The new heteroleptic paddlewheel complexes cis-[Rh-2(mu-form)(2)(mu-np),][BF4](2), where form = p-ditolylformamidinate.(DTolF) or p-difluorobenzylforMamidinate (F-form) and np = 1,8-napthyridyine, and cis-Rh-2(mu-form)(2)(mu-npCOO)(2) (npCOO(-) = 1,8-naphthyridine-2-carboxylate), were synthesized and characterized. The complexes absorb strongly throughout the ultraviolet (lambda(max) = 300 nm, epsilon = 20 300 M-1 cm(-1)) and visible regions (lambda(max) = 640 nm epsilon = 3500 M-1 cm(-1)), Making them potentially useful new dyes with panchromatic light absorption for solar energy conversion applications. Ultrafast and nanosecond transient absorption and time resolved infrared spectroscopies were used to characterize the identity and dynamics of the excited states, where singlet and triplet Rh-2/form-to.maphthyridine, metal/ligand-to-ligand charge-transfer (ML-LCT) excited states were observed in all four complexes. The hpCOO(-) complexes exhibit red-shifted absorption profiles extending into the near-IR and undergo photoinitiated electron transfer to generate reduced methyl viologen, a species that persists in the presence of a sacrificial donor. The energy of the triplet excited state of each complex was estimated from energy-transfer quenching experiments using a series of organic triplet donors (E((3)pi pi*) from 1.83 to 0.78 eV). The singlet reduction (+0.6 V vs Ag/AgCl) potentials, and singlet and triplet oxidation potentials (-1.1 and 0.5 V vs Ag/AgC1, respectively) were determined. Based on the excited-state lifetimes and redox properties, these complexes represent a new class of light absorbers with potential application as dyes for charge injection into semiconductor solar cells and in sensitizer-catalyst assemblies for photocatalysis that operate with irradiation. from the ultraviolet to similar to 800 nm.