The preparations and properties are described of a series of [Rh-2](4+) complexes possessing carboxylates and N-based chelates as ligands. Treatment of Rh-2(O2CR)(4)(MeOH)(2) (R = Me (1), Et (2), Ph (3) or CF3 (4)) with 2 equiv of 2,2’-bipyridine (bpy) in refluxing MeCN leads to the [Rh-2(O2CR)(2)(bpy)(2)](2+) cation (in complexes 5-9). Reaction of 1 with 1,10-phenanthroline (phen), 4,4’-dimethyl-2,2’-bipyridine (Me(2)bpy), 4,4’-diphenyl-2,2’-bipyridine (Ph(2)bpy), and 4,7-diphenyl-1,10-phenanthroline (Ph(2)phen) leads to the analogous cations of complexes 10-13. Complex 6a, [Rh-2(OAc)(2)(bpy)(2)(MeCN)(2)](PF6)(2) . 2MeCN, crystallizes in monoclinic space group P2(1)/a with the following cell parameters at -172 degrees C : a = 14.433(2) Angstrom, b = 12.810(1) Angstrom, c = 22.78(3) Angstrom, beta = 104.42(3)degrees, Z = 4, and V = 3971.2 Angstrom(3). Complex 9, [Rh-2(O2CCF3)(4)(bpy)(2)]. Me2CO crystallizes in triclinic space group with the following cell parameters at 20 degrees C : a = 14.260(4) Angstrom, b = 15.375(4) Angstrom, c = 9.709(2) Angstrom, alpha = 105.98(2)degrees, beta = 97.49(2)degrees, gamma = 70.32(2)degrees, Z = 2, and V = 1925.2 Angstrom(3). Both 6a and 9 contain a singly-bonded [Rh-2](4+) unit with two cis bridging RCO2- groups and two syn-bpy chelate groups in a near-eclipsed conformation about the Rh-Rh vector. Reaction of [Rh-2(tpy)(2)(MeCN)(4)](BF4)(4) (15) (tpy = 2,2’:6’,2 "-terpyridine) with NBu4n(O2CPh) gives [Rh-2(O2CPh)(tpy)(2)(MeCN)(2)](BF4)(3) . MeCN (16). Complex 16 crystallizes in triclinic space group with the following cell parameters at -168 degrees C : a = 11.684(4) Angstrom, b = 20.373(8) Angstrom, c = 10.451(3) Angstrom, alpha = 93.47(2)degrees, beta = 110.53(1)degrees, gamma = 100.03(2)degrees, Z = 2, and V = 2274.1 Angstrom(3). The cation of 16 consists of a [Rh-2](4+) unit with a bridging PhCO2- group and two chelating tpy groups. The solution H-1 NMR properties of complexes 6-13 and 16 show the complexes to retain their solid-state structures on dissolution. The electrochemical properties of 6-13 and 16 were investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) in MeCN. The bis(bpy) and -(phen) complexes 6-8, 10, and 11 show a reversible, one-electron reduction in the range -0.83 to -0.91 V vs ferrocene and an additional, irreversible reduction and an irreversible oxidation; the Ph(2)bpy (12) and Ph(2)phen (13) complexes show a two-electron reversible reduction at -0.61 to -0.76 and a reversible one-electron oxidation at 0.68-0.89 V. Consideration of the potentials as a function of carboxylate and chelate identity leads to the conclusion that the reductions are ligand (chelate)-based. This is supported by an extended Huckel calculation on the model compound [Rh-2(O2CH)(2)(bpy)(2)(HCN)(2)](2+), which shows the LUMO to be a bpy based orbital comprising in-phase, sigma overlap of two bpy pi* orbitals, one on each of the syn-bpy groups. In contrast, complex 16 shows no reversible reduction processes. Complex 6b, [Rh-2(OAc)(2)(bpy)(2)(MeCN)(2)](BF4)(2), in MeCN may be reduced with sodium acenaphthylenide in THF to give deep blue [Rh-2(OAc)(2)(bpy)(2)(MeCN)(2)](BF4) (14) in high yield. The cation of 14 may also be generated by controlled potential electrolysis of 6a in MeCN at -0.99 V and by heating of a solution of 6a or 6b in alcohol.