Intercluster Compound between a Tetrakis{triphenylphosphinegold(I)}oxonium Cation and a Keggin Polyoxometalate (POM): Formation during the Course of Carboxylate Elimination of a Monomeric Triphenylphosphinegold(I) Carboxylate in the Presence of POMs

Abstract

The preparation and structural characterization of a novel intercluster compound, [{Au(PPh(3))}(4)(μ(4)-O)](3)[α-PW(12)O(40)](2)·4EtOH (1), constructed between a tetrakis{triphenylphosphinegold(I)}oxonium cation and a saturated α-Keggin polyoxometalate (POM) are described. The tetragold(I) cluster oxonium cation was formed during the course of carboxylate elimination of a monomeric phosphinegold(I) carboxylate complex, i.e., [Au((R,S)-pyrrld)(PPh(3))] [(R,S)-Hpyrrld = (R,S)-2-pyrrolidone-5-carboxylic acid], in the presence of the free acid form of a Keggin POM, H(3)[α-PW(12)O(40)]·7H(2)O. The liquid-liquid diffusion between the upper water/EtOH phase containing the Keggin POM and the lower CH(2)Cl(2) phase containing the monomeric gold(I) complex gave a pure crystalline sample of 1 in good yield (42.1%, 0.242 g scale). Complex 1 was formed by ionic interaction between the tetragold(I) cluster cation and the Keggin POM anion. As a matter of fact, the POM anion in 1 can be exchanged with the BF(4)(-) anion using an anion-exchange resin (Amberlyst A-27) in BF(4)(-) form. By using other Keggin POMs, such as H(4)[α-SiW(12)O(40)]·10H(2)O and H(3)[α-PMo(12)O(40)]·14H(2)O, the same tetragold(I) cluster cation was also formed, i.e., in the forms of [{Au(PPh(3))}(4)(μ(4)-O)](2)[α-SiW(12)O(40)]·2H(2)O (2) and [{Au(PPh(3))}(4)(μ(4)-O)](3)[α-PMo(12)O(40)](2)·3EtOH (3). Compounds 1-3, as dimethyl sulfoxide-soluble, EtOH- and Et(2)O-insoluble dark-yellowish white solids, were characterized by complete elemental analysis, thermogravimetric and differential thermal analyses, Fourier transform IR, X-ray crystallography, and solid-state (CPMAS (31)P and (29)Si) and solution ((31)P{(1)H} and (1)H) NMR spectroscopy. The molecular structures of 1 and 2 were successfully determined. The tetragold(I) cluster cation was composed of four PPh(3)Au(I) units bridged by a central μ(4)-oxygen atom in the geometry of a trigonal pyramid or distorted tetrahedron.

Zn Electrochemistry in 1‐Ethyl‐3‐Methylimidazolium and N‐Butyl‐N‐Methylpyrrolidinium Dicyanamides: Promising New Rechargeable Zn Battery Electrolytes

“…Recently, we unexpectedly discovered a clusterization of mononuclear phosphanegold(I) cations, [Au(PR 3 )] + during the course of carboxylate elimination from a monomeric phosphanegold(I) carboxylate, [Au( RS ‐pyrrld)(PPh 3 )] ( RS ‐Hpyrrld = RS ‐2‐pyrrolidone‐5‐carboxylic acid)3 in the presence of free‐acid form of Keggin POM, H 3 [α‐PW 12 O 40 ] · 7H 2 O 4a. This reaction resulted in the formation of tetrakis{triphenylphosphanegold(I)}oxonium cations, [{Au(PPh 3 )} 4 (μ 4 ‐O)] 2+ as countercations of POM anions.…”

“…In fact, the previously described heptagold(I) cluster cation has been synthesized only by the POM‐mediated clusterization method 4c. Also, the POM anion as a counterion of tetragold(I) cluster cation can be exchanged with the BF 4 – anion, resulting in a formation of the previously reported tetragold(I) cluster cation by the Schmidbaur research group 4a…”

When Gold Cations Meet Polyoxometalates

“…It is essential to acknowledge that all their syntheses are rationalized and associated to SICCs fully characterized by elemental analysis (EA), thermogravimetric and differential thermal analysis (DTA), infrared spectroscopy (FTIR), solid‐state and liquid NMR spectroscopies and finally SC‐XRD. Their first SICC was unexpectedly synthesized during the course of an acid‐base reaction between a free acid form of POM and a gold(I) phosphane complex bearing a labile pyrrolidinone‐carboxylate ligand . Thus following this methodology, solutions of 12, 8, or 7 equiv of triphenylphosphane gold(I) ( S , R )‐2‐pyrrolidinone‐5‐carboxylate [Au(PPh 3 )( R , S )‐pyrrld)] or tri( ortho ‐tolyl)phosphane) gold(I) ( S , R )‐2‐pyrrolidinone‐5‐carboxylate [Au(P( o ‐tol) 3 )( R , S )‐pyrrld)] dissolved in DCM and layered with mixtures of ethanol‐water containing 2 equiv of [H] + 3 [α‐PW 12 O 40 ] 3− , 2 equiv of [H] + 3 [PMo 12 O 40 ] 3− , 1 equiv of [H] + 4 [α‐SiW 12 O 40 ] 4− , 1 equiv of [H] + 5 [α‐AlW 12 O 40 ] 5− or 1 equiv of [H] + 5 [α‐BW 12 O 40 ] 5− afford the SICCs [{Au(PPh 3 )} 4 ( μ 4 ‐O)] 2+ 3 [α‐PW 12 O 40 ] 3− 2 ( 16 ), [{Au(P( o ‐tol) 3 )} 4 ( μ 4 ‐O)] 2+ 3 [α‐PW 12 O 40 ] 3− 2 ( 17 ), [{Au(PPh 3 )} 4 ( μ 4 ‐O)] 2+ 3 [PMo 12 O 40 ] 3− 2 ( 18 ), [{Au(P( o ‐tol) 3 )} 4 ( μ 4 ‐O)] 2+ 3 [PMo 12 O 40 ] 3− 2 ( 19 ), [{Au(PPh 3 )} 4 ( μ 4 ‐O)] 2+ 2 [α‐SiW 12 O 40 ] 4− ( 20 ), [{Au(P( o ‐tol) 3 )} 4 ( μ 4 ‐O)] 2+ 2 [α‐SiW 12 O 40 ] 4− ( 21 ), [{Au(PPh 3 )} 4 ( μ 4 ‐O)] 2+ [α‐AlW 12 O 40 {Au(PPh 3 )} 3 ] 2− ( 22 ), or [{Au(PPh 3 )} 4 ( μ 4 ‐O)] 2+ [α‐BW 12 O 40 {Au(PPh 3 )} 3 ] 2− ( 23 ) as crystals with approximately 50 % yields (Figure ) …”

An inorganic-organic hybrid supramolecular complex (H3O)4[(CoC14H12N2O10)1.5(SiW12O40)]·2H2O: synthesis, structure, properties, and application to catalytic elimination methanol

“…The electrons have been tied with the polyanion surface, increasing the non-radiative transitions, so that the fluorescence intensity of the complex is lower than H 4 SiW 12 O 40 . The silicotungstate anion structure is stabilized when [SiW 12 O 40 ] 4− coordinates with 2,3-pyridine dicarboxylic acid and Co 2+ , reducing the electronic transition energy, causing the red shift.…”

“…Depending on the location of N and O, heteropolyacid and metal ions could coordinate with pyridine dicarboxylic acid by coordination, H-bonding or π-π stacking to form different structures. Therefore, they are valuable building blocks for inorganic-organic complex engineering [12][13][14].…”