A trinuclear Au^I complex (3A) was synthesized and fully characterized relative to mononuclear (1A) and dinuclear (2A) complexes. The single-crystal X-ray diffraction analyses show that the Au^I-centered vectors in each of the Au^I complexes (1A–3A) are all in a slightly distorted linear configuration, in which the Au^I center is diagonally coordinated by one Cl^– and one phosphine ligand. In 3A each P–Au–Cl vector is radially attached to the core of 1-(thiazol-2′-yl)imidazolyl, which does not allow the short contact between the Au atoms to develop an aurophilic Au^I–Au^I interaction. Every P–Au–Cl moiety in 3A is different to each other in terms of Au–P and Au–Cl bond lengths, P–Au–Cl bond angles, and P–Au–Cl configurable orientation owing to the different coordinating ability of the involved phosphines. When 1A–3A were employed as the precatalysts for the hydration of phenylacetylene in aqueous methanol media without the involvement of any auxiliary additive, and at the same benchmark Au concentration, the reaction over 3A proceeded selectively according to Markovnikov's rule with the highest yield of acetophenone relative to those over 2A and 1A. This indicates that the catalytic performance of 3A is the outcome of the synergetic effect of the three different R₃P–Au centers, in which each R₃P–Au site plays an individual role in activating the substrate molecule.

The stable ionic Pd^II complexes 1A–4A were synthesized through the complexation of PdCl₂(MeCN)₂ with the phosphane-functionalized ionic liquids (FILs) 1–4 with π-acceptor character. Single-crystal X-ray diffraction analyses showed that 1A–4A were all composed of Pd^II-centred square-planar cations and triflate (OTf^–, CF₃SO₃^–) counteranions. The complex cations in 1A–3A possessed structural similarity to trans-PdCl₂(PPh₃)₂. The cation in 4A was a new Pd^II-centered planar complex ligated by the phosphane–carbon anion–carbene (PCC) pincer in a tripodal manner. The stabilities of 1A–4A were improved due to the intensive π-backbonding interaction between the Pd and P atoms. When complexes 1A–4A were used as precatalysts for homogeneous carbonylative Sonogashira coupling of PhI with phenylacetylene free of CuI, 1A–3A exhibited excellent catalytic behaviour with a TON of up to 1700 at a CO pressure of 0.5 MPa and moderate temperature of 100 °C, whereas 4A exhibited poor activity towards the transformation of PhI due to the high stability of 4A. The recycling experiments of 3A in [Bpy]BF₄ (as a solvent) indicated that 3A could be recycled for 5 runs with neither activity loss nor metal leaching into the organic phase. Complex 3A also proved to be a general precatalyst for the carbonylative Sonogashira couplings of a wide range of aryl iodides with phenylacetylene. The selectivity of the desired carbonylation product depended more on electronic effects than the steric effects of the substituents of the aryl iodides.

A novel ionic complex, bis[1-butyl-2-(diphenylphosphanyl)-3-methylimidazolium]tetrachloridoruthenium(III) hexafluorophosphate (2), has been synthesized and fully characterized. The single-crystal X-ray diffraction analysis showed that 2 is composed of an Ru complex cation and PF₆^– anion. The cation has a highly symmetrical Ru-centered octahedron geometry with four Cl atoms in the equatorial plane and two imidazolium-substituted phosphane ligands in the axial positions. It exhibits paramagnetism due to the presence of one unpaired electron in the phosphane-ligated low-spin Ru^III complex. Complex 2 exhibited good catalytic performance in the transfer hydrogenation of a wide range of ketones by using alcohols as hydrogen donors. Owing to its high polarity, good thermal stability, and insensitivity to moisture and oxygen, complex 2 could be used in six catalytic cycles in the transfer hydrogenation of acetophenone without any obvious loss of activity.

The functionalized ionic liquids (ILs) of N-n-dodecyl pyridinium vanadate (1), N-(propyl-1-sulfonic acid) pyridinium tetrafluoroborate (2), and 4-(propanoate-2,2,6,6,-tetramethylpiperidine-1-oxyl) pyridinium tetrafluoroborate (5) were synthesized. The mixture of 1, 2, and 5 in [Bpy]BF₄ yielded the compatible IL compositions (ILCs) as a homogenous mixture, which proved to be an efficient catalytic system for oxidation of a wide range of alcohols using H₂O₂. With the aid of 2 and 5, 1 in [Bpy]BF₄ could easily be recovered and reused for at least six runs without a loss in activity. UV/Vis spectroscopic analysis indicated that the role of 2 was to promote the formation of the active peroxo V^V species, which is responsible for substrate activation, and the role of 5 was to oxidize the low-valent vanadium(II–IV) species to regenerate 1.