Abstract
The dinuclear complexes [RhCl(L)~2~]~2~ (1, 2) with L = 1‐isopropyl‐(2__S__,5__S__)‐2,5‐dimethylphospholane (Isophos) and (2__S__,5__S__)‐2,5‐dimethyl‐1‐phenylphospholane (Phephos), respectively, prepared from [RhCl(C~8~H~14~)~2~]~2~ and four equivalents of L, react with Lewis bases such as L, CO, ethene and diphenylacetylene by cleavage of the chloride bridges. Mononuclear compounds of the general composition [RhCl(L)~3~] (3, 4) and trans‐[RhCl(L′)(L)~2~] (5−9; L′ = CO, C~2~H~4~, C~2~Ph~2~) were obtained, of which 4 (L = Phephos) and 8 (L′ = C~2~H~4~; L = Phephos) are in equilibrium with the precursors. Oxidative addition of H~2~ to 1 (L = Isophos) and [RhCl(P__i__Pr~2~Ph)~2~]~2~ (10) affords the mononuclear dihydrido complexes [RhH~2~Cl(L)~2~] (13) and [RhH~2~Cl(P__i__Pr~2~Ph)~2~] (14), respectively, via the unsymmetrical compounds [RhH~2~(L)~2~(μ‐Cl)~2~Rh(L)~2~] (11) and [RhH~2~(P__i__Pr~2~Ph)~2~(μ‐Cl)~2~Rh(P__i__Pr~2~Ph)~2~] (12) as intermediates. These intermediates can be isolated by treatment of 13 and 14 with one half equivalent of 1 or 10, respectively. The hydrogenation of the η^3^‐allyl and η^3^‐benzyl complexes [(η^3^‐2‐RC~3~H~4~)Rh(L)~2~] (16−18) and [(η^3^‐CH~2~Ph)Rh(L)~2~] (19, 20), which were prepared from 1 or 2 and the corresponding Grignard reagent, leads to the dinuclear Rh^III^Rh^I^ products [RhH~2~(L)~2~(μ‐H)~2~Rh(L)~2~] (21, 22), which are structurally related to the dichloro(dihydrido) derivatives 11 and 12. Compound 21 (L = Isophos) reacts with CO to give trans‐[RhH(CO)(L)~2~] (23). While treatment of 1 with phenylacetylene yields the vinylidene complex trans‐[RhCl(=C=CHPh)(Isophos)~2~] (26), via η^2^‐alkyne and alkynyl(hydrido) intermediates, the reaction of 2 with PhC≡CH affords the labile enyne compound trans‐[RhCl{η^2^‐(E)‐PhC≡CCH=CHPh}(Phephos)~2~] (27). Reaction of 27 with CO gives 6 and the free enyne. The carbene complexes trans‐[RhCl(=CPh~2~)(L)~2~] (30, 31), obtained from trans‐[RhCl(=CPh~2~)(Sb__i__Pr~3~)~2~] (29) and L, react with ethene not by olefin metathesis but by formation of the isomeric olefins Ph~2~C=CHCH~3~ (32) and CH~2~=CHCHPh~2~ (33) in different ratios. With iridium as the metal center, carbonyl, dihydrido, and dihydrido(carbonyl) compounds with [IrCl(Isophos)~2~] as the building block have been prepared. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)