DI-MU-HYDRIDO-BIS(DICYCLOPENTADIENYLTITANIUM(III)), A TRANSITION METAL COMPLEX WITH A DIBORANE-LIKE DOUBLE HYDROGEN BRIDGE

Di-μ-hydrido-bis(di-π-cyclopentadienyltitanium(III)) (1) is formed by reaction of solid (π-C5H5)2Ti-(CH3)2 with gaseous hydrogen. 1 is characterized by its ir spectrum (di-μ-hydridotitanium band at 1450 cm−1) and by the following reactions: thermal decomposition of 1 yields titanocene dimer and 1 mol of H2; 1 and 1,3-pentadiene give π-(1,3-dimethyl)allyltitanocene; 1 and diborane afford the titanocene borohydride (π-C5H5)2TiBH4; reaction of 1 with HCl yields titanocene dichloride and hydrogen; DCl gives largely HD, as expected for a hydride. 1 is a diamagnetic deep violet compound of moderate stability, pyrophoric in air. Tetrahydrofuran at room temperature first cleaves the compound to a monomeric paramagnetic adduct, the epr spectrum of which shows the presence of one hydride ligand, then leads to further degradation. Triphenylphosphine in tetrahydrofuran solution cleaves 1 to a monohydride-monophosphine complex, identified again by its epr spectrum. Like other transition metal compounds with hydrogen bridge bonds, 1 appears to contain a metal-metal bond. In contrast to the acidic character of the bridge hydrogen in other transition metal complexes, however, 1 behaves like a typical hydride. © 1969, American Chemical Society. All rights reserved.