Synthesis and Structure of Cp*2TiH, Cp*2TiH2Li(tmed), and [Cp*2TiOLi(THF)]2

The solid-state crystal structure of the d 1 hydride Cp* 2 TiH shows that it has a bent sandwich structure with an open Cp*(centroid)−Ti−Cp*(centroid) angle of 150°. The crystal structure contains two molecules in the asymmetric unit, and the hydridic hydrogen atom is located and refined with isotropic thermal parameters to a Ti−H distance of 1.69(5) and 1.84(4) Å in each independent molecule; the average Ti−H distance is 1.76 Å. In each molecule, the Ti−H vector lies on the idealized C 2 axis of the bent metallocene. The addition of n -BuLi and Me 2 NCH 2 CH 2 NMe 2 (tmed) in hexane to Cp* 2 TiH or the addition of [Li(tmed)] 2 C 10 H 8 to Cp* 2 TiCl gives the anionic dihydride Cp* 2 Ti(μ-H) 2 Li(tmed). The hydride atoms are not located in the X-ray diffraction experiment, but electron paramagnetic resonance spectra show coupling to two equivalent hydrogen nuclei, A H iso = 9.6 G. In addition, coupling to 7 Li, confirmed by the preparation of the 6 Li isotopomer, shows that the unpaired electron couples with each hydridic hydrogen and lithium nucleus. The proposed structure has two hydride ligands bridging the Cp* 2 Ti and Li(tmed) fragments. Water in tetrahydrofuran (THF) reacts with Cp* 2 Ti(μ-H) 2 Li(tmed) to give the dimer, [Cp* 2 TiOLi(THF)] 2 . Its X-ray structure shows that the two Cp* 2 TiO fragments are joined together by the Li(THF) fragments such that the Li 2 O 2 unit is a square as found in dimeric lithium alkoxides; in this case, the alkoxide is the metallocene Cp* 2 TiO - . Variable-temperature magnetic susceptibility shows that the unpaired electrons on each Cp* 2 TiO - fragment are not coupled down to 5 K.