Organometallic iridium(III) and rhenium(I) complexes with lumazine, alloxazine and pterin derivatives

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Journal of Organometallic Chemistry, 589 (1): 2--10 (1999)
DOI: 10.1016/S0022-328X(99)00294-6


Two organometallic complex fragments with 5d6 configurated metal centers of different character, electrophilic IrIIICp*Cl+ and p-donating ReI(CO)3Cl, were used as probes in compds. contg. 1,3-dimethyllumazine (DML), 1,3-dimethylalloxazine (DMA), 2-pivaloylpterin (PP) and 6-methyl-2-pivaloylpterin (MPP) as biochem. relevant ligands. Evidence from spectroscopy (NMR, IR, UV-visible) in aprotic solvents points in most cases to the O4 and N5 atoms as chelate donors for metal binding. For (DMA)IrIIICp*Cl(PF6) this was substantiated by a crystal structure anal. With PP, however, an Ir(III) compd. with pivaloyl-coordinated metal was obtained. Whereas both the IrIII and Re1 complexes of the good p acceptor ligand DMA can be reduced reversibly and thus studied by (spectro)electrochem. (IR, UV-visible, EPR: ligand-centered 1-electron redn.), the DML system exhibits such behavior only for the IrIII species. The complexes of the 2-pivaloylpterins showed only irreversible redn. on SciFinder(R)



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