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In an attempt to prepare an alkylidene complex of chromium, the metallacycle, Cp * Cr(L)(CH 2 ) 2 Si(CH 3 ) 2 (L=THF), was treated with 2,2'-bipyridine. Instead of producing the desired trimethylsilylmethylidine complex, a new complex (η 5 -(pentamethylcyclopentadienyl)(2(2,2-dimethyl-2-silapropyl)-1,2-dihydro[2,2']bipyridine-1,3-diyl)chromium(III), 1) with a methylene bridge between silicon and the C 2 carbon of the bidentate 2,2'-bipyridine ligand was formed. The modified bipyridine ligand contains one carbon and two nitrogen donor atoms (CNN ligand). When 1 was treated with [Cp 2 Fe] + [PF 6 ] - , oxidative dimerization occurred giving a dimer dication (2) linked at the C 3 carbon atoms of each 2,2'-bipyridine ligand. This dimer was isolated as the hexafluorophosphate salt. In the present work the electrochemical behavior of 1 and 2 has been explored and it has been shown that anodic oxidation of 1, like the chemical oxidation, produces 2 by way of dimerization of an initially formed transient cation. The dimerization rate constant was 2 × 10 4 M -1 s -1 and the equilibrium constant for dimerization must exceed 5 × 10 6 M -1 . Studies of the cathodic reduction of 2 show that it undergoes an overall two-electron reduction giving mainly 1 as product. The reduction apparently proceeds by one-electron reduction to a detectable intermediate monocation that dissociates to 1 and the cation of 1 which in turn is reduced to 1. It was also found that 2 undergoes an irreversible two-electron oxidation, the products of which were not identified.

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Fine structure has been observed in the fluorescence and excitation spectra of Eu+2 in and in the fluorescence spectrum of Eu+2 in . The fine structure in the fluorescence of Eu+2 in is identified as a zero phonon line with many sharp phonon replicas. The fine structure in its excitation spectrum is due to the closely spaced energy levels in the excited state produced by a strong exchange interaction splitting of the 4f65d states. The fine structure in the fluorescence of Eu+2 in is due to the normal splitting of the 4f7 excited state and the dominance of 4f7 → 4f7 transitions.