Bis(N,N) Chelated Rhenium(III): The Cl Family

Article abstract of DOI:10.1039/DT9920001883

The reaction of mer- with 2-(arylazo)pyridines (L) affords dark green, diamagnetic, 1:1 electrolytes Cl (aryl of L = Ph, m-MeC6H4 or p-ClC6H4).The ReCl2 moiety is cis (two Re-Cl stretches) and the cation has an overall two-fold symmetry axis ((1)H NMR spectra).The co-ordinated pyridine-nitrogen atoms and azo-nitrogen atoms of each ligand are assigned relative trans and cis geometries respectively.The N=N stretching frequencies are low (1280-1290 cm^-1) implying significant Re(t₂)-azo(?^*) back bonding.In MeCN solution three nearly reversible redox couples occur with E_1/2 values of ca. 0.9 V and ca -0.4, ca. -0.8 V (azo redox) vs. the saturated calomel electrode (SCE).A metal-to-ligand charge-transfer (m.l.c.t) absorption is observed near 600 nm.The reduction potentials and m.l.c.t. frequencies are mutually consistent.The remarkable spectral and electrochemical similarities between IIIL2Cl2>Cl and IIL2Cl2> are noted and rationalised.

Full text of DOI:10.1039/DT9920001883

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