Effects of substitutions on cyclopentadienyl rings in complexes with molybdenum-mercury bonds. 95Mo and 199Hg NMR studies

Abstract

NMR data for 95Mo and 199Hg nuclei have been obtained for new di- and trimetallic complexes Cp′(CO) 3MoHgX containing molybdenum-mercury bonds and bulky and/or potentially bifunctional substituted cyclopentadienyl ligands; Cp′=C 5HMe 2Ph 2, C 5Me 4Bz, C 5Bz 5, C 5H 4PPh 2 and C 5Me 4PPh 2 (Bz=CH 2C 6H 5; Me =CH 3; Ph=C 6H 5); X=Cp′(CO) 3Mo, Cl, Br, 1, SCN. They are discussed within the context of our earlier results reported for analogous complexes with the cyclopentadienyl ligands bearing methyl groups. With the exception of phenyl substituted rings, a rather narrow range of 95Mo chemical shifts is found for the compounds with the same number of different substituents on cyclopentadienyl ligands. An outstanding shielding of 199Hg nuclei, observed in complexes bearing the rings with Bz, PPh 2 and Ph substituents instead of the methyls, is assigned to the intramolecular substituent-mercury interactions.