Reactions of Titanium Imides and Hydrazides with Boranes

We report the first reactions of titanium imido, alkylidene hydrazido, and dimethylhydrazido compounds with the boranes H2BTex, 9-BBN, HBArF2, and HBPin (Tex = tert-hexyl; ArF = C6F5). Reactions of Cp*Ti­{MeC­(NiPr)2}­(NTol) with H2BTex, 9-BBN, or HBArF2 resulted in the hydride-bridged adducts Cp*Ti­{MeC­(NiPr2)2}­{N­(Tol)­HBRR′} without B–H bond cleavage. Cp*Ti­{MeC­(NiPr)2}­(NNCPh2) (4) reacted with HBArF2 via a sequence of steps involving adducts at the β- and then α-nitrogen of the NNCPh2 ligand, before slow 1,2-addition of B–H across the NCPh2 double bond of 4, forming Cp*Ti­{MeC­(NiPr)2}­{NN­(BArF2)­CHPh2} (17). The other boranes reacted immediately with 4 to form homologues of 17. These products are the first examples of borylhydrazido­(2-) complexes. Reaction of Cp*Ti­{MeC­(NiPr2)2}­(NNMe2) (2) with HBArF2 gave the hydride-bridged adduct Cp*Ti­{MeC­(NiPr2)2}­{N­(NMe2)­HBArF2}, whereas with HBPin B–H bond cleavage occurred to form the borylhydrazide­(1-)-hydride Cp*Ti­{MeC­(NiPr)2}­(H)­{N­(BPin)­NMe2}. Finally, reaction of 2 with 9-BBN dimer resulted in H2 elimination and formation of Me2NBC8H14 and Cp*Ti­{MeC­(NiPr)2}­(NBC8H14), a rare example of a borylimido compound.