Unprecedented pentadenticity of the HB(3-Phpz)(3) (= Tp(Ph)) ligand

Previously unobserved pentadentate coordination of a tris(pyrazolyl)borate ligand has been ascertained in the compound Ir[kappa(5)(N,N',N ",C-Ph,C-Ph' )-Tp(Ph)](eta(2)-C2H4) (Tp(Ph) = hydridotris(3-phenylpyrazolyl)borate] that forms by thermal activation of a mixture of [IrCl(coe)(2)](2) (coe = cyclo octene) with TlTp(Ph) and ethene, through the intermediacy of Ir[kappa(4)(N ,N',N ",C-Ph)-Tp(Ph)](Et)(eta(2)-C2H4).