Synthesis and characterization of pentachlorophenyl-metal derivatives with d0 and d10 electron configurations

By reaction of [TiCl3(thf)(3)] with LiC6Cl5, the homoleptic organotitanium(III) derivative [Li(thf)(4)][Ti-III(C6Cl5)(4)] (1) has been prepared as a paramagnetic (d(1), S = 1/2, g(av), = 1.959(2)), extremely air-sensitive compound. Oxidation of 1 with [N(C6H4 Br-4)(3)][SbCl6] gives the diamagnetic (d(0)) organotitanium(IV) species [Ti-IV(C6Cl5)(4)] (2). Compounds 1 and 2 are also electrochemically related (E-1/2 = 0.05 V): The homoleptic, diamagnetic (d(10)) compounds [N(PPh3)(2)][Tl(C6Cl5)(4)] (3) and [Sn(C6Cl5)(4)] (4) have also been prepared. Nearly tetrahedral environments have been found for the d(0), d(10), and d' metal centers in the molecular structures of compounds(i)2-4 as well as in that of [Li(thf)(2)(OEt2)(2)][Ti-III(C6Cl5)(4)].CH2Cl2 (1') (X-ray diffraction). The reaction of the heavier Group 4 metal halides, MCl4 (M = Zr, Hf) with LiC6Cl5 in the presence of [NBu4]Br gives, in turn, the heteroleptic species [NBu4][M(C6Cl5)(3)Cl-2] (M = Zr (5), Hf (6)). Compounds 5 and 6 are isomorphous and isostructural, with the metal center in a trigonal-bipyramidal (TBPY-5) environment defined by two axial Cl ligands and three equatorial C6Cl5 groups (X-ray diffraction). No redox features are observed for compounds 3-6 in CH2Cl2 solution between -1.6 and +1.6 V.