Dinitrogen complexes derived from tricarbonyl(η6-hexaethylbenzene)chromium(0): crystal and molecular structure of µ-dinitrogen-bis[dicarbonyl(η6-hexaethylbenzene)chromium(0)]–toluene (1/1)

Abstract

Photolysis under nitrogen of toluene solutions of mixtures of tricarbonyl(η⁶-hexaethylbenzene)chromium(0), (1), and diphenylacetylene gave dicarbonyl(dinitrogen)(η⁶-hexaethylbenzene)chromium(0), (2), and µ-dinitrogen-bis[dicarbonyl(η⁶-hexaethylbenzene)chromium(0)], (3), as the only identifiable organometallic products. A decoalescence phenomenon observed in the 90.56-MHz ¹³C-{¹H} solution n.m.r. spectrum of (3) is attributed to slowed ethyl group rotation and a barrier (ΔG₃₀₀^‡) of 46.0 ± 3.0 kJ mol^–1 for this process has been determined from lineshape fitting studies. The crystal and molecular structure of (3) has been determined and the molecule shown to be a dinitrogen-bridged dinuclear chromium complex with C_2h molecular symmetry. The co-ordinated hexaethylbenzene has been found to adopt a 1,3,5-distal-2,4,6-proximal methyl conformation.