Syntheses and crystal structures of [Ir III {C(CHCO 2 Et)(dppm) 2 -κ 4 P , C , C ', P '}ClH]Cl·2.75CH 2 Cl 2 and its derivatives, [Ir III {C(CHCO 2 Et)(dppm) 2 -κ 4 P , C , C ', P '}(CH 2 CO 2 Et)Cl]Cl·CH 3 OH·0.5H 2 O, [Ir III {C(CHCO 2 Et)(dppm) 2 -κ 4 P , C , C ', P '}Cl 2 ]Cl·CH 3 OH·2H 2 O and [Ir III {C(CHCO 2 Et)(dppm) 2 -κ 4 P , C , C ', P '}(CH 2 CO 2 Et)(CO)]Cl 2 ·2CH 2 Cl 2 ·1.5H 2 O

The common feature of the four iridium(III) salt complexes, (bis-{[(di-phenyl-phosphan-yl)meth-yl]di-phenyl-phosphanyl-idene}(eth-oxy-oxoethanyl-idene)methane-κ , , ', ')chlorido-hydridoiridium(III) chloride methyl-ene chloride 2.75-solvate ( ), (bis-{[(di-phenyl-phosphan-yl)meth-yl]di-phenyl-phosphanyl-idene}(eth-oxy-oxoethanyl-idene)methane-κ , , ', ')chlorido-(eth-oxy-oxoethanido)iridium(III) chloride-methanol-water (1/1/0.5) ( ), (bis-{[(di-phenyl-phosphan-yl)meth-yl]di-phenyl-phosphanyl-idene}(eth-oxy-oxoethanyl-idene)methane-κ , , ', ')di-chlorido-iridium(III) chloride-methanol-water (1/1/2) ( ) and (bis-{[(di-phenyl-phosphan-yl)meth-yl]di-phenyl-phosphanyl-idene}(eth-oxy-oxoethanyl-idene)methane-κ , , ', ')carbon-yl(eth-oxy-oxoethanide)iridium(III) dichloride-meth-yl-ene chloride-water (1/2/1.5) or in terms of their formulae [Ir(C H O P )ClH]Cl·2.75CH Cl ( ), [Ir(C H O )(C H O P )Cl]Cl·CH OH·0.5H O ( ), [Ir(C H O P )Cl ]Cl·CH OH·2H O ( ) and [Ir(C H O )(C H O P )(CO)]Cl ·2CH Cl ·1.5H O ( ) is a central Ir atom coordin-ated in a distorted octa-hedral 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 to the carbodi-phospho-rane (CDP) C atom surround the iridium(III) transition metal in the equatorial plane under the formation of two five-membered dissimilar chelate rings [C-C -P ( , , and ) 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 cyclo-propane-like heterocycle is positioned approximately orthogonal (84.21-88.85°) to the equatorial plane, including an alkyl-idene bridge connecting the Ir atom and the coordinating CDP atom of the PCP subunit. In general, the neutral PCCP ligand system coordinates the metal in a tetra-dentate way via three Lewis acid/base bonds and by an alkyl-idene unit presenting strengthened inter-actions. In all the crystal structures, (disordered) solvent mol-ecules are present in the voids of the packed mol-ecules that inter-act with the positively charged complex and its chloride counter-ion(s) through weak hydrogen bonding.