Substituent and Isomer Effects on Structural, Spectroscopic, and Electrochemical Properties of Dirhodium(III,II) Complexes Containing Four Identical Unsymmetrical Bridging Ligands

Substituent and isomer effects on the structural, spectroscopic, (UV-visible and ESR) and electrochemical properties of dirhodium(III,II) complexes containing four identical unsymmetrical bridging ligands are reported for seven related compounds of the type Rh2(L)4Cl where L = 2-(2-fluoroanilino)pyridinate (2-Fap), 2-(2,6-difluoroanilino)pyridinate (2,6-F2ap), 2-(2,4,6-trifluoroanilino)pyridinate (2,4,6F3ap), or 2-(2,3,4,5,6-pentafluoroanilino)pyridinate (F5ap) anion. Rh2(2-Fap)4Cl exists only in a (4,0) isomeric conformation while Rh2 (2,6-F2ap)4Cl, Rh2(2,4,6-F3ap)4Cl, and Rh2(F5ap)4Cl exist as both (4,0) and (3,1) isomers. It had earlier been demonstrated that Rh2 (L)4Cl complexes can adopt different geometric conformations of the bridging ligands, but the current study provides the first example where two geometric isomers of Rh25+ complexes are obtained for one compound using the same synthetic procedure. The synthesis, structural, spectroscopic, and/or electrochemical properties of (3,1) Rh2(2,6-F2ap)4CN and (4,0) Rh2(2,4,6-F3ap)4(C(identical)C)2Si (CH3)3 are also reported and the data on these compounds is discussed in light of their parent complexes, (3,1) Rh2(2,6-F2ap)4Cl and (4,0) Rh2(2,4,6-F3ap)4Cl.