Metal to ligand charge-transfer photochemistry of metal-metal bonded complexes. 5. ESR spectra of stable rhenium-.alpha.-diimine and spin-trapped manganese-.alpha.-diimine radicals

Photochemistry of the metal-metal-bonded complexes [(CO)5MnRu(Me)(CO)2(α-diimine)]. Crystal structure of the photoproduct [(CO)4Mn-μ-(σ(N),σ(N′),ν2(CN)-iPr-PyCa)Ru(Me)(CO)2]

“…The large nitrogen coupling constants observed for both radicals indicate that the unpaired electron is mainly localized on the a-diimine ligand. A similar conclusion was derived from the ESR spectra of the radicals [Mn(CO)3(tBu-DAB)] ", [Re(CO)3(a-diimine)]" and [Cr(CO)n(a-diimine)]- [6,33,34]. As indicated by the values of aRu and a N, this localization increases on going from the 1Pr-PyCa to the ipr-DAB radical complex.…”

“…4(b)] simulation was performed with one Ru (aRu = 3.03 G) and one phosphorus nucleus (ap = 52.11 G), two nitrogens (a N = 4.33 G) and one imine H (a n = 1.20 G). Similar radical adducts [Re(L)(CO)3(tBu-DAB)]" appeared to be formed upon irradiation of [Ph3Sn--Re(CO)3(tBu -DAB)] in the presence of L = PR 3 or pyridine [34].…”

Chemistry of tricarbonylrhenium(I) chelates of azopyrimidines, azoimidazoles and anion radicals thereof

“…4(c)) are observed corresponding to virtually equal coupling with 185; 187 Re (I ¼ 5=2) and 31 P (I ¼ 1=2). This situation has been previously observed in diazabutadiene organometallics [16]. The g-values in all radical species examined by us are only slightly higher than the free-electron value of 2.0023.…”

Photochemistry of tris(pyrazolyl)borate titanium(IV) complexes

“…Therefore, calculation of the values of these constants for the complexes TpTi(III)Cl 2 (THF) (3) and Tp*Ti(III)Cl 2 (THF) (4) makes it possible to evaluate the effect a steric environment has on the electronic spectra of Ti(III) as it goes from Tp to Tp*. The theory for g value predicts gi = 2 and g^= 2(1 À 3f/D), where f is the spin-orbit coupling parameter and D is the energy difference between t 2g ground state and e g excited state [14,15]. With the experimental data obtained from ESR experiments and the electronic spectra of 3 and 4, we can calculate the value of f (Table 1).…”