ANSA-METALLOCENE DERIVATIVES .20. AN ASSIGNMENT OF H-1-NMR AND C-13-NMR SIGNALS IN ANSA-METALLOCENE COMPLEXES WITH 16-ELECTRON AND 18-ELECTRON CONFIGURATION

The NMR signals of cyclopentadienyl ring protons and C atoms in ansa-metallocene derivatives of general type (CH3)4C2(C5H4)2M(X,L)n, with a 16-electron configuration, i.e. with MXn = TiF2, TiCl2, TiBr2, TiI2 or Ti(CH3)2, and with an 18-electron configuration, i.e. with MLn = Ti(CO)2, Ti(P(CH3)3)2, Cr(CO) or Fe, have been assigned to the α- and β-ring positions by nuclear Overhauser effect and selective decoupling studies. Whereas the α-proton resonances appear at higher fields than those for the β-protons in all the complexes with the 16-electron configuration, the opposite is the case for the 18-electron ansa-metallocene derivatives studied. © 1990.