Formation and Site-Selective Reactivity of a Nonsymmetric Dinuclear Iridium BisMETAMORPhos Complex

A flexible
di­(sulfonamidophosphine) ligand (1H2, Ph2PNHS­(O)2NHPPh2) was synthesized from commercially available
sulfamide and chlorodiphenylphosphine. Coordination of this new bisMETAMORPhos 1H2 with [Ir­(Cp*)­Cl­(μ-Cl)]2 instantly led to the formation of the P,P-coordinated bimetallic
complex 2 [Ir­(Cp*)­Cl­(κ1-P1; κ1-P2-1H2)­Ir­(Cp*)­Cl]. Reaction of 2 using excess NaOAc led to the formation of nonsymmetric
homodinuclear complex 3 [Ir­(Cp*)­Cl­(κ2-P,O; κ3-P,N,C; μ-1)­Ir­(Cp*)], which contains two distinctly different IrIII centers, with a fac-P,N,C and a fac-P,O,Cl coordination environment.
The ligand is overall trisanionic due to additional intramolecular
C–H activation of a flanking phenyl ring. Complex 3 reacts selectively at the Ir­(P,O,Cl) center with a single equivalent of HCl or H2 to generate complexes 4 and 5,
respectively. These complexes are generated via heterolytic cleavage
of the H–Cl or H–H bond, which reprotonates the ligand
showing its bifunctional applicability. The Ir–C bond is found
to be inert under these conditions.

一种灵活的（二）磺酰胺基膦配体（1H2，Ph2PNHS(O)2NHPPh2）由市售的磺酰胺和氯二苯基膦合成。该新合成的双金属配体1H2与[Ir(Cp*)Cl(μ-Cl)]2的配位作用迅速导致P,P-配位的双金属配合物2 [Ir(Cp*)Cl(κ1-P1; κ1-P2-1H2)-Ir(Cp*)Cl]的形成。将过量的NaOAc与2反应，可生成非对称的同核配合物3 [Ir(Cp*)Cl(κ2-P,O; κ3-P,N,C; μ-1)-Ir(Cp*)]，其中包含两个具有不同配位环境的明显不同的IrIII中心，分别为fac-P,N,C和fac-P,O,Cl。由于邻位苯环的C-H键内分子活化作用，该配体总体上呈现三阴离子性质。配合物3在Ir(P,O,Cl)中心与单个等量的HCl或H2发生选择性反应，分别生成配合物4和5。这些配合物通过H-Cl或H-H键的异裂生成，该过程使配体重新质子化，显示出其双功能应用性。在这些条件下，Ir-C键被发现是惰性的。