Crystal structures of the (η:η-cyclo-octa-1,5-diene)(η-toluene)-iridium(I) cation and μ-chlorido-iridium(III) complexes of 2-(phosphinito)- and 2-(phosphinometh-yl)anthra-quinone ligands.

When reacted in dry, degassed toluene, [Ir(COD)Cl] (COD = cyclo-octa-1,5-diene) and 2 equivalents of 2-(di--butyl-phosphinito)anthra-quinone (POAQH) were found to form a unique tri-iridium compound consisting of one monoanionic dinuclear tri-μ-chlorido complex bearing one bidentate POAQ ligand per iridium, which was charge-balanced by an outer sphere [Ir(toluene)(COD)] ion, the structure of which has not previously been reported. This product, which is a toluene solvate, namely, (η:η-cyclo-octa-1,5-diene)(η-toluene)-iridium(I) tri-μ-chlorido-bis-({3-[(di--butyl-phosphan-yl)-oxy]-9,10-dioxoanthracen-2-yl}hydridoiridium(III)) toluene monosolvate, [Ir(CH)(CH)][IrH(CHOP)Cl]·CH or [Ir(toluene)(COD)]Ir(κ-,-POAQ)(H)]·toluene, formed as small orange platelets at room temperature, crystallizing in the triclinic space group . The cation and anion are linked weak C-H⋯O inter-actions. The stronger inter-molecular attractions are likely the offset parallel π-π inter-actions, which occur between the toluene ligands of pairs of inverted cations and between pairs of inverted anthra-quinone moieties, the latter of which are capped by toluene solvate mol-ecules, making for π-stacks of four mol-ecules each. The related ligand, 2-(di--butyl-phosphinometh-yl)-anthra-quinone (PCAQH), did not form crystals suitable for X-ray diffraction under analogous reaction conditions. However, when the reaction was conducted in chloro-form, yellow needles readily formed following addition of 1 atm of carbon monoxide. Diffraction studies revealed a neutral, dinuclear, di-μ-chlorido complex, di-μ-chlorido-bis-(carbon-yl{3-[(di--butyl-phosphan-yl)-oxy]-9,10-dioxoanthracen-2-yl}hydridoiridium(I)), [IrH(CHOP)Cl(CO)] or [Ir(κ-,-PCAQ)(H)(CO)(μ-Cl)], IrCHClOP, again crystallizing in space group . Offset parallel π-π inter-actions between anthra-quinone groups of adjacent mol-ecules link the mol-ecules in one dimension.