A series of annular dinuclear Au(I) complexes containing diphosphine (R(2)P(CH(2))(n)()PR(2); R = Me, n = 1, dmpm; R = Me, n = 2, dmpe; R = Ph, n = 1, dppm; R = Ph, n = 2, dppe) and dithiolate (dtc = S(2)CNEt(2)(-), i-mnt = S(2)C(2)(CN)(2)(2)(-)) ligands were synthesized: [Au(2)(P-P)(S-S)]X (S-S = dtc: P-P = dmpm, X = Cl, 1; P-P = dppm, X = PF(6), 2; P-P = dppe, X = PF(6), 3; P-P = PPh(3), X = PF(6), 4) and [Au(2)(P-P)(S-S)] (S-S = i-mnt: P-P = dmpm,5; P-P = dppm, 6; P-P = dmpe, 7; P-P = dppe, 8). Crystal structures of two complexes are reported. Pertinent crystallographic data: [Au(2)(dmpm)(i-mnt)] (5), space group Fdd2, with a = 19.574(3) Å, b = 48.220(11) Å, and c = 15.273(2) Å, R = 0.0542; [Au(2)(dppe)(i-mnt)] (8), space group P2(1)/n, with a = 11.793(2) Å, b = 19.607(2) Å, and c = 15.349(2) Å, R = 0.0448. Each molecule has two gold atoms bridged by a dithiolate ligand on one side and a diphosphine ligand on the other side, thus forming an eight- or nine-membered ring digold complex. The tendency of the digold(I) compounds to aggregate through an intermolecular Au-Au interaction depends on the ligands. Among the structures determined, complex 5 forms a polymeric chain and compound 8 is monomeric. Molecular aggregation also occurs in solution. Concentration-dependent absorption spectra of Au-dtc compounds suggest that an equilibrium between the monomer and dimer exists. Equilibrium constants corresponding to the intermolecular Au-Au interaction range from 38 to 137 M(-)(1) with DeltaH values of approximately 15 kcal/mol and DeltaS values of approximately -35 to approximately -46 cal/(K mol). Concentration dependence of emission spectra of annular compounds in acetonitrile also supports association in solution. Emissions at approximately 400-440 nm assignable to spin-allowed metal-centered transitions from monomeric Au(2) at lower concentrations and dimeric Au(4) at higher concentrations are observed. Compounds 1-3 and 5-8 in the glass state having spin-forbidden dithiolate ligand to gold charge transfer ((3)LMCT) transitions give emission bands at approximately 550 nm. Compound 4 has a S --> Au (3)LMCT transition at 500 nm. (31)P variable-temperature NMR experiments were performed for 1-3. The dynamic process is attributed to molecular aggregation through an intermolecular Au-Au interaction in solution. The activation energies are approximately 9 kcal/mol for 1 and 2.

Ionic gold(I) complexes with general formula of [Au(Py)2][AuCl2] and [Au(Py)2][PF6] (Py = 4-substituted pyridines) have been synthesized. Structures of five Au(I) complexes and a Ag(I) complex were determined by single crystal X-ray diffraction. Evidence for cationic aggregation of [Au(py)2][PF6] complexes in solution was obtained by conductivity measurements and by the isosbestic point observed from variable temperature UV-visible absorption spectra. All compounds were luminous in the solid state. Calculations employing density functional theory were performed to shed light on the nature of the electronic transitions. While the [Au(4-dmapy)2][AuCl2] (4-dmapy = 4-dimethylaminopyridine) and [Au(4-pic)2][AuCl2] (4-pic = 4-picoline) emissions were found to be mainly ligand in nature, their [PF6](-) counterparts involved a Au...Au-interaction imbedded in the highest occupied molecular orbital. [Au(4-dmapy)2][AuCl2] was found to be an efficient catalyst for Suzuki cross-coupling of aryl bromide and phenylboronic acid.

Under PTC/OH- (PTC = phase-transfer catalysis) conditions, the reaction of Au2(dppm)Cl2 (dppm = 1,1-bis(diphenylphosphino)methane) with [Me2S(O)NMe2]BF4 produces a greenish luminescent compound [Au2(dppm)[(CH2)2S(O)NMe2]]BF4, 1, and a colorless tetranuclear compound [Au4(dppm)(Ph2PCHPPh2)[(μ-CH)(CH2)S(O)NMe2]]BF4, 2. Both compounds 1 and 2 also can be synthesized from [Au4(dppm)(Ph2PCHPPh2)Cl3], 3, which can be produced simply by the reaction of Au2(dppm)Cl2 with OH- in the presence of a PTC. For Au2(dppe)Cl2 (dppe = 1,2-bis(diphenylphosphino)ethane) and Au2(dmpm)Cl2 (dmpm = 1,1-bis(dimethylphosphino)methane), only [Au2(dppe)[(CH2)2S(O)NMe2]]PF6, 4, and [Au2(dmpm)[(CH2)2S(O)NMe2]]BF4, 5, are obtained as the major product, respectively. Compounds 1−4 are characterized by single-crystal X-ray analyses. Two C 2-related cations of 1 are packed in a row with the intermolecular Au−Au distance (2.959 Å) shorter than the intramolecular Au−Au distance (2.984 Å). Compound 2 has one of the ylide carbon atoms bridging two gold(I) atoms. The tetragold cluster of 3 is formed by an Au−C linkage between [ClAu(μ-Ph2PCH2PPh2)Au]+ and [ClAu(μ-Ph2PCHPPh2)AuCl]-. The digold cation of 4 is a nine-membered dimetallocycle. In acetonitrile solution, dimerization of 1 and 5 through intermolecular Au−Au interaction occurs as evidenced by concentration-dependent absorption spectroscopic studies. Concentration-dependent absorption spectra of 1 and 5 suggest that equilibriums between the monomer and dimer exist with equilibrium constants of 33 ± 9 and 52 ± 7 M-1 in acetonitrile, respectively. Digold(I) compounds 1, 4, and 5 luminesce in the solid state.