Syntheses, characterization, and luminescence of Pt II-M I (M = Cu, Ag, Au) heterometallic complexes by incorporating Pt(diimine)(dithiolate) with [M2(dppm)2]2+ (dppm = Bis(diphenylphosphino)methane)

Reaction of Pt(diimine)(edt) (edt = 1,2-ethanedithiolate) with M(2)(dppm)(2)(MeCN)(2)(2+) (dppm = bis(diphenylphosphino)methane) gave heterotrinuclear complexes [PtCu(2)(edt)(mu-SH)(dppm)(3)](ClO(4)) (11) and [PtCu(2)(diimine)(2)(edt)(dppm)(2)](ClO(4))(2) (diimine = 2,2'-bpyridine (bpy), 12; 4,4'-dibutyl-2,2'-bipyridine (dbbpy), 13; phenanthroline (phen), 14; 5-bromophenanthroline (brphen), 15) when M = Cu(I). The reaction, however, afforded tetra- and trinuclear complexes [Pt(2)Ag(2)(edt)(2)(dppm)(2)](SbF(6))(2) (17) and [PtAu(2)(edt)(dppm)(2)](SbF(6))(2) (21) when M = Ag(I) and Au(I), respectively. The complexes were characterized by elemental analyses, electrospray mass spectroscopy, (1)H and (31)P NMR, IR, and UV-vis spectrometry, and X-ray crystallography for 14, 17, and 18. The Pt(II)Cu(I)(2) heterotrinuclear complexes 11-15 exhibit photoluminescence in the solid states at 298 K and in the frozen acetonitrile glasses at 77 K. It is likely that the emission originates from a ligand-to-metal charge transfer (dithiolate-to-Pt) (3)[p(S) --> d(Pt)] transition for 11 and from an admixture of (3)[d(Cu)/p(S)-pi(diimine)] transitions for 12-16. The Pt(II)(2)Ag(I)(2) heterotetranuclear complexes 17 and 18 are nonemissive in the solid states and in solutions at 298 K but show photoluminescence at 77 K. The Pt(II)Au(I)(2) heterotrinuclear complexes 19-21, however, are luminescent at room temperature in the solid state and in solution. Compounds 19 and 20 afford negative solvatochromism associated with a charge transfer from an orbital of a mixed metal/dithiolate character to a diimine pi orbital.     

Luminescent heterotrinuclear complexes with Pt(diimine)(dithiolate) and metal diphosphine as components

Reactions of Pt(diimine)(tdt) (tdt =3,4-toluenedithiolate) with [M(2)(dppm)(2)(MeCN)(2)](2+) (M = Cu(I) or Ag(I), dppm = bis(diphenylphosphino)methane) gave heterotrinuclear complexes [PtCu(2)(tdt)(mu-SH)(dppm)(3)](ClO(4)) (1) and [PtCu(2)(diimine)(2)(tdt)(dppm)(2)](ClO(4))(2) (diimine = 2,2'-bpyridine (bpy) 2; 4,4'-dimethyl-2,2'-bipyridine (dmbpy) 3; phenanthroline (phen) 4, 5-bromophenanthroline (Brphen) 5) for M = Cu(I), but [PtAg(2)(tdt)(mu-SH)(dppm)(3)](SbF(6)) (6) and [PtAg(2)(diimine)(tdt)(dppm)(2)](SbF(6))(2) (diimine = bpy 7; dmbpy 8; phen 9; Brphen 10) for M = Ag(I). While the complexes [PtAg(2)(diimine)(tdt)(dppm)(2)](SbF(6))(2) (7-10) result from linkage of Pt(diimine)(tdt) and [M(2)(dppm)(2)(MeCN)(2)](2+) by tdt sulfur donors, formation of [PtCu(2)(diimine)(2)(tdt)(dppm)(2)](ClO(4))(2) (2-5) is related to rupture of metal-ligand bonds in the metal components and recombination between the ligands and the metal atoms by self-assembly. The formation of 1 and 6 is involved not only in dissociation and recombination of the metal components, but also in disruption of C-S bonds in the dithiolate (tdt). The dithiolate tdt adopts a chelating and bridging coordination mode in anti conformation for [PtCu(2)(diimine)(2)(tdt)(dppm)(2)](ClO(4))(2) (2-5), whereas there is the syn conformation for other complexes. Compounds 1 and 6 represent sparse examples of mu-SH-bridged heterotrinuclear Pt(II)M(I)(2) complexes, in which Pt(II)-M(I) centers are bridged by dppm and sulfur donors of tdt, whereas M(I)-M(I) (M = Cu for 1; Ag for 6) centers are linked by dppm and the mu-SH donor. The (31)P NMR spectra show typical platinum satellites (J(Pt-P) = 1450-1570 Hz) for 1-6 and Ag-P coupling for Pt(II)-Ag(I) (J(Ag-P) = 350-450 Hz) complexes 6-10. All of the complexes show intense emission in the solid state and in frozen glasses at 77 K. The complexes [PtAg(2)(diimine)(tdt)(dppm)(2)](SbF(6))(2) (7-10) also afford emission in fluid acetonitrile solutions at room temperature. Solid-state emission lifetimes at room temperature are in the microsecond range. It is revealed that emission energies of the trinuclear heterometallic complexes [PtAg(2)(diimine)(tdt)(dppm)(2)](SbF(6))(2) (7-10) exhibit a remarkable blue shift (0.10-0.35 eV) relative to those of the precursor compounds Pt(diimine)(tdt). The crystal structures of 1, 2, 4, 6, 8, and 9 were determined by X-ray crystallography.     

Synthesis and Crystal Structure of a Heterotrinuclear Compound [PdCu_2(tdt)(μ-dppm)_2(MeCN)_4]-(ClO_4)_2·2/3H_2O (tdt = 3,4-Toluenedithiolate, dppm =Bis(diphenylphosphino)methane)

1 INTRODUCTION Great attention has been attracted to design novel heterometallic molecular materials with phosphorus- and sulfur-containing ligands, owing to their abundant optical and opto-electronic properties[1～4]. Self-assembly is an efficient ap- proach to obtain heterometallic assembly by the Incorporation of two different metal components[5, 6]. We are interested in investigating the reaction between Pd(diimine)(dithiolate) and metal dip- hosphine Cu2(μ-dppm)2(MeCN)42 , the fo…     

Toward rational construction of gold, gold-silver, and gold-mercury string complexes: syntheses, structures, and properties of [Au(Tab)2]2L2 (L = I and PF6), {[(Tab)2M][Au(CN)2]}2 (M = Au and Ag), and {[Hg(Tab)2][Au(CN)2]2} [Tab = 4-(trimethylammonio)benzenethiolate

The reaction of AuI with 2 equiv of TabHPF6 [TabH = 4-(trimethylammonio)benzenethiol] in the presence of excess Et3N in dimethylformamide (DMF)/MeOH afforded a binuclear gold(I) complex [Au(Tab)2]2I2.2H2O (1). Anion exchange of 1 with NH4PF6 in DMF gave rise to the more soluble complex [Au(Tab)2]2(PF6)2 (2). Treatment of 2 with K[Au(CN)2] produced a tetranuclear gold(I) complex {[(Tab)2Au][Au(CN)2]}2 (3). Analogous reactions of two known mononuclear complexes [Ag(Tab)2](PF6) (4) and [Hg(Tab)2](PF6)2 (5) with 1 or 2 equiv of K[Au(CN)2] generated one Ag2Au2 complex {[(Tab)2Ag][Au(CN)2]}2 (6) and one Au/Hg complex {[Hg(Tab)2][Au(CN)2]2} (7), respectively. Compounds 1-3, 6, and 7 were fully characterized by elemental analysis, IR spectra, UV-vis spectra, 1H NMR, and single-crystal X-ray crystallography. 1 and 2 have a similar [Au(Tab)2]2(2+) dimeric structure in which the two [Au(Tab)2]+ cations are connected via one Au-Au aurophilic interaction. In the structure of 3 or 6, each of the two pairs of [M(Tab)2]+ cation and [Au(CN)2]- anion is held together via ionic interactions to form a {[(Tab)2M][Au(CN)2]} species (M = Au, 3; Ag, 6). Two such species are further connected by one Au-Au aurophilic bonding interaction to form an uncommon Au(4) or Ag2Au2 linear string structure with three ligand-unsupported metal-metal bonds. For 7, the [Hg(Tab)2]2+ dication and the [Au(CN)2]2(2-) dianion are interconnected by the secondary Hg...N(CN) interactions to form a 1D chain structure. The thermal and luminescent properties of 1-3, 6, and 7 in solid state were also investigated.     

Luminescent homo- and heteropolynuclear platinum(II) chalcogenido aggregates based on [Pt2E2(P empty set N)4] units (E=S,Se)

A series of homodinuclear platinum(II) complexes containing bridging chalcogenido ligands, [Pt(2)(mu-E)(2)(P empty set N)(4)] (P empty set N=dppy, E=S (1), Se (2); P empty set N=tBu-dppy, E=S (3)) (dppy=2-(diphenylphosphino)pyridine, tBu-dppy=4-tert-butyl-2-(diphenylphosphino)pyridine) have been synthesized and characterized. The nucleophilicity of the [Pt(2)E(2)] unit towards a number of d(10) metal ions and complexes has been demonstrated through the successful isolation of a number of novel heteropolynuclear platinum(II)-copper(I), -silver(I), and -gold(I) complexes: [[Pt(2)(mu(3)-E)(2)(dppy)(4)](2)Ag(3)](PF(6))(3) (E=S (4); Se (5)) and [Pt(2)(dppy)(4)(mu(3)-E)(2)M(2)(dppm)]X(2) (E=S, M=Ag, X=BF(4) (6); E=S, M=Cu, X=PF(6) (7); E=S, M=Au, X=PF(6) (8); E=Se, M=Ag, X=PF(6) (9); E=Se, M=Au, X=PF(6) (10)). Some of them display short metal.metal contacts. These complexes have been found to possess interesting luminescence properties. Through systematic comparison studies, the emission origin has been probed.     

Luminescent heteronuclear Au(I)5Ag(I)8 complexes of [1,2,3-C6(C6H4R-4)3]3- (R = H, CH3, But) by cyclotrimerization of arylacetylides

Unusual AuI-AgI heterometallic complexes [Au5Ag8(mu-dppm)4{1,2,3-C6(C6H4R-4)3}(CCC6H4R-4)7]3+ (R = H 1, CH3 2, But 3) were isolated by reactions of polymeric silver arylacetylides (AgCCC6H4R-4)n with binuclear gold component [Au2(mu-dppm)2(MeCN)2]2+ (dppm = bis(diphenylphosphino)methane), in which cyclotrimerization of arylacetylide -CCC6H4R-4 affords trianion {1,2,3-C6(C6H4R-4)3}3- with an unprecedented mu5-bonding mode. Compounds 1(SbF6)3-3(SbF6)3 exhibit intense photoluminescence derived from an MLCT (Au5Ag8 --> CCC6H4R-4) transition, mixed with a metal cluster-centered excited states.     

Photoluminescence properties of four-coordinate gold(I)-phosphine complexes of the types [Au(diphos)2]PF6 and [Au2(tetraphos)2](PF6)2

Numerous reports describe the photoluminescence of two- and three-coordinate gold(I)-phosphine complexes, but emission in their analogous four-coordinate complexes is almost unknown. This work examines the luminescence of tetrahedral gold(I) complexes of the types [Au(diphos)(2)]PF(6) (diphos = 1,2-bis(diphenylphosphino)ethane, 1) and [Au(2)(tetraphos)(2)](PF(6))(2) (tetraphos = (R,R)-(+/-)/(R,S)-1,1,4,7,10,10-hexaphenyl-1,4,7,10-tetraphosphadecane, (R,R)-(+/-)/(R,S)-2). Although nonemitting in solution, these complexes luminesce with an intense yellow color (lambda(max) 580-620 nm) at 293 K in the solid state or when immobilized as molecular dispersions within solid matrixes. The excited-state lifetimes of the emissions (tau 4.1-9.4 micros) are markedly dependent on the inter- and intramolecular phenyl-phenyl pairing interactions present. At 77 K in an ethanol glass, two transitions are observed: a minor emission at lambda(max) 415-450 nm and a major emission at lambda(max) 520-595 nm. For [Au(1)(2)]PF(6), lifetimes of tau 251.0 +/- 20.5 micros were determined for the former transition and tau 14.9 +/- 4.6 micros for the latter. Density functional theory (DFT) calculations and comparative studies indicate that the former of these emissions involves triplet LMCT pi(Ph) --> Au(d)-P(p) transitions associated with individual P-phenyl groups. The latter emissions, which are the only ones observed at 293 K, are assigned to LMCT pi(Ph-Ph) --> Au(d)-P(p) transitions associated with excited P-phenyl dimers. Other tetrahedral gold(I)-phosphine complexes containing paired P-Ph substituents display similar emissions. The corresponding phosphine ligands, whether free, protonated, or bound to Ag(I), do not exhibit comparable emissions. Far from being rare, luminescence in four-coordinate Au(I)-phosphine complexes appears to be general when stacked P-phenyl groups are present.     

Chemistry and electrochemistry of the heterodinuclear complex ClPd(dppm)2PtCl: a M-M' bond providing site selectivity

The heterodinuclear d(9)-d(9) title compound 1, whose crystal structure has been solved, reacts with dppm [bis(diphenylphosphino)methane] in the presence of NaBF4 to generate the salt [ClPd(mu-dppm)2Pt(eta(1)-dppm)][BF4] (2a), which contains a Pt-bound dangling dppm ligand. 2a has been characterized by 1H and 31P NMR, Fourier transform Raman [nu(Pd-Pt) = 138 cm(-1)], and UV-vis spectroscopy [lambda(max)(dsigma-dsigma*) = 366 nm]. In a similar manner, [ClPd(mu-dppm)2Pt(eta(1)-dppm=O)][BF4] (2b), ligated with a dangling phosphine oxide, has been prepared by the addition of dppm=O. The molecular structure of 2b has been established by an X-ray diffraction study. 2a reacts with 1 equiv of NaBH4 to form the platinum hydride complex [(eta(1)-dppm)Pd(mu-dppm)2Pt(H)][BF4] (3). Both 2a and 3 react with an excess of NaBH4 to provide the mixed-metal d(10)-d(10) compound [Pd(mu-dppm)3Pt] (4). The photophysical properties of 4 were studied by UV-vis spectroscopy [lambda(max)(dsigma-dsigma*) = 460 nm] and luminescence spectroscopy (lambda(emi) = 724 nm; tau(e) = 12 +/- 1 micros, 77 K). The protonation of 1 and 4 leads to [ClPd(mu-dppm)2(mu-H)PtCl]+ (5) and 3, respectively. Stoichiometric treatment of 1 with cyclohexyl or xylyl isocyanide yields [ClPd(mu-dppm)2Pt(CNC6H11)]Cl (6a) and [ClPd(mu-dppm)2Pt(CN-xylyl)]Cl (6b) ligated by terminal-bound CNR ligands. In contrast, treatment of 1 with the phosphonium salt [C[triple bond]NCH2PPh3]Cl affords the structurally characterized A-frame compound [ClPd(mu-dppm)2(mu-C=NCH2PPh3)PtCl]Cl (6c), spanned by a bridging isocyanide ligand. The electrochemical reduction of 2a at -1.2 V vs SCE, as well as the reduction of 5 in the presence of dppm, leads to a mixture of products 3 and 4. Further reduction of 3 at -1.7 V vs SCE generates 4 quantitatively. The reoxidation at 0 V of 4 in the presence of Cl- ions produces back complex 2a. The whole mechanism of the reduction of 1 has been established.     

Synthesis, characterization, and X-ray structure determination of [Au18(P)2(PPh)4(PHPh)(dppm)6]Cl3

The reaction of [(AuCl)2dppm] (dppm=Ph2PCH2PPh2) with PhP(SiMe3)2 and P(SiMe3)3 leads to the formation of the gold cluster compound [Au18(P)2(PPh)4(PHPh)(dppm)6]Cl3 (1). The crystal structure investigation shows a central Au7P2 unit formed by two P centered gold tetrahedra sharing the central gold corner. This central unit is surrounded by a 10-membered Au5P5 ring which, together with the remaining six gold atoms, builds two Au4P rectangular and two Au3P trigonal pyramids. The different structure motifs are connected by the phosphine ligands. The compound has been characterized using microanalysis, IR spectroscopy, ESI-MS, and 31P NMR techniques. Luminescence measurements have also been carried out.     

Heterobimetallic coordination polymers incorporating [M(CN)(2)](-) (M = Cu,Ag) and [Ag(2)(CN)(3)](-) units: increasing structural dimensionality via M-M' and M...NC interactions

A series of new heterometallic coordination polymers has been prepared from the reaction of metal-ligand cations and KAg(CN)(2) units. Many of these contain silver-silver (argentophilic) interactions, analogous to gold-gold interactions, which serve to increase supramolecular structural dimensionality. Compared to [Au(CN)(2)](-) analogues, these polymers display new trends specific to [Ag(CN)(2)](-), including the formation of [Ag(2)(CN)(3)](-) and the presence of Ag...N interactions. [Cu(en)(2)][Ag(2)(CN)(3)][Ag(CN)(2)] (1, en = ethylenediamine) forms 1-D chains of alternating [Ag(CN)(2)](-) and [Ag(2)(CN)(3)](-) units via argentophilic interactions of 3.102(1) A. These chains are connected into a 2-D array by strong cyano(N)-Ag interactions of 2.572(3) A. [Cu(dien)Ag(CN)(2)](2)[Ag(2)(CN)(3)][Ag(CN)(2)] (2, dien = diethylenetriamine) forms a 1-D chain of alternating [Cu(dien)](2+) and [Ag(CN)(2)](-) ions with the Cu(II) atoms connected in an apical/equatorial fashion. These chains are cross-linked by [Ag(2)(CN)(3)](-) units via argentophilic interactions of 3.1718(8) A and held weakly in a 3-D array by argentophilic interactions of 3.2889(5) A between the [Ag(CN)(2)](-) in the 2-D array and the remaining free [Ag(CN)(2)](-). [Ni(en)][Ni(CN)(4)].2.5H(2)O (4) was identified as a byproduct in the reaction to prepare the previously reported [Ni(en)(2)Ag(2)(CN)(3)][Ag(CN)(2)] (3). In [Ni(tren)Ag(CN)(2)][Ag(CN)(2)] (5, tren = tris(2-aminoethyl)amine), [Ni(tren)](2+) cations are linked in a cis fashion by [Ag(CN)(2)](-) anions to form a 1-D chain similar to the [Au(CN)(2)](-) analogue. [Cu(en)Cu(CN)(2)Ag(CN)(2)] (6) is a trimetallic polymer consisting of interpenetrating (6,3) nets stabilized by d(10)-d(10) interactions between Cu(I)-Ag(I) (3.1000(4) A). Weak antiferromagnetic coupling has been observed in 2, and a slightly stronger exchange has been observed in 6. The Ni(II) complexes, 4 and 5, display weak antiferromagnetic interactions as indicated by their relatively larger D values compared to that of 3. Magnetic measurements on isostructural [Ni(tren)M(CN)(2)][M(CN)(2)] (M = Ag, Au) show that Ag(I) is a more efficient mediator of magnetic exchange as compared to Au(I). The formation of [Ni(CN)(4)](2)(-), [Ag(2)(CN)(3)](-), and [Cu(CN)(2)](-) are all attributed to secondary reactions of the dissociation products of the labile KAg(CN)(2).     

Synthesis and luminescence behaviour of novel heterodecanuclear silver(I)-rhenium(I) alkynyl complexes. X-ray crystal structures of [Ag6(mu-dppm)4[mu3-C[triple bond]CC[triple bond]C-Re(Me2bpy)(CO)3]4](PF6)2 and [Ag6(mu-dppm)4[mu3-C[triple bond]CC[triple bond]C-Re(Br2phen)(CO)3]4](PF6)2

A novel series of luminescent heterodecanuclear mixed-metal alkynyl complexes, [Ag6(mu-dppm)4[mu3-C[triple bond]CC[triple bond]C-Re(N--N)(CO)3]4](PF6)2, (N--N = tBu2bpy, Me2bpy, phen, Br2phen), have been successfully synthesized; the X-ray crystal structures of [Ag6(mu-dppm)4[mu3-C[triple bond]CC[triple bond]C-Re(Me2bpy)(CO)3]4](PF6)2 and [Ag6(mu-dppm)4[mu3-C[triple bond]CC[triple bond]C-Re(Br2phen)(CO)3]4](PF6)2 have also been determined.     

Self-assembly luminescent heteroheptanuclear complexes with metal diphosphine and metal thiolate as components

Self-assembly between the building blocks [M2(mu-dppm)2(MeCN)2]2+ (M = Cu or Ag; dppm = bis(diphenylphosphino)methane) and M'(aet)2 (aet = 2-aminoethanethiolate) afforded luminescent heterohepta-nuclear complexes [Cu4M'3(mu-dppm)3(mu 3-aet)4(mu-aet)2]4+ (M' = Ni 1; Pd 2) or heterotrinuclear complexes [Ag2M'(mu-dppm)2(mu-aet)2]2+ (M' = Ni 3, Pd 4).     

Structural, dynamic, and theoretical studies of [AunPt2(PPh3)4(mu-S)2-n(mu 3-S)nL][PF6]n [n = 1, L = PPh3; n = 2, L = Ph2PCH2PPh2, (C5H4PPh2)2Fe

Three heterometallic Au-Pt complexes [Pt2(PPh3)4(mu-S)(mu 3-S)Au(PPh3)][PF6] (2), [Pt2(PPh3)4(mu 3-S)2Au2(mu-dppm)]-[PF6]2 (3), and [Pt2(PPh3)4(mu 3-S)2Au2(mu-dppf)][PF6]2 (4) have been synthesized from Pt2(PPh3)4(mu-S)2 (1) [dppm = Ph2PCH2PPh2; dppf = (C5H4PPh2)2Fe] and characterized by single-crystal X-ray crystallography. In 2, the Au(I) atom is anchored on only one of the sulfur centers. In 3 and 4, both sulfur atoms are aurated, showing the ability of 1 to support an overhead bridge structure, viz. [Au2(P-P)], with or without the presence of Au-Au bond. The change of dppf to dppm facilitates such active interactions. Two stereoisomers of complex 3 (3a,b) have been obtained and characterized by single-crystal X-ray crystallography. NLDFT calculations on 2 show that the linear coordination mode is stabilized with respect to the trigonal planar mode by 14.0 kJ/mol. All complexes (2-4) are fluxional in solution with different mechanisms. In 2, the [Au(PPh3)] fragment switches rapidly between the two sulfur sites. Our hybrid MM-NLDFT calculations found a transition state in which the Au(I) bears an irregular trigonal planar geometry (delta G++ = 19.9 kJ/mol), as well as an intermediate in which Au(I) adopts a regular trigonal planar geometry. Complexes 3a,b are roughly diastereoisomeric and related by sigma (mirror plane) conversion. This symmetry operation can be broken down to two mutually dependent fluxional processes: (i) rapid flipping of the dppm methylene group across the molecular plane defined by the overhead bridge; (ii) rocking motion of the two Au atoms across the S...S axis of the (Pt2S2) core. Modeling of the former by molecular mechanics yields a steric barrier of 29.0 kJ/mol, close to that obtained from variable-temperature 31P(1Hz) NMR study (33.7 kJ/mol). In 4, the twisting of the ferrocenyl moiety across the S...S axis is in concert with a rocking motion of the two gold atoms. The movement of dppf is sterically most demanding, and hence, 4 is the only complex that shows a static structure at lower temperatures. Pertinent crystallographic data: (2) space group P1, a = 15.0340(5) A, b = 15.5009(5) A, c = 21.9604(7) A, alpha = 74.805(1) degrees, beta = 85.733(1) degrees, gamma = 78.553(1) degrees, R = 0.0500; (3a) space group Pna2(1), a = 32.0538(4) A, b = 16.0822(3) A, c = 18.9388(3) A, R = 0.0347; (3b) space group Pna2(1), a = 31.950(2) A, b = 16.0157(8) A, c = 18.8460(9) A, R = 0.0478; (4) space group P2(1)/c, a = 13.8668(2) A, b = 51.7754(4) A, c = 15.9660(2) A, beta = 113.786(1) degrees, R = 0.0649.     

Metallophilic attractions between d8-d10 heterometallic compounds trans-[Pt(PH3)2(CN)2] and M(PH3)2+ (M=Ag or Cu): Ab initio study

The weak metal-metal interactions of Pt(II)-Ag(I)/Cu(I) have been investigated by ab initio method at MP2 level through the model complexes [trans-Pt(PH3)2(CN)2-M(PH3)2+] (M=Ag,Cu). The calculated interaction energy of 12.9 and 11.5 kcal mol(-1) for [trans-Pt(PH3)2(CN)2-Ag(PH3)2+] and [trans-Pt(PH3)2(CN)2-Cu(PH3)2+] respectively, are in the middle of the van der Waals force and the strong hydrogen bond. The estimated equilibrium separations between Pt and M, r(eq)(Pt-M) (3.32 A for M=Ag and 3.23 A for M=Cu), lie within the region expected for weak metal-metal interaction. The electronic dispersive contributions dominate the weak interaction.     

Metallophilicity versus pi-pi interactions: ligand-unsupported argentophilicity/cuprophilicity in oligomers-of-dimers [M2L2]n (M=CuI or AgI, L=tridentate ligand)

To verify whether attractive metallophilic interactions exist in the dimer-of-dimers [Cu(2)(ophen)(2)](2) (Hophen=1H-[1,10]phenanthrolin-2-one) (1), we designed and synthesized a series of such [M(2)L(2)](2) structures by varying the d(10) metal and/or the ligand (M=Cu(I) or Ag(I), L=ophen or obpy; Hobpy=1H-[2,2']bipyridinyl-6-one), and have successfully obtained three dimers-of-dimers: [Ag(2)(ophen)(2)](2).6 H(2)O (2), [Cu(2)(obpy)(2)](2) (3), and [Ag(2)(obpy)(2)](2).4.5 H(2)O.0.5 DMF (4). X-ray analyses of these structures show that interdimer M-M separations in [Ag(2)-(ophen)(2)](2) (3.199 A) are remarkably shorter than those in [Cu(2)(ophen)(2)](2) (3.595 A). Shorter interdimer M-M separations are found in the structures of [M(2)(obpy)(2)](2) (2.986 and 2.993 A in [Cu(2)(obpy)(2)](2), 3.037 to 3.093 A in [Ag(2)(obpy)(2)](2)), in which the pi systems are smaller than in the complexes with the ophen ligand. Detailed structural comparison of these dimers-of-dimers indicates that the interdimer, face-to-face pi-pi interactions repulse rather than support the interdimer metal-metal attractive interactions. This study also yields qualitative comparison of the strengths between argentophilic, cuprophilic, and face-to-face pi-pi interactions. DFT calculations on the four dimers-of-dimers further support the above deduction. The structure of a trimer-of-dimers [Ag(2)(obpy)(2)](3) (Ag-Ag 3.171 to 3.274 A) is further evidence that the oligomerization of the [M(2)L(2)] molecules is favored by stronger metallophilic and weaker face-to-face pi-pi interactions.     

Luminescent di- and polynuclear organometallic gold(I)-metal (Au2, {Au2Ag}n and {Au2Cu}n) compounds containing bidentate phosphanes as active antimicrobial agents

The reaction of new dinuclear gold(I) organometallic complexes containing mesityl ligands and bridging bidentate phosphanes [Au(2)(mes)(2)(μ-LL)] (LL=dppe: 1,2-bis(diphenylphosphano)ethane 1a, and water-soluble dppy: 1,2-bis(di-3-pyridylphosphano)ethane 1b) with Ag(+) and Cu(+) lead to the formation of a family of heterometallic clusters with mesityl bridging ligands of the general formula [Au(2)M(μ-mes)(2) (μ-LL)][A] (M=Ag, A=ClO(4)(-), LL=dppe 2a, dppy 2b; M=Ag, A=SO(3)CF(3)(-), LL=dppe 3a, dppy 3b; M=Cu, A=PF(6)(-), LL=dppe 4a, dppy 4b). The new compounds were characterized by different spectroscopic techniques and mass spectrometry The crystal structures of [Au(2)(mes)(2)(μ-dppy)] (1b) and [Au(2)Ag(μ-mes)(2)(μ-dppe)][SO(3)CF(3)] (3a) were determined by a single-crystal X-ray diffraction study. 3a in solid state is not a cyclic trinuclear Au(2)Ag derivative but it gives an open polymeric structure instead, with the {Au(2)(μ-dppe)} fragments "linked" by {Ag(μ-mes)(2)} units. The very short distances of 2.7559(6)?? (Au-Ag) and 2.9229(8)?? (Au-Au) are indicative of gold-silver (metallophilic) and aurophilic interactions. A systematic study of their luminescence properties revealed that all compounds are brightly luminescent in solid state, at room temperature (RT) and at 77?K, or in frozen DMSO solutions with lifetimes in the microsecond range and probably due to the self-aggregation of [Au(2)M(μ-mes)(2)(μ-LL)](+) units (M=Ag or Cu; LL=dppe or dppy) into an extended chain structure, through Au-Au and/or Au-M metallophilic interactions, as that observed for 3a. In solid state the heterometallic Au(2)M complexes with dppe (2a-4a) show a shift of emission maxima (from ca. 430 to the range of 520-540?nm) as compared to the parent dinuclear organometallic product 1a while the complexes with dppy (2b-4b) display a more moderate shift (505 for 1b to a max of 563?nm for 4b). More importantly, compound [Au(2)Ag(μ-mes)(2)(μ-dppy)]ClO(4) (2b) resulted luminescent in diluted DMSO solution at room temperature. Previously reported compound [Au(2)Cl(2)(μ-LL)] (LL dppy 5b) was also studied for comparative purposes. The antimicrobial activity of 1-5 and Ag[A] (A=ClO(4)(-), SO(3)CF(3)(-)) against gram-positive and gram-negative bacteria and yeast was evaluated. Most tested compounds displayed moderate to high antibacterial activity while heteronuclear Au(2)M derivatives with dppe (2a-4a) were the more active (minimum inhibitory concentration 10 to 1?μg?mL(-1)). Compounds containing silver were ten times more active to gram-negative bacteria than the parent dinuclear compound 1a or silver salts. Au(2)Ag compounds with dppy (2b, 3b) were also potent against fungi.     

Synthesis and reactivity of the ruthenium(II) dithiocarbonate complex [Ru(kappa2-S2C=O)(dppm)2] (dppm = bis(diphenylphosphino)methane)

Reaction of cis-[RuCl2(dppm)2] (dppm = bis(diphenylphosphino)methane) with CS2 and NaOH yields the first ruthenium dithiocarbonate complex, [Ru(kappa2-S2C=O)(dppm)2]. Protonation with tetrafluoroboric acid affords the xanthate complex [Ru(kappa2-S2COH)(dppm)2]BF4 in a reversible manner, suggesting that this may be an intermediate in dithiocarbonate formation. [Ru(kappa2-S2C=O)(dppm)2] reacts with methyl iodide or [Me3O]BF4 to give [Ru(kappa2-S2COMe)(dppm)2]+, also obtained from the reaction of cis-[RuCl2dppm)2] with CS2 and NaOMe. Two modifications of [Ru(kappa2-S(2)C=O)(dppm)2] were examined crystallographically and the structure of [Ru(kappa2-S2COMe)(dppm)2]BF4 and a new modification of cis-[RuCl2(dppm)2] are also reported.     

Group 11 complexes containing the [C5(CN)5]- ligand; 'coordination-analogues' of molecular organometallic systems

The reactions of Na[C(5)(CN)(5)] (Na[1]) with group 11 phosphine complexes [(P)(n)MCl] (M = Cu, Ag, Au, P = Ph(3)P; M = Cu, P = dppe (Ph(2)PCH(2)CH(2)PPh(2))] give a range of compounds containing the pentacyanocyclopentadienide ligand, [C(5)(CN)(5)](-) (1). The new complexes [(Ph(3)P)(2)M{1}](2) [M = Cu (3); M = Ag (5)], [(Ph(3)P)(3)Ag{1}] (4), [(dppe)(3)Cu(2){1}(2)] (6) and [Au(PPh(3))(2)][1] (7) include the first complete series of group 11 complexes of any cyclopentadienide ligand to be structurally characterised.     

Electronic and Geometric Structure of Bimetallic Clusters: Density Functional Calculations on [M(4){Fe(CO)(4)}(4)](4-) (M = Cu, Ag, Au) and [Ag(13){Fe(CO)(4)}(8)](n)(-) (n = 0-5)

The results of all-electron density functional calculations on the bimetallic cluster compounds [M(4){Fe(CO)(4)}(4)](4-) (M = Cu, Ag, Au) and on the corresponding naked species M(4)Fe(4) are reported. The trends within the triad have been investigated. The bare metal clusters exhibit a strong magnetization which is quenched on addition of CO ligands. The bonding in the bare clusters is different for the silver derivative compared to that of copper and gold, resulting in comparatively weaker Ag-Fe and Ag-Ag bonds. This can be rationalized in terms of the different d-sp mixing, which for Cu and Au is larger than for Ag. Relativistic effects act to increase the 4d-5s mixing in Ag and to strengthen the intermetallic bond with Fe. In the carbonylated clusters a charge transfer from the metal M (M = Cu, Ag, or Au) to the Fe(CO)(4) groups occurs so that the atoms M can be considered in a formal +I oxidation state, rationalizing the nearly square-planar geometry of the metal frame. In fact, the local coordination of the M atoms is almost linear, as expected for complexes of M(I). The addition of extra electrons results in a stabilization of the clusters, indicating the electron-deficient nature of these compounds. Similar features have been found for the largest cluster synthesized so far for this class of compounds, [Ag(13){Fe(CO)(4)}(8)](n)(-), (n = 0-5). The nature and localization of the unpaired electron in the tetraanion is also discussed.     

First-principles investigation of transition metal atom M (M = Cu, Ag, Au) adsorption on CeO2(110)

Transition metal atom M (M = Cu, Ag, Au) adsorption on CeO(2)(110), a technologically important catalytic support surface, is investigated with density-functional theory within the DFT+U formalism. A set of model configurations was generated by placing M at three surface sites, viz., on top of an O, an O bridge site, and a Ce bridge site. Prior to DFT optimization, small distortions in selected Ce-O distances were imposed to explore the energetics associated with reduction of Ce(4+) to Ce(3+) due to charge transfer to Ce during M adsorption. Charge redistribution is confirmed with spin density isosurfaces and site projected density of states. We demonstrate that Cu and Au atoms can be oxidized to Cu(2+) and Au(2+), although the adsorption energy, E(ads), of Au(2+) is less favorable and, unlike Cu(2+), it has not been experimentally observed. Oxidation of Ag always results in Ag(+). For M adsorption at an O bridge site, E(ads)(2NN) > E(ads)(3NN) > E(ads)(1NN) where NN denotes the nearest neighbor Ce(3+) site relative to M. Alternatively, for M adsorption at a Ce bridge site, E(ads)(3NN) > E(ads)(2NN) > E(ads)(1NN). The adsorption behavior of M on CeO(2) (110) is compared with M adsorption on CeO(2)(111).