Electron spin resonance studies of bis(η-cyclopentadienyl) compounds of molybdenum and tungsten

A series of cations of the general formula [M(cp)₂(X)Y]⁺ (M = Mo or W; X and Y are equivalent to uninegative unidentate ligands; cp = ?-cyclopentadienyl), have been produced by oxidation with chemical oxidants, by electrolysis, or by exchange reactions. The e.s.r. spectra of these paramagnetic species have been studied in solution and the values and solution hyperfine coupling constants are discussed. Spectra of glasses of some of the cations are also presented.