Synthesis, bonding and reactivity of a terminal titanium alkylidene hydrazido compound.

We report a detailed study of the reactions of the Ti=NNCPh2 alkylidene hydrazide functional group in [Cp*Ti{MeC(NiPr)2}(NNCPh2)] (8) with a variety of unsaturated and saturated substrates. Compound 8 was prepared from [Cp*Ti{MeC(NiPr)2}(NtBu)] and Ph2CNNH2. DFT calculations were used to determine the nature of the bonding for the Ti=NNCPh2 moiety in 8 and in the previously reported [Cp2Ti(NNCPh2)(PMe3)].

Site selectivity and reversibility in the reactions of titanium hydrazides with Si-H, Si-X, C-X and H+ reagents: Ti=N(α) 1,2-silane addition, Nβ alkylation, Nα protonation and σ-bond metathesis.

We report a combined experimental and computational comparative study of the reactions of the homologous titanium dialkyl- and diphenylhydrazido and imido compounds Cp*Ti{MeC(N(i)Pr)(2)}(NNR(2)) (R = Me (1) or Ph (2)) and Cp*Ti{MeC(N(i)Pr)(2)}(NTol) (3) with silanes, halosilanes, alkyl halides and [Et(3)NH][BPh(4)]. Compound 1 underwent reversible Si-H 1,2-addition to Ti=N(α) with RSiH(3) (experimental ΔH ca. -17 kcal mol(-1)), and irreversible addition with PhSiH(2)X (X = Cl, Br).

Si-H and Si-Cl bond activation reactions of titanium hydrazides with silanes and subsequent Ti-H/E-H (E = Si or H) σ-bond metathesis.

The Ti=NNMe(2) group of Cp*Ti{MeC(N(i)Pr)(2)}(NNMe(2)) undergoes 1,2-addition with Si-Cl and reversible addition with Si-H bonds of RSiH(2)X (R = Ph or Bu; X = Cl or H). Labeling studies show that the so-formed silylhydrazide-hydride products react with primary silanes or H(2)via σ-bond metathesis between Ti-H and either Si-H or H-H.

Single and double substrate insertion into the Ti=N(alpha) bonds of terminal titanium hydrazides.

Nitriles, CO(2) and isocyanates undergo net single or double insertion reactions into the Ti=N(alpha) multiple bonds of terminal titanium hydrazides. These are the first such examples of this type of reactivity for any transition metal hydrazide complex.