Synthesis and Characterization of Hydridoirida-β-diketones Formed by the Reaction of [{Ir(Cod)Cl}₂] (Cod = 1,5-cyclooctadiene) witho-(Diphenylphosphino)benzaldehyde

Abstract

[{Ir(Cod)Cl}2] (Cod = 1,5-cyclooctadiene) reacts with o-(diphenylphosphino)benzaldehyde (PPh2(o-C6H4CHO)) (Ir:P = 1:2) in methanol to give the hydridoirida-β-diketone complex [IrH{(PPh2(o-C6H4CO))2H}Cl] (1). The reactivity of 1 to afford neutral and cationic hydridoirida-β-diketones is also discussed

Synthesis and Reactivity of New Mono‐ and Dinuclear Hydridoirida‐β‐diketones – The Formation and Characterization of a Dinuclear Tris‐μ‐acyliridium(III) Complex

“…Both bridging Ir-Cl distances in 5 are equal within experimental error and are, as expected, significantly longer [2.539(3) Å] than the terminal Ir-Cl distance in 1 [2.485(3) Å]. [8] As far as we are aware, there is only one precedent of a dinuclear iridium complex containing a single chlorine bridge, which is trans to an SiR 2 RЈ group. [14] The Ir-Cl distances in 5 are shorter than those found in this previously reported complex and this difference may reflect the expected stronger structural trans influence of SiR 3 groups than of hydrido ligands.…”

“…The O···O distances and O-H-O angles are in accordance with a strong enolic character for the hydrogen bond and agree with those reported for other irida-β-diketones. [8,9] In keeping with the crystal structure, the 31 P{ 1 H} NMR spectra of 5 and 6 show two singlets at δ = 30.7 and 18.3 ppm, respectively, at 203 K, and in the 13 C{ 1 H} NMR spectra two doublets at δ = 257.6 (J P,C = 101 Hz) and 255.6 ppm (J P,C = 103 Hz) are observed. The 1 H NMR spectra contain a triplet at δ = -23.17 (J P,H = 14.6) ppm and a singlet at δ = 22.66 ppm.…”

“…The 1 H NMR spectra show the hydride resonances as triplets due to a J P,H coupling of about 12 Hz, which agrees with the hydride being cis to both phosphane ligands, and sharp, low-field singlets at δ = 22.72 ppm for 2 and 22.69 ppm for 3, which support the presence of fairly strong O···H···O hydrogen bonds and the existence of irida-β-diketones containing a formally tetradentate PCCP ligand. [8,9] Complex 2 behaves as nonelectrolyte in acetone solution, whereas acetone solutions of 3 show conductivity values expected for 1:1 electrolytes. [13] (6)], which contain a cationic dinuclear species with a single chlorine atom bridging two hydridoirida-β-diketone fragments (see i in Scheme 3).…”

“…Both the ν(Ir-H) absorptions (2224 cm -1 for 2 and 2264 cm -1 for 3) at rather high wavenumber and the hydride resonances (δ = -24.24 ppm for 2 and -25.89 ppm for 3) at rather high field are in accordance with a hydrido ligand being trans to the bonded oxygen atom of the anion. [8] The σ-donor strength of O-coordinated anions is among the smallest and this is reflected in the trans effect. [12] The NMR spectroscopic data for both 2 and 3 indicate the presence of two equivalent acylphosphane fragments.…”

“…[7] The reaction of [Ir(Cl)(H)-{PPh 2 (o-C 6 H 4 CO)}(cod)] (cod = 1,5-cyclooctadiene) with PPh 2 (o-C 6 H 4 CHO) in protic solvents has allowed the preparation of the first hydridoirida-β-diketone [IrH{[PPh 2 (o-C 6 H 4 CO)] 2 H}Cl]. [8] Cationic mononuclear hydridoirida-β- [9] We report now on the preparation of new hydridoirida-β-diketones, including novel dinuclear species, and on the deprotonation of the latter to afford a dinuclear tris-µ-acyliridium(III) complex.…”