Unsymmetric Ir and RhIr Dinuclear Complexes Supported by a Linear Tetraphosphine -dpmppp, Showing High Reactivity for O, H, and HCl.

Unsymmetric dinuclear Ir(I) complexes, [IrCl(L)(-dpmppp)] (L = XylNC (), BuNC (), CO ()), were synthesized using -PhPCHP(Ph)(CH)P(Ph)CHPPh (-dpmppp), which supports - (M) and (M) metal sites, and exhibited high reactivity for O, H, and HCl. The IrRh heterodinuclear complexes, [MMCl(L)(-dpmppp)] () (MM = IrRh, RhIr; L = XylNC, CO ( = , )), were also synthesized and used together with the Rh complexes () to elucidate the role of each metal site. For the reactions of O, and showed higher reactivity than those of and , giving η-peroxide complexes [{MCl}{M(η-O)(XylNC)}(-dpmppp)] (, ), from which O would not dissociate.

Unsymmetric Dinuclear Rh and RhRh Complexes Supported by Tetraphosphine Ligands and Their Reactivity of Oxidative Protonation and Reductive Dechlorination.

Two linear tetradentate phosphine ligands, -PhPCHP(Ph)CHCHP(Ph)CHPPh ( = CH (-dpmppp), NBn (-dpmppmNBn; Bn = benzyl)) were utilized to synthesize unsymmetrical dinuclear Rh complexes, [RhCl(-dpmppp)(L)] (L = XylNC (), CO ()) and [RhCl(-dpmppmNBn)(L)] (L = XylNC (), CO ()), where electron-deficient Rh → Rh centers with 30 valence electrons are supported by a tetraphosphine in an unusual /- coordination mode. The Rh dimers of - were treated with HCl under air to afford the Rh → Rh dimers with 32 e, [RhCl(-dpmppp)(L)] (L = XylNC (), CO ()) and [RhCl(-dpmppmNBn)(L)] (L = XylNC (), CO ()), via intermediate hydride complexes, [{RhCl(μ-H)RhCl(L)}(-dpmppp)] (L = XylNC (), CO ()) and [{RhCl(μ-H)RhCl(L)}(-dpmppmNBn)] (L = XylNC (), CO ()), and [{Rh(H)Cl(μ-Cl)Rh(L)}-dpmppp)] (L = XylNC (), CO ()) and [{Rh(H)Cl(μ-Cl)Rh(L)}-dpmppmNBn)] (L = XylNC (), CO ()). The hydride intermediates and were monitored under nitrogen by H{P} and P{H} NMR techniques to reveal two reaction pathways depending on the terminal auxiliary ligand L.