances in the paddlewheel structures decreased upon guanidinate ligand substitution, and were found to be 2.

Hydrogen gas generation using a metal-free fluorinated porphyrin.

Free-base -tetra(pentafluorophenyl)porphyrin, , is electrocatalytically active for hydrogen gas generation in the presence of -toluenesulfonic acid. The electrochemical potential of hydrogen evolution (-1.31 V Fc/Fc in THF) is comparable to those of metal containing electrocatalysts such as metallated porphyrins or other metallated macrocycles.