Direct Access to Terminal Titanocene Hydrazides via Bis(η⁵:η¹‑pentafulvene)titanium Complexes and 1,1-Diphenylhydrazine

The formation of the titanocene hydrazido complex <b>2</b> via double N–H bond activations at ambient temperature of 1,1-diphenylhydrazine by the use of bis­(η⁵:η¹-adamantylidenepentafulvene)titanium complex <b>1</b> have been investigated. Starting from the titanium hydrazido complex <b>2</b>, [2 + 2] cycloaddition and bond activation reactions are realized. In reaction with carbodiimides, the asymmetric N,N-bound ureato(2−) product <b>3</b> is observed. By use of nitriles, in addition to the [2 + 2] cycloaddition, the insertion of a second equivalent of the nitrile into the Ti–N bond is found (<b>4</b>). By reaction of <b>2</b> with carbon disulfide the symmetric S,S-bound thioureato(2−) complex <b>5</b> is isolated, whereas in reaction with carbon monoxide the cleavage of the N–N bond of the hydrazide unit is observed, resulting in the formation of the titanocene monocyanate <b>6</b>. In contrast to the [2 + 2] cycloaddition reactions, for sterically demanding boranes such as 9-borabicyclo[3.3.1]­nonane and catecholborane the hydroboration of the TiN double bond is observed, leading to the titanocene hydride complex <b>7</b> and the titanium­(III) cation <b>8