Zr−Ir hydrido complexes with ansa-(cyclopentadienyl)-
(amide) as the supporting ligand in the zirconium fragment, e.g.,
(L1ZrR)(Cp*Ir)(μ-H)3 [L1 = Me2Si(η5-C5Me4)(NtBu), R = Cl (5), Ph
(7), Me (10), alkyl, and aryl] were designed, synthesized, and isolated
as tractable early−late heterodinuclear complexes. Despite the
presence of the three supporting hydride ligands, Zr−Ir distances in
the crystal structures of 5, alkyl, and aryl complexes [2.74−2.76 Å]
were slightly longer than the sum of the element radii of Zr and Ir
[2.719 Å]. These hydrocarbyl complexes displayed the thermolytic
C−H activation of a variety of aromatic compounds and several
organometallic compounds. Also, the substrate scope and limitation in
the Zr−Ir system were studied. The regiochemical outcomes during
the C−H activation of pyridine derivatives and methoxyarenes
suggested the in situ generation of a Lewis acidic active intermediate, i.e., (L1Zr)(Cp*IrH2) (III). The existence of III and
relevant σ-complex intermediates {L1Zr(η2-R−H)}(Cp*IrH2) (IIR) (R = Me, Ph) in the ligand exchange was demonstrated by
the direct isolation of a Et3PO-adduct of III (39b) from 7 and kinetic studies. The structure of the direct Zr−Ir bonds in IIPh,
IIMe, III, and 39b were probed using computational studies. The unprecedented strong M−M′ interactions in the early−late
heterobimetallic (ELHB) complexes have been proposed herein.
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