image-initiated N–N bond cleavage in a thiotetrazole ligand in a cyclopentadienylchromium complex

The tetrazolylthiolato complex CpCr(CO)3(STz) (4a) was obtained from the facile reaction between [CpCr(CO)3]2 (Cp = C5H5) (1) and 5,5′-dithiobis(1-phenyl-1H-tetrazole), (abbrev. (PhN4CS)2 or (STz)2). Further reaction of 4a with 1 under thermolytic conditions led to isolation of low yields of the cubane-like complexes Cp4Cr4S3(μ3-N3Ph) (5), Cp4Cr4S2(μ3-CO)(μ3-NCtriple bond; length of mdashCrCp(CO)2) (6), Cp4Cr4S2(μ3-N3Ph)(μ3-NCtriple bond; length of mdashCrCp(CO)2) (7) and Cp4Cr4SO2(μ3-NPh) (8), containing μ3-phenyltriazenido, imidocarbyne and phenylimido groups at the corners of cuboids, in addition to μ3-sulfide, oxo or carbonyl groups. The predominant products were the decarbonylation derivative of 1, i.e. [CpCr(CO)2]2(Crtriple bond; length of mdashCr) (9), together with [CpCr(CO)2]2S (10) and its thermolytic cuboidal derivatives, mainly Cp4Cr4S2O2 (11) and Cp4Cr4S4 (13). 1-initiated homolytic fragmentation of the tetrazole ring was proposed to rationalize the formation of the derived cubanes. The structures of the complexes 4a, 6–8 and 11 have been determined by single X-ray diffraction analysis.