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Abstract: High-resolution Fourier transform absorption and luminescence spectroscopy reveal axial and rhombic zero-field splittings of the spin-forbidden electronic origins of V3+ in NaMgAl(ox)3·9H2O (ox=oxalate) single crystals below 25K. The temperature dependence of the integrated absorption of the split features display behavior consistent with a Boltzmann distribution within the zero-field split 3Â2 ground state of V3+. Weak luminescence is observed in the near-IR from the lowest energy spin-forbidden transition with a luminescence lifetime of less than 0.5μs at 11K and an estimated quantum efficiency of the order of 10−5. [Copyright &y& Elsevier]

Imido ligand transfer occurs when Os(TTP)(NC6H4NO2)2 (TTP=dianion of 5,10,15,20-tetra(p-tolyl)porphyrin) is treated with excess phosphine. The rate of transfer to PMe3−xPhx (x=0, 1, 2, 3) and P(OMe)2Ph depends on the basicity and the steric properties of the phosphine. No imido ligand transfer is observed when Os(TTP)(NC6H4NO2)2 is treated with excess dimethyl fumarate, styrene, cis-cyclooctene, or 2,3-dimethylbutene under a variety of reaction conditions. [Copyright &y& Elsevier]

Reaction of [Ru(TPP)]2 with p-nitrophenylazide yields Ru(TPP)(NC6H4NO2)2 in high yield as indicated by 1H NMR spectroscopy. All attempts to isolate a pure crystalline sample of this new bis(arylimido)ruthenium porphyrin were unsuccessful due to its high reactivity. Os(4-Cl-TPP)(NC6H4NO2)2 was synthesized and structurally characterized. The structure of Os(4-Cl-TPP)(NC6H4NO2)2 is similar to the previously characterized Os(TTP)(NC6H4NO2)2 but quite different from other bis(imido)osmium complexes. The imido bonds in the new bis(arylimido)osmium porphyrin are bent with average Os&z.sbnd;N&z.sbnd;C bond angles of 142.5° suggesting the imido ligands act as four-electron donors. The eclipsed orientation of the imido ligands indicates the presence of one π bonding and one non-bonding molecular orbital. In solution, 1H NMR spectroscopy indicates the structure of Os(4-Cl-TPP)(NC6H4NO2)2 is dynamic with free rotation around the imido N&z.sbnd;C and N&z.sbnd;Os bonds. [Copyright &y& Elsevier]