Syntheses and crystal structures of [IrIII{C(CHCO2Et)(dppm)2-κ4P,C,C′,P′}ClH]Cl·2.75CH2Cl2 and its derivatives, [IrIII{C(CHCO2Et)(dppm)2-κ4P,C,C′,P′}(CH2CO2Et)Cl]Cl·CH3OH·0.5H2O, [IrIII{C(CHCO2Et)(dppm)2-κ4P,C,C′,P′}Cl2]Cl·CH3OH·2H2O and [IrIII{C(CHCO2Et)(dppm)2-κ4P,C,C′,P′}(CH2CO2Et)(CO)]Cl2·2CH2Cl2·1.5H2O

Abstract

The common feature of the four iridium(III) salt complexes, (bis{[(diphenylphosphanyl)methyl]diphenylphosphanylidene}(ethoxyoxoethanylidene)methane-κ4P,C,C′,P′)chloridohydridoiridium(III) chloride methylene chloride 2.75-solvate (4), (bis{[(diphenylphosphanyl)methyl]diphenylphosphanylidene}(ethoxyoxoethanylidene)methane-κ4P,C,C′,P′)chlorido(ethoxyoxoethanido)iridium(III) chloride–methanol–water (1/1/0.5) (5), (bis{[(diphenylphosphanyl)methyl]diphenylphosphanylidene}(ethoxyoxoethanylidene)methane-κ4P,C,C′,P′)dichloridoiridium(III) chloride–methanol–water (1/1/2) (6) and (bis{[(diphenylphosphanyl)methyl]diphenylphosphanylidene}(ethoxyoxoethanylidene)methane-κ4P,C,C′,P′)carbonyl(ethoxyoxoethanide)iridium(III) dichloride–methylene chloride–water (1/2/1.5) (7) or in terms of their formulae [Ir(C55H50O2P4)ClH]Cl·2.75CH2Cl2 (4), [Ir(C4H7O2)(C55H50O2P4)Cl]Cl·CH3OH·0.5H2O (5), [Ir(C55H50O2P4)Cl2]Cl·CH3OH·2H2O (6) and [Ir(C4H7O2)(C55H50O2P4)(CO)]Cl2·2CH2Cl2·1.5H2O (7) is a central IrIII atom coordinated in a distorted octahedral fashion by a PCCP ligand system and two additional residues, such as chlorides, a hydride, a carbonyl or an alkyl unit. Thereby, the PCP pincer ligand system and the residue trans to the carbodiphosphorane (CDP) C atom surround the iridium(III) transition metal in the equatorial plane under the formation of two five-membered dissimilar chelate rings [C—CCDP—P (4, 5, 6 and 7) for the first ring: 120.2 (3), 121.9 (5), 111.2 (3) and 121.7 (2) °; for the second ring: 112.1 (3), 113.5 (5), 120.5 (3) and 108.3 (2)°]. A cyclopropane-like heterocycle is positioned approximately orthogonal (84.21–88.85°) to the equatorial plane, including an alkylidene bridge connecting the IrIII atom and the coordinating CDP atom of the PCP subunit. In general, the neutral PCCP ligand system coordinates the metal in a tetradentate way via three Lewis acid/base bonds and by an alkylidene unit presenting strengthened interactions. In all the crystal structures, (disordered) solvent molecules are present in the voids of the packed molecules that interact with the positively charged complex and its chloride counter-ion(s) through weak hydrogen bonding.

Keywords

• carbodiphosphorane (CDP)
• PCP pincer
• diazo compounds
• cycloaddition
• iridium(III)
• C–C coupling reaction
• non-innocent behaviour
• alkylidene bridge
• carbene intermediate
• insertion reaction
• crystal structure