Diaminogermylene and diaminostannylene derivatives of gold(I): novel AuM and AuM2 (M = Ge, Sn) complexes

The reactions of [AuCl(THT)] (THT = tetrahydrothiophene) with 1 equiv of the group 14 diaminometalenes M(HMDS)(2) [M = Ge, Sn; HMDS = N(SiMe(3))(2)] lead to [Au{MCl(HMDS)(2)}(THT)] [M = Ge (1), Sn (2)], which contain a metalate(II) ligand that arises from insertion of the corresponding M(HMDS)(2) reagent into the Au-Cl bond of the gold(I) reagent. While compound 1 reacts with more Ge(HMDS)(2) to give the germanate-germylene derivative [Au{GeCl(HMDS)(2)}{Ge(HMDS)(2)}] (3), which results from substitution of Ge(HMDS)(2) for the THT ligand of 1, an analogous treatment of compound 2 with Sn(HMDS)(2) gives the stannate-stannylene derivative [Au{SnCl(HMDS)(2)}{Sn(HMDS)(2)(THT)}] (4), which has a THT ligand attached to the stannylene tin atom and which, in solution at room temperature, participates in a dynamic process that makes its two Sn(HMDS)(2) fragments equivalent (on the NMR time scale). A similar dynamic process has not been observed for the AuGe(2) compound 3 or for the AuSn(2) derivatives [Au{SnR(HMDS)(2)}{Sn(HMDS)(2)(THT)}] [R = Bu (5), HMDS (6)], which have been prepared by treating complex 4 with LiR. The structures of compounds 1 and 3-6 have been determined by X-ray diffraction.     

Synthesis and X-ray structures of dinuclear and trinuclear gold(I) and dinuclear gold(II) amidinate complexes

The structures of the trinuclear gold(I), [Au(3)(2,6-Me(2)-form)(2)-(THT)Cl], the dinuclear [Au(2)(2,6-Me(2)-form)(2)], and the oxidative-addition product [Au(2)(2,6-Me(2)-form)(2)Cl(2)] formamidinate complexes are reported. The trinuclear complex is stable with gold-gold distances 3.01 and 3.55 A. The gold-gold distance in the dinuclear complex decreases upon oxidative-addition with halogens from 2.7 to 2.5 A, similar to observations made with the dithiolates and ylides.     

Selenolate gold complexes with aurophilic Au(I)-Au(I) and Au(I)-Au(III) interactions

The gold(I) selenolate compound [Au(2)(SePh)(2)(mu-dppf)] (dppf = 1,1'-bis(diphenylphosphino)ferrocene) has been prepared by reaction of [Au(2)Cl(2)(mu-dppf)] with PhSeSiMe(3) in a molar ratio 1:2. This complex reacts with gold(I) or gold(III) derivatives to give polynuclear gold(I)-gold(I) or gold(I)-gold(III) complexes of the type [Au(4)(mu-SePh)(2)(PPh(3))(2)(mu-dppf)](OTf)(2), [Au(3)(C(6)F(5))(3)(mu-SePh)(2)(mu-dppf)], or [Au(4)(C(6)F(5))(6)(mu-SePh)(2)(mu-dppf)], with bridging selenolate ligands. The reaction of [Au(2)(SePh)(2)(mu-dppf)] with 1 equiv of AgOTf leads to the formation of the insoluble Ag(SePh) and the compound [Au(2)(mu-SePh)(mu-dppf)]OTf. The complexes [Au(4)(C(6)F(5))(6)(mu-SePh)(2)(mu-dppf)] and [Au(2)(mu-SePh)(mu-dppf)]OTf (two different solvates) have been characterized by X-ray diffraction studies and show the presence of weak gold(I)-gold(III) interactions in the former and intra- and intermolecular gold(I)-gold(I) inter-actions in the later.     

Molecular design of luminescence ion probes for various cations based on weak gold(I)...gold(I) interactions in dinuclear gold(I) complexes

A series of luminescent dinuclear gold(I) complexes with different crown ether pendants, [Au(2)(PwedgeP)(S-B15C5)(2)] [S-B15C5 = 4'-mercaptobenzo-15-crown-5, P(wedge)P = bis(dicyclohexylphosphino)methane (dcpm) (1), bis(diphenylphosphino)methane (dppm) (2)] and [Au(2)(P(wedge)P)(S-B18C6)(2)] [S-B18C6 = 4'-mercaptobenzo-18-crown-6, P(wedge)P = dcpm (3), dppm (4)], and their related crown-free complexes, [Au(2)(P(wedge)P)(SC(6)H(3)(OMe)(2)-3,4)(2)] [P(wedge)P = dcpm (5), dppm (6)], were synthesized. The low-energy emission of the mercaptocrown ether-containing gold(I) complexes are tentatively assigned as originated from states derived from a S --> Au ligand-to-metal charge transfer (LMCT) transition. The crown ether-containing gold(I) complexes showed specific binding abilities toward various metal cations according to the ring size of the crown pendants. Spectroscopic evidence was provided for the metal-ion-induced switching on of the gold...gold interactions upon the binding of particular metal ions in a sandwich binding mode.     

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.     

Heterovalent Au(III)-M(I) (M=Cu, Ag, Au) complexes derived from incorporation of [Au(tdt)2]- (tdt = toluene-3,4-dithiolate) with [M2(dppm)2]2+ (dppm = Bis(diphenylphosphino)methane)

Polynuclear heterovalent Au(III)-M(I) (M = Cu, Ag, Au) cluster complexes [Au(III)Cu(I)8(mu-dppm)3(tdt)5]+ (1), [Au(III)3Ag(I)8(mu-dppm)4(tdt)8]+ (2), and [Au(III)Au(I)4(mu-dppm)4(tdt)2]3+ (3) were prepared by reaction of [Au(III)(tdt)2]- (tdt = toluene-3,4-dithiolate) with 2 equiv of [M(I)2(dppm)2]2+ (dppm = bis(diphenylphosphino)methane). Complex 3 originates from incorporation of one [Au(III)(tdt)2]- with two [Au(I)2(dppm)2]2+ components through Au(III)-S-Au(I) linkages. Formation of complexes 1 and 2, however, involves rupture of metal-ligand bonds in the metal components and recombination between the ligands and the metal atoms. The Au(tdt)2 component connects to four M(I) atoms through Au(III)-S-M(I) linkages in syn and anti conformations in complexes 1 (M = Cu) and 3 (M = Au), respectively, but in both syn and anti conformations in complex 2 (M = Ag). The tdt ligand exhibits five types of bonding modes in complexes 1-3, chelating Au(III) or M(I) atoms as well as bridging Au(III)-M(I) or M(I)-M(I) atoms in different orientations. Although complexes 1 and 2 are nonemissive, Au(III)Au(I)(4) complex 3 shows room-temperature luminescence with emission maximum at 555 nm (tau(em) = 3.1 micros) in the solid state and at 570 nm (tau(em) = 1.5 micros) in acetonitrile solution.     

Gold(I) Complexes with the nido-Diphosphino Ligand [7,8-(Ph(2)P)(2)-7,8-C(2)B(9)H(10)](-). Preparation of the First Metallocarborane Complex of this Ligand. Crystal Structures of [Au{(PPh(2))(2)C(2)B(9)H(10)}(PPh(3))].CH(2)Cl(2) and [Au(2){(PPh(2))(2)C(2)B(9)H(10)}(2){(PPh(2))(2)(CH(2))(3)}].3Me(2)CO

The reaction of [AuCl(PR(3))] with [1,2-(Ph(2)P)(2)-1,2-C(2)B(10)H(10)] in refluxing ethanol proceeds with partial degradation (removal of a boron atom adjacent to carbon) of the closo species to give [Au{(PPh(2))(2)C(2)B(9)H(10)}(PR(3))] [PR(3) = PPh(3) (1), PPh(2)Me (2), PPh(2)(4-Me-C(6)H(4)) (3), P(4-Me-C(6)H(4))(3) (4), P(4-OMe-C(6)H(4))(3) (5)]. Similarly, the treatment of [Au(2)Cl(2)(&mgr;-P-P)] with [1,2-(Ph(2)P)(2)-1,2-C(2)B(10)H(10)] under the same conditions leads to the complexes [Au(2){(PPh(2))(2)C(2)B(9)H(10)}(2)(&mgr;-P-P)] [P-P = dppe = 1,2-bis(diphenylphosphino)ethane (6), dppp = 1,3-bis(diphenylphosphino)propane (7)], where the dppe or dppp ligands bridge two gold nido-diphosphine units. The reaction of 1 with NaH leads to removal of one proton, and further reaction with [Au(PPh(3))(tht)]ClO(4) gives the novel metallocarborane compound [Au(2){(PPh(2))(2)C(2)B(9)H(9)}(PPh(3))(2)] (8). The structure of complexes 1 and 7 have been established by X-ray diffraction. [Au{(PPh(2))(2)C(2)B(9)H(10)}(PPh(3))] (1) (dichloromethane solvate) crystallizes in the monoclinic space group P2(1)/c, with a = 17.326(3) ?, b = 20.688(3) ?, c = 13.442(2) ?, beta = 104.710(12) degrees, Z = 4, and T = -100 degrees C. [Au(2){(PPh(2))(2)C(2)B(9)H(10)}(2)(&mgr;-dppp)] (7) (acetone solvate) is triclinic, space group P&onemacr;, a = 13.432(3) ?, b = 18.888(3) ?, c = 20.021(3) ?, alpha = 78.56(2) degrees, beta = 72.02(2) degrees, gamma = 73.31(2) degrees, Z = 2, and T = -100 degrees C. In both complexes the gold atom exhibits trigonal planar geometry with the 7,8-bis(diphenylphosphino)-7,8-dicarba-nido-undecaborate(1-) acting as a chelating ligand.     

Synthesis of tris- and tetrakis(pyrazol-1-yl)borate gold(III) complexes. Crystal structures of [Au[kappa(2)-N,N'-BH(Pz)(3)]Cl(2)] (pz = pyrazol-1-yl) and [Au[kappa(2)-N,N'-B(Pz)(4)](kappa(2)-C,N-C(6)H(4)CH(2)NMe(2)-2)]ClO(4).CHCl(3)

Na[BH(pz)(3)] and Na[AuCl(4)].2H(2)O react in water (1:1) to give [Au[kappa(2)-N,N'-BH(pz)(3)]Cl(2)] (1) or, in the presence of NaClO(4) (2:1:1), the cationic complex [Au[kappa(2)-N,N'-BH(pz)(3)](2)]ClO(4) (2). The reactions of Na[B(pz)(4)] with the cyclometalated gold complexes [AuRCl(2)] and NaClO(4) (1:1:1) produce [Au[kappa(2)-N,N'-B(pz)(4)](R)]ClO(4) [R = kappa(2)-C,N-C(6)H(4)CH(2)NMe(2)-2 (3)] or [Au[kappa(2)-N,N'-B(pz)(4)](R)Cl] [R = C(6)H(3)(N=NC(6)H(4)Me-4')-2-Me-5 (4)], respectively, although 4 is better obtained in the absence of NaClO(4). The crystal structures of 1 and 3.CHCl(3) are reported. Both complexes display the gold center in square planar environments, two coordination sites being occupied by the chelating poly(pyrazolyl)borate ligands.     

Synthesis of luminescent gold(I) and gold(III) complexes with a triphosphine ligand

We have synthesized and characterized a series of trinuclear gold(I) complexes [(AuX)(3)(mu-triphos)] (triphos = bis(2-diphenylphosphinoethyl)phenylphosphine; X = Cl 1, Br 2, I 3, C(6)F(5) 4) and di- and trinuclear gold(III) complexes [[Au(C(6)F(5))(3)](n)(mu-triphos)] (n = 2 (5), 3 (6)). The crystal structure of 6 [[Au(C(6)F(5))(3)](3)(mu-triphos)] has been determined by X-ray diffraction studies, which show the triphosphine in a conformation resulting in very long gold-gold distances, probably associated with the steric requirements of the tris(pentafluorophenyl)gold(III) units. Complex 6 crystallizes in the triclinic space group P(-1) with a = 12.7746(16) A, b = 18.560(2) A, c = 21.750(3) A, alpha = 98.215(3) degrees, beta = 101.666(3) degrees, gamma = 96.640(3) degrees, and Z = 2. Chloride substitutions in complex 1 afford trinuclear gold(I) complexes [(AuX)(3)(mu-triphos)] (X = Fmes (1,3,5-tris(trifluoromethyl)phenyl) 7, p-SC(6)H(4)Me 8, SCN 9) and [Au(3)Cl(3)(-)(n)()(S(2)CNR(2))(n)(mu-triphos)] (R = Me, n = 3 (10), 2 (12), 1 (14); R = CH(2)Ph, n = 3 (11), 2 (13), 1 (15)). The luminescence properties of these complexes in the solid state have been studied; at low temperature most of them are luminescent, including the gold(III) derivative 6, with the intensity and the emission maxima being clearly influenced by the nature and the number of the ligands bonded to the gold centers.     

Dinuclear gold(I) dithiophosphonate complexes: synthesis,luminescent properties,and X-ray crystal structures of [AuS(2)PR(OR')](2) (R = Ph,R' = C(5)H(9); R = 4-C(6)H(4)OMe,R' = (1S,5R,2S)-(--)-menthyl; R = Fc,R' = (CH(2))(2)O(CH(2))(2)OMe)

2,4-Diaryl- and 2,4-diferrocenyl-1,3-dithiadiphosphetane disulfide dimers (RP(S)S)(2) (R = Ph (1a), 4-C(6)H(4)OMe (1b), FeC(10)H(9) (Fc) (1c)) react with a variety of alcohols, silanols, and trialkylsilyl alcohols to form new dithiophosphonic acids in a facile manner. Their corresponding salts react with chlorogold(I) complexes in THF to produce dinuclear gold(I) dithiophosphonate complexes of the type [AuS(2)PR(OR')](2) in satisfactory yield. The asymmetrical nature of the ligands allows for the gold complexes to form two isomers (cis and trans) as verified by solution (1)H and (31)P[(1)H] NMR studies. The X-ray crystal structures of [AuS(2)PR(OR')](2) (R = Ph, R' = C(5)H(9) (2); R = 4-C(6)H(4)OMe, R' = (1S,5R,2S)-(-)-menthyl (3); R = Fc, R' = (CH(2))(2)O(CH(2))(2)OMe (4)) have been determined. In all cases only the trans isomer is obtained, consistent with solid state (31)P NMR data obtained for the bulk powder of 3. Crystallographic data for 2 (213 K): orthorhombic, Ibam, a = 12.434(5) A, b = 19.029(9) A, c = 11.760(4) A, V = 2782(2) A(3), Z = 4. Data for 3 (293 K): monoclinic, P2(1), a = 7.288(2) A, b = 12.676(3) A, c = 21.826(4) A, beta = 92.04(3) degrees, V = 2015.0(7) A(3), Z = 2. Data for 4 (213 K): monoclinic, P2(1)/n, a = 11.8564(7) A, b = 22.483(1) A, c = 27.840(2) A, beta = 91.121(1) degrees, V = 7419.8(8) A(3), Z = 8. Moreover, 1a-c react with [Au(2)(dppm)Cl(2)] to form new heterobridged trithiophosphonate complexes of the type [Au(2)(dppm)(S(2)P(S)R)] (R = Fc (12)). The luminescence properties of several structurally characterized complexes have been investigated. Each of the title compounds luminesces at 77 K. The results indicate that the nature of Au...Au interactions in the solid state has a profound influence on the optical properties of these complexes.     

Gold(I) and silver(I) mixed-metal trinuclear complexes: dimeric products from the reaction of gold(I) carbeniates or benzylimidazolates with silver(I) 3,5-diphenylpyrazolate

Trinuclear mixed-metal gold-silver compounds are obtained by the reaction of gold(I) carbeniate [Au(mu-C(OEt)=NC6H4-p-CH3)]3, TR(carb), or gold(I) imidazolate [Au-mu-C,N-1-benzyl-2-imidazolate]3, TR(bzim), with silver(I) pyrazolate [Ag(mu-3,5-Ph2pz)]3. The crystalline products are mixed-ligand, mixed-metal dimeric products [Au(carb)Ag2(mu-3,5-Ph2pz)2], [Au2(carb)2Ag(mu-3,5-Ph2pz)].CH2Cl2, [Au(bzim)2Ag2(mu-3,5-Ph2pz)], and [Au2(bzim)2Ag(mu-3,5-Ph2pz)]. They have been characterized by elemental analysis and 1H NMR and mass spectrometry. The X-ray structure of [Au(carb)Ag2(mu-3,5-Ph2pz)2] shows it to be a dimer with two Ag...Au contacts between the trinuclear units of 3.083(2) and 3.310(2) A and with average intramolecular Ag...Ag and Au...Ag distances of approximately 3.3 and 3.2 A, respectively. The structure of [Au2(carb)2Ag(mu-3,5-Ph2pz)].CH2Cl2 is a dimer with one intermolecular Au...Au attraction of 3.3354(10) A and a short Ag...Au distance of approximately 3.42 A and intramolecular Ag...Au and Au...Au contacts of approximately 3.2 and approximately 3.3 A, respectively. Packing diagrams of both complexes show that the dimeric units are independent, similar to their parent molecules. The dimers of trinuclear [Au(carb)Ag2(mu-3,5-Ph2pz)2] and [Au2(carb)2Ag(mu-3,5-Ph2pz)].CH2Cl2 crystallize in the triclinic space group P (Z = 2), a = 9.688(3) A, b = 15.542(4) A, c = 23.689(6) A, alpha = 82.560(5) degrees , beta = 87.887(6) degrees , gamma = 78.060(5) degrees , and the orthorhombic space group Pca2(1) (Z = 4), a = 29.644(4) A, b = 7.4582(10) A, c = 30.473(4) A, respectively. The structure of [Au(bzim)Ag2(mu-3,5-Ph2pz)2] is a dimer with two metallophilic Ag...Au interactions of 3.14 A. The complex crystallizes in the monoclinic space group C2/c (Z = 4), a = 26.368(5) A, b = 15.672(3) A, c = 17.010(3) A, beta = 102.206(3) degrees .     

Synthesis, structure, and reactions of binuclear gold(I) complexes containing two different bridging ligands

The binuclear cycloaurated compounds [Au(2)(mu-C(6)H(3)-2-PPh(2)-n-Me)(2)] (n = 5, 1a; n = 6, 1b) react with the digold(I) complexes [Au(2)(mu-S(2)CN(n)()Bu(2))(2)] and [Au(2)(mu-dppm)(2)](PF(6))(2) to give heterobridged dinuclear complexes [Au(2)(mu-C(6)H(3)-2-PPh(2)-n-Me)(mu-S(2)CN(n)Bu(2))] (n = 5, 5a; n = 6, 5b) and [Au(2)(mu-C(6)H(3)-2-PPh(2)-n-Me)(mu-dppm)]PF(6), (n = 5, 9a; n = 6, 9b), respectively. Complex 5a exists in the solid state as an infinite zigzag chain of dimeric units with intramolecular Au-Au separations of 2.8331(3) and 2.8243(3) A for independent molecules and intermolecular Au-Au separations of 3.0653(3) and 3.1304(3) A. Both 5a and 5b undergo oxidative addition with halogens to give the heterovalent, gold(I)-gold(III) compounds [XAu(I)(mu-2-Ph(2)PC(6)H(3)-n-Me)Au(III)X(eta(2)-S(2)CN(n)Bu(2))] [n = 5, X = Cl (6a), I (8a); n = 6, X = Cl (6b), Br (7b), I (8b)]. Compound 8a has been shown by X-ray crystallography to contain a gold(III) atom coordinated in a planar array by bidentate, chelating di-n-butyldithiocarbamate, iodide, and the sigma-aryl carbon atom, together with a gold(I) atom that is linearly coordinated by the phosphorus atom of the arylphosphine and by iodide. The intramolecular gold-gold distance of 3.2201(3) A indicates little or no interaction between the metal atoms. In contrast to the behavior of the homobridged complexes 1a and 1b, the heterobridged dithiocarbamate complexes 5a and 5b give structurally similar products on reaction with halogens, irrespective of the position of the ring methyl substituent. Crystal data for [Au(2)(mu-C(6)H(3)-2-PPh(2)-5-Me)(mu-S(2)CN(n)Bu(2))] (5a): triclinic, space group P1 (No. 2), with a = 11.3398(1), b = 15.9750(2), c = 16.4400(3) A, alpha = 91.0735(9), beta = 109.3130(7), gamma = 90.7666(8) degrees, V = 2809.47(6) A(3), and Z = 4. Crystal data for [IAu(I)(mu-2-Ph(2)PC(6)H(3)-5-Me)Au(III)I(eta(2)- S(2)CN(n)Bu(2))] (8a): triclinic, space group P1 (No. 2), with a = 8.6136(2), b = 9.3273, c = 21.1518(4) A, alpha = 84.008(1), beta = 84.945(1), gamma = 75.181(1) degrees, V = 1630.54(6) A(3), and Z = 2.     

Electronic excited states of [Au(2)(dmpm)(3)](ClO(4))(2) (dmpm= bis(dimethylphosphine)methane)

We present studies of the resonance Raman and electronic luminescence spectra of the [Au(2)(dmpm)(3)](ClO(4))(2) (dmpm = bis(dimethylphosphine)methane) complex, including excitation into an intense band at 256 nm and into a weaker absorption system centered about approximately 300 nm. The resonance Raman spectra confirm the assignment of the 256 nm absorption band to a (1)(dsigma --> psigma) transition, a metal-metal-localized transition, in that nu(Au-Au) and overtones of it are strongly enhanced. A resonance Raman intensity analysis of the spectra associated with the 256 nm absorption band gives the ground-state and excited-state nu(Au-Au) stretching frequencies to be 79 and 165 cm(-1), respectively, and the excited-state Au-Au distance is calculated to decrease by about 0.1 A from the ground-state value of 3.05 A. The approximately 300 nm absorption displays a different enhancement pattern, in that resonance-enhanced Raman bands are observed at 103 and 183 cm(-1) in addition to nu(Au-Au) at 79 cm(-1) The compound exhibits intense, long-lived luminescence (in room-temperature CH(3)CN, for example, tau = 0.70 micros, phi(emission) = 0.037) with a maximum at 550-600 nm that is not very medium-sensitive. We conclude, in agreement with an earlier proposal of Mason (Inorg. Chem. 1989, 28, 4366-4369), that the lowest-energy, luminescent excited state is not (3)(dsigma --> psigma) but instead derives from (3)(d(x2-y2,xy --> psigma) excitations. We compare the Au(I)-Au(I) interaction shown in the various transitions of the [Au(2)(dmpm)(3)](ClO(4))(2) tribridged compound with previous results for solvent or counterion exciplexes of [Au(2)(dcpm)(2)](2+) salts (J. Am. Chem. Soc. 1999, 121, 4799-4803; Angew. Chem. 1999, 38, 2783-2785; Chem. Eur. J. 2001, 7, 4656-4664) and for planar, mononuclear Au(I) triphosphine complexes. It is proposed that the luminescent state in all of these cases is very similar in electronic nature.     

Mercury(II) cyanide coordination polymer with dinuclear gold(I) amidinate. Structure of the 2-D [Au2(2,6-Me2-formamidinate)2].2Hg(CN)2.2THF complex

The dinuclear gold(I) amidinate complex [Au(2)(Me(2)-form)(2)], 1, (Me(2)-form = 2,6-Me(2)-formamidinate) reacts with Hg(CN)(2) to form a 2D structure, 1.2Hg(CN)(2).2THF. Each gold center interacts with two Hg(CN)(2) molecules. The Au...Au distance increases from 2.7 Angstroms in the starting dinuclear complex to 2.9 Angstroms in the adduct. The gold centers are connected to four nitrogen atoms with Au-N distances in the range 2.13-2.51 Angstroms. The cyanide stretch is shifted from 2192 cm(-1) in the Hg(CN)(2) to 2147 cm(-1) in the adduct.     

Syntheses, structures, and photophysical properties of mono- and dinuclear sulfur-rich gold(I) complexes

The dinuclear gold complexes [{Au(PPh 3)} 2(mu- dmid)] ( 1) ( dmid = 1,3-dithiole-2-one-4,5-dithiolate) and [{Au(PPh 3)} 2(mu- dddt)] ( 2) ( dddt = 5,6-dihydro-1,4-dithiine-2,3-dithiolate) were synthesized and characterized by X-ray crystallography. Both complexes exhibit intramolecular aurophilic interactions with Au...Au distances of 3.1984(10) A for 1 and 3.1295(11) A for 2. A self-assembly reaction between 4,5-bis(2-hydroxyethylthio)-1,3-dithiole-2-thione ( (HOCH 2 CH 2 ) 2 dmit) and [AuCl(tht)] affords the complex [AuCl{ (HOCH 2 CH 2 ) 2 dmit}] 2 ( 4), which possesses an antiparallel dimeric arrangement resulting from a short aurophilic contact of 3.078(6) A. This motif is extended into two dimensions due to intra- and intermolecular hydrogen bonds via the hydroxyethyl groups, giving rise to a supramolecular network. Three compounds were investigated for their rich photophysical properties at 298 and 77 K in 2-MeTHF and in the solid state; [Au 2(mu- dmid)(PPh 3) 2] ( 1), [Au 2(mu- dddt)(PPh 3) 2] ( 2), and [AuCl{( HOCH 2 CH 2 ) 2 dmit}] ( 4). 1 exhibits relatively long-lived LMCT (ligand-to-metal charge transfer) emissions at 298 K in solution (370 nm; tau e approximately 17 ns, where M is a single gold not interacting with the other gold atom; i.e., the fluxional C-SAuPPh 3 units are away from each other) and in the solid state (410 nm; tau e approximately 70 mus). At 77 K, a new emission band is observed at 685 nm (tau e = 132 mus) and assigned to a LMCT emission where M is representative for two gold atoms interacting together consistent with the presence of Au...Au contacts as found in the crystal structure. In solution at 77 K, the LMCT emission is also red-shifted to 550 nm (tau e approximately 139 mus). It is believed to be associated to a given rotamer. 2 also exhibits LMCT emissions at 380 nm at 298 K in solution and at 470 nm in the solid state. 4 exhibits X/MLCT emission (halide/metal to ligand charge transfer) where M is a dimer in the solid state with obvious Au...Au interactions, resulting in red-shifted emission band, and is a monomer in solution in the 10 (-5) M concentration (i.e., no Au...Au interactions) resulting in blue-shifted luminescence. Both fluorescence and phosphorescence are observed for 4.     

Luminescence and mesogenic properties in crown-ether-isocyanide or carbene gold(I) complexes: luminescence in solution, in the solid, in the mesophase, and in the isotropic liquid state

A crown ether isocyanide CNR (R = benzo-15-crown-5) has been synthesized by dehydration of the corresponding formamide. Substitution reactions with the appropriate gold(I) precursors afford the luminescent mononuclear derivatives [AuX(CNR)] (X = Cl, C 6F 5, Br, I), [Au(C 6F 4OCH 2C 6H 4OC nH 2 n+1 - p)(CNR)] ( n = 4, 8, 10, 12), and [Au(C 6F 4OCH 2C 6H 2-3,4,5-(OC n H 2 n+1 ) 3(CNR)] ( n = 4, 8, 12). X-ray diffraction studies of [AuCl(CNR)] show the molecules associated in a tetranuclear manner with an antiparallel orientation and gold-gold distances of 3.420 and 3.427 A (Au...Au...Au angles are 121.2 degrees ). These tetranuclear units generate infinite zigzag chains through longer Au...Au distances of 3.746 A and weak C-H...O nonclassic interactions. Nucleophilic attack to the coordinated isocyanide in [AuCl(CNR)] by methanol or a primary amine produces the carbene derivatives [AuCl{C((NHR)(OMe)}] and [AuCl{C(NHR')(NHR)}] (R' = Me, n-Bu). The ether crown in these complexes is able to coordinate sodium from NaClO 4, affording the corresponding bimetallic complexes (Na/Au = 1:1). The derivatives containing one alkoxy chain are liquid crystals, displaying a smectic C mesophase (for n > 4), whereas the trialkoxy derivatives display unidentified or smectic C mesophases, depending on the alkyl chain length. After complexation of sodium salts, the mesogenic behavior is lost. All of the derivatives are luminescent at room temperature in the solid state with emission maxima in the range 405-550 nm; they emit at 77 K from 410 to 572 nm. Only the ligand and the fluoroaryl complexes emit in solution at room temperature, but all of the compounds are luminescent at 77 K. Very interestingly, some fluoroaryl derivatives with alkoxy chains are luminescent not only in the solid, and in solution, but also in the mesophase, and in the isotropic liquid at moderate temperatures. These are the first metal complexes ever reported to show luminescence in the isotropic liquid state.     

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.     

Mononuclear, dinuclear, and hexanuclear goldI complexes with (aza-15-crown-5)dithiocarbamate

The reactions of sodium (aza-15-crown-5)dithiocarbamate with [AuClL] precursors lead to mono-, di-, or hexanuclear derivatives depending on L. The homoleptic hexanuclear gold(I) cluster [Au6(S2CNC10H20O4)6] is formed by displacement of the chloride and isocyanide ligands in [AuCl(CN(2,6-Me2C6H3))]. X-ray diffraction studies show a novel geometry in gold cluster chemistry where the six gold atoms display a cyclohexane-like geometry in a chair conformation with Au-Au-Au angles of 117.028(9) degrees, two short gold-gold distances of 2.9289(5) A, and bidentate bridging dithiocarbamate ligands. The molecular structure shows a crown of gold atoms surrounded by crown ethers. This derivative luminesces at 569 nm at room temperature in the solid state. A dinuclear isomer [Au2(S2CNC10H20O4)2] had been reported previously and was obtained by reaction with [AuCl(SMe2)]. The mechanism to obtain the hexanuclear derivative involves a mononuclear intermediate [Au(S2CNC10H20O4)(CNR)] for which the X-ray structure shows a short gold-gold distance of 3.565 A with the two molecules in an anti configuration. Phosphine gold(I) mononuclear derivatives [Au(S2CNC10H20O4)(PR3)] (R = Me, Ph, both characterized by X-ray diffraction) and dinuclear diphosphine derivatives [{Au(S2CNC10H20O4)}2(mu-P-P)] (P-P = dppm, bis(diphenylphosphinomethane); dppp, 1,3-bis(diphenylphosphinopropane); and dppf, 1,1'-bis(diphenylphosphinoferrocene)) are also reported. In the mononuclear complexes, the molecular structure confirms that the dithiocarbamato ligand is mainly acting as monodentate, with a second longer Au-S distance of 3.197 (PMe3), 2.944(4) (PPh3), and 2.968 A (CNR). Three phosphine complexes are emissive at 562 (PMe3), 528 (PPh3), and 605 nm (dppm), at 77 K. X-ray diffraction studies of the dppm derivative show gold-gold intramolecular contacts of 3.0972(9) A (3.2265(10) A for a second independent molecule) and basically monodentate coordination of the dithiocarbamato ligands. All the complexes extract sodium and potassium salts from aqueous solutions. The diphosphine derivatives are noticeably better extractors than the monophosphino derivatives, mainly for potassium salts.     

Synthesis, structural characterization, and theoretical studies of gold(I) and gold(I)-gold(III) thiolate complexes: quenching of gold(I) thiolate luminescence

The gold(I) thiolate complexes [Au(2-SC6H4NH2)(PPh3)] (1), [PPN][Au(2-SC6H4NH2)2] (2) (PPN = PPh3=N=PPh3), and [{Au(2-SC6H4NH2)}2(mu-dppm)] (3) (dppm = PPh2CH2PPh2) have been prepared by reaction of acetylacetonato gold(I) precursors with 2-aminobenzenethiol in the appropriate molar ratio. All products are intensely photoluminescent at 77 K. The molecular structure of the dinuclear derivative 3 displays a gold-gold intramolecular contact of 3.1346(4) A. Further reaction with the organometallic gold(III) complex [Au(C6F5)3(tht)] affords dinuclear or tetranuclear mixed gold(I)-gold(III) derivatives with a thiolate bridge, namely, [(AuPPh3){Au(C6F5)3}(mu2-2-SC6H4NH2)] (4) and [(C6F5)3Au(mu2-2-SC6H4NH2)(AudppmAu)(mu2-2-SC(6)H4NH2)Au(C6F5)3] (5). X-ray diffraction studies of the latter show a shortening of the intramolecular gold(I)-gold(I) contact [2.9353(7) or 2.9332(7) A for a second independent molecule], and short gold(I)-gold(III) distances of 3.2812(7) and 3.3822(7) A [or 3.2923(7) and 3.4052(7) A] are also displayed. Despite the gold-gold interactions, the mixed derivatives are nonemissive compounds. Therefore, the complexes were studied by DFT methods. The HOMOs and LUMOs for gold(I) derivatives 1 and 3 are mainly centered on the thiolate and phosphine (or the second thiolate for complex 2), respectively, with some gold contributions, whereas the LUMO for derivative 4 is more centered on the gold(III) fragment. TD-DFT results show a good agreement with the experimental UV-vis absorption and excitation spectra. The excitations can be assigned as a S --> Au-P charge transfer with some mixture of LLCT for derivative 1, an LLCT mixed with ILCT for derivative 2, and a S --> Au...Au-P charge transfer with LLCT and MC for derivative 3. An LMCT (thiolate --> Au(III) mixed with thiolate --> Au-P) excitation was found for derivative 4. The differing nature of the excited states [participation of the gold(III) fragment and the small contribution of sulfur] is proposed to be responsible for quenching the luminescence.     

Syntheses of mixed-ligand tetranuclear gold(I)-nitrogen clusters by ligand exchange reactions with the dinuclear gold(I) formamidinate complex Au(2)(2,6-Me2Ph-form)2

The reaction of the sterically crowded dinuclear gold(I) amidinate complex Au2(2,6-Me2Ph-form)2, 1, with the less bulky bidentate nitrogen ligands results in the formation of tetranuclear gold(I) complexes. When the less bulky amidinate, K(4-MePh-form), A, was reacted with 1 in a 1:1 stoichiometric ratio, crystals containing equal amounts of the tetranuclear and dinuclear gold(I) aryl formamidinates, Au4(4-MePh-form)4 and Au2(2,6-Me2Ph-form)2, where 2,6-Me2Ph-form = B, were found in the same unit cell, 2 x 2THF: space group P, a = 10.794(11) A, b = 14.392(15) A, c = 25.75(3) A, alpha = 82.564(17) degrees, beta = 85.443(18) degrees, gamma = 82.614(19) degrees. The reaction of K(4-MePh-form), A, and 1 in a 1:2 ratio (excess) produced the tetranuclear complex only, 3. The potassium salt of the exchanged bulky ligand, K(2,6-Me2Ph-form), formed as a byproduct. The reaction of the dinuclear gold(I) complex Au2(2,6-Me2Ph-form)2 with the 3,5-diphenylpyrazolate salt, K(3,5-Ph2pz), resulted in the formation of two tetranuclear mixed-ligand complexes, Au4(3,5-Ph2pz)2(2,6-Me2Ph-form)2 x 2THF, 4 x 2THF (space group P21/c, a = 11.5747(19) A, b = 25.497(4) A, c = 21.221(3) A, beta = 96.979(3) degrees) and Au4(3,5-Ph2pz)3(2,6-Me2Ph-form) x THF, 5 x THF (space group P21/c, a = 23.058(5) A, b = 14.314(3) A, c = 18.528(4) A, beta = 90.94(3) degrees. The block crystals from the tetranuclear complex, 4 x 2THF, contain mixed ligands with each pyrazolate ring facing an amidinate ring. The tetranuclear mixed ligand complex, 5 x THF, was isolated as needles with ligands alternating above and below the Au4 plane. The two tetranuclear mixed-ligand complexes emit at 490 and 530 nm, respectively, under UV excitation.