Pyrazolyl-bridged iridium dimers. 8. Two-center, electrophilic addition of activated acetylenes to bis(cycloocta-1,5-diene)bis(.mu.-pyrazolyl)diiridium(I) leading to a diiridacyclobutene configuration: regular, parallel coordination of methyl propiolate

Dynamic Behavior, Redistribution Reactions, and Intermetallic Distances of Dinuclear Bis(μ-pyrazolato)rhodium(I) Complexes

“…While an extensive study on the dinuclear bis(μ-pyrazolato)iridium(I) complexes (including oxidative-addition reactions, kinetic, electrochemistry, photochemistry, and theoretical studies 12 ) has been carried out, the chemistry of the related (μ-pyrazolato)rhodium(I) complexes has been concentrated on substitution, 1a,b some oxidative-addition, 1c,d, and hydroformylation reactions . Both rhodium and iridium systems have π-acidic ancillary ligands, including diolefins, carbon monoxide, and tertiary phosphines.…”

Pyrazolyl-Bridged Iridium Dimers. 17.1 Tetrakis(alkene)diiridium(I) Complexes: [Ir(η2-C2H4)2(μ-Cl)]2 as a Precursor to [Ir(η2-C2H4)2(μ-pz)]2. Stereochemically Nonrigid Behavior of the Analogue [Ir(η2-C2H4)(η2-C2F4)(μ-Cl)]2

“…We suggest that this comparison supports the proposition that the origin of the unusual properties of the COD dimer 3,6 is indeed inhibition of intermetallic approach through steric opposition exerted by the requirements of the two diolefin carbocycles. This effect is avoided in a related metal−metal bonded diiridium(II) perfluorobut-2-yne adduct (d 7 2 : Ir−Ir = 2.623 Å) only by , severe buckling of the COD frameworks away from typical geometry. Although a bridge-substituted (μ-Me 2 pz) dirhodium analogue of 2 was recently structurally characterized (nonbonding Rh 2 separation 3.096 Å: the shortest such approach yet observed 9 ) and facile substitution of terminal ligands in the dirhodium congener 8 [Rh(η 2 -C 2 H 4 ) 2 (μ-pz)] 2 of 2 has been shown to offer a useful synthetic strategy, no binuclear rhodium(II) adducts that are analogues of 3 appear to have yet been prepared .…”