ic502875y_si_005.cif (869.69 kB)
Ir(2-Phenylpyridine)2(benzene-1,2-dithiolate) Anion as a Diastereoselective Metalloligand and Nucleophile: Stereoelectronic Effect, Spectroscopy, and Computational Study of the Methylated and Aurated Complexes and their Oxygenation Products
dataset
posted on 2015-03-02, 00:00 authored by Van Ha Nguyen, Rebecca Shu Hui Khoo, John H. K. YipThe
anionic complex [Ir(2-phenylpyridine)2(benzene-1,2-dithiolate)]− ([IrSS]−) is a nucleophile
and metalloligand that reacts with methyl iodide and AuPR3+ (R = Ph or Et) to form S-methylated complexes (thiother–thiolate
and dithiother complexes) and S-aurated complexes, respectively. The
reactions are completely diastereselective, producing only the enantiomers
ΛS and ΔR or ΛSS and ΔRR. The diastereoselectivity
is stereoelectronically controlled by the orientation of the highest
occupied molecular orbital (HOMO) of [IrSS]− arising from filled dπ–pπ antibonding interactions,
and the chirality of the iridium ion. Methylation or auration removes
the high-energy lone pair of the thiolate S atom, leading to low-lying
HOMOs composed mainly of the Ir d-orbital and the 2-phenylpyridine
π (ppyπ) orbital. The methylated and aurated complexes
can be oxidized by H2O2 or peracid to give sulfinate–thiother,
disulfoxide, and sulfinate–sulfoxide complexes, and the oxygenation
further stabilizes the HOMO. All the complexes are luminescent, and
their electronic spectra are interpreted with the aid of time-dependent
density functional theory calculations. The thiother–thiolate
complex exhibits ligand(S)-to-ligand(π* of ppy)-charge-transfer/metal-to-ligand-charge-transfer
absorption (LLCT/MLCT) and a relatively low-energy 3LLCT/MLCT
emission, while the other complexes display 3ππ*/MLCT
emissions.