EFFECTS OF SUBSTITUTIONS ON CYCLOPENTADIENYL RINGS IN COMPLEXES WITH MOLYBDENUM MERCURY BONDS - MO-95 AND HG-199 NMR-STUDIES

NMR data for Mo-95 and Hg-199 nuclei have been obtained for new di- and trimetallic complexes Cp'(CO)(3)MoHgX containing molybdenum-mercury bonds and bulky and/or potentially bifunctional substituted cyclopentadienyl ligands; Cp' =C(5)HMe(2)Ph(2) C(5)Me(4)Bz, C5B5, C(5)H(4)PPh(2) and C(5)ME(4)PPh(2) (Bz=CH2C6H5; Me=CH3; Ph=C6H5); X=Cp'(CO)(3)Mo, Cl, Br, I, 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 Mo-95 chemical shifts is found for the compounds with the same number of different substituents on cyclopentadienyl)rl ligands. An outstanding shielding of Hg-199 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.