文摘
A facile and high-yielding protocol to the known Ti(II) complex trans-[(py)4TiCl2] (py = pyridine) has been developed. Its electronic structure has been probed experimentally using magnetic susceptibility, magnetic circular dichroism, and high-frequency and high-field electron paramagnetic resonance spectroscopies in conjunction with ligand-field theory and computational methods (density functional theory and ab initio methods). These studies demonstrated that trans-[(py)4TiCl2] has a 3Eg ground state (dxy1dxz,yz1 orbital occupancy), which, as a result of spin鈥搊rbit coupling, yields a ground-state spinor doublet that is EPR active, a first excited-state doublet at 鈭?0 cm鈥?, and two next excited states at 鈭?20 cm鈥?. Reactivity studies with various unsaturated substrates are also presented in this study, which show that the Ti(II) center allows oxidative addition likely via formation of [Ti(畏2-R2E2)Cl2(py)n] E = C, N intermediates. A new Ti(IV) compound, mer-[(py)3(畏2-Ph2C2)TiCl2], was prepared by reaction with Ph2C2, along with the previously reported complex trans-(py)3Ti鈺怤Ph(Cl)2, from reaction with Ph2N2. Reaction with Ph2CN2 also yielded a new dinuclear Ti(IV) complex, [(py)2(Cl)2Ti(渭2:畏2-N2CPh2)2Ti(Cl)2], in which the two Ti(IV) ions are inequivalently coordinated. Reaction with cyclooctatetraene (COT) yielded a new Ti(III) complex, [(py)2Ti(畏8-COT)Cl], which is a rare example of a mononuclear 鈥減iano-stool鈥?titanium complex. The complex trans-[(py)4TiCl2] has thus been shown to be synthetically accessible, have an interesting electronic structure, and be reactive toward oxidation chemistry.