Five dirhenium(III) compounds, Re2(3,5-(CH3)2ap)4Cl2 (1), Re2(ap)4Cl2 (2), Re2(3-MeOap)4Cl2 (3), Re2(3-Clap)4Cl2 (4), and Re2(3,5-Cl2ap)4Cl2 (5), were synthesized and characterized, where 3,5-(CH3)2ap, ap, 3-MeOap, 3-Clap and 3,5-Cl2ap are 2-(3,5-dimethylanilino)pyridinate, 2-anilinopyridinate, 2-(3-methoxyanilino)pyridinate, 2-(3-chloroanilino)pyridinate and 2-(3,5-dichloroanilino)pyridinate, respectively. Structural studies revealed the Re–Re bond lengths ranging from 2.2214(4) to 2.2262(11) Å, signifying that the dirhenium core maintains its quadruple bond. The asymmetric nature of 2-anilinopyridinate ligands resulted in several possible regioisomers: compounds 1 and 4 adopt a cis-(2,2) arrangement, while compounds 2 and 5 assume trans-(2,2) and (3,1) arrangements, respectively. All five compounds display three (quasi)reversible one electron couples, two oxidations and one reduction, and their electrode potentials correlate linearly with the Hammett constant of the aniline substituent.
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This work was supported in part by the Office of Naval Research (Contract Number N00014-03-1-0531), the National Science Foundation (CHE0242623) and the University of Miami (CCD-diffractometer fund). We thank Dr. G.-L. Xu for advice on the synthesis of HXap ligands, Mr. R. McGuire for examining the emission properties of compounds 1–5.
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