Stabilisation of a Strontium Hydride with a Monodentate Carbazolyl Ligand and its Reactivity.

Abstract

The molecular strontium hydride 2[(dtbpCbz)SrH(L)]2 (L = benzene, toluene) was isolated and stabilized by employing a sterically demanding carbazole ligand (dtbpCbz = 1,8-bis(3,5-ditert-butyl-phenyl)-3,6-ditertbutylcarbazolyl). Compound 2 was synthesized via phenylsilane metathesis with the corresponding amide (dtbpCbz)SrN(SiMe3)2 and characterized by 1HNMR, XRD and vibrational spectroscopy methods. We further investigated the stoichiometric reactivity of 2 towards carbon monoxide, azobenzene and trimethylsilylacetylene, showing three distinct reactivity pathways: addition, reduction and deprotonation. The reaction of 2 with carbon monoxide yields the ethenediolate complex 4 via addition, while with azobenzene reduction of the N-N double bond and release of hydrogen were observed, affording a heteroleptic strontium complex with a radical azobenzenyl ligand (5). The terminal alkyne is deprotonated by the hydride moiety to give the acetylide complex 6.