Radical non-radical states of the [Ru(PIQ)] core in complexes (PIQ=9,10-phenanthreneiminoquinone)

摘要

9,10-Phenanthreneiminosemiquinonate anion radical (PIQ(center dot-)) complexes of ruthenium of types trans-[Ru-vertical bar vertical bar(PIQ(center dot-))(PPh3)(2)(CO)Cl] (1) and trans-[Ru-vertical bar vertical bar vertical bar(PIQ(center dot-))(PPh3)(2)Cl-2] (2) are reported. Reactions of 1 and 2 with I-2 afford trans-[Ru-vertical bar vertical bar vertical bar(PIQ(center dot-))(PPh3)(2)(CO)Cl]I-+(3)-center dot 1/2CH(2)Cl(2) (1(+)I(3)(-)center dot 1/2CH(2)Cl(2)) and trans-[Ru-2(vertical bar vertical bar vertical bar)(PIQ(center dot-))(2)(PPh3)(2)(mu-Cl)(3)]I-+(3)-center dot 1/4I(2)center dot 1/4toluene) (3(+)I(3)(-)center dot 1/4I(2)center dot 1/4toluene), while the reaction of 2 with Br-2 yields a 9,10-phenanthreneiminoquinone (PIQ) complex of the type mer-[Ru-vertical bar vertical bar vertical bar(PIQ)(PPh3)Br-3]center dot 1/2CH(2)Cl(2) (4 center dot 1/2CH(2)Cl(2)). In comparison, the reaction of trans-[Ru-vertical bar vertical bar vertical bar(PQ(center dot-))(PPh3)(2)Cl-2] (2(PQ)), a 9,10-phenanthrenequinone (PQ) analogue of 2 affords only trans-[Ru-vertical bar vertical bar vertical bar(PQ)(PPh3)(2)Cl-2](+)Br3(-) (5(+) Br-3(-)). Considering the X-ray bond parameters, EPR spectra and the atomic spin densities obtained from the density functional theory (DFT) calculations, 1 is defined as a PIQ(center dot-)(average C-O/N and C-C lengths, 1.280(2) and 1.453(3) angstrom) complex of ruthenium(vertical bar vertical bar) while 4 is a neutral PIQ (average C-O, C-N, C-C and C-O/N lengths, 1.248(7), 1.284(7), 1.485(8) and 1.266(7) angstrom) complex of the ruthenium(III) ion. The single crystal X-ray bond parameters proposed that 1(+)I(3)(-)(average C-O/N and C-C lengths, 1.294(8) and 1.449(9) angstrom) and 2 (average C-O/N and C-C lengths, 1.289(2) and 1.447(4) angstrom) are PIQ(center dot-)complexes of ruthenium(III), while the 3(+) ion (average C-O/N and C-C lengths, 1.288 +/- 0.004 and 1.450 +/- 0.017 angstrom) is a co-facial bi-octahedral complex of ruthenium(III). In contrast, the 5(+) ion is a PQ complex of the ruthenium(III) ion. EPR spectra and the calculated atomic spin densities authenticated that the 2(+) ion obtained after constant potential coulometric oxidation of 2 is a PIQ complex of ruthenium(III), while the 2(-) ion is a hybrid state of [Ru-vertical bar vertical bar(PIQ(center dot-))] and [Ru-vertical bar vertical bar vertical bar(PIQ(2-))] states. It is observed that the PIQ(center dot-) state in which spin is more localized on the nitrogen (similar to 38% in 1 and similar to 35% in 2(-) ion) is stable and the coordination of the PIQ(2-) state is not observed in this study. Redox activities, UV-vis/NIR absorption spectra and their origins and the spectroelectrochemical measurements for 2 -> 2(+), 2 -> 2(-) and 3(+) -> 3(2+) conversions are analyzed.