Bianca Rosa Pietroni

Reactions of C-imidazolyllithium derivatives with Group Ib compounds: Tris[μ-(1-alkylimidazolato-N3,C2)]tri-gold(I) and -silver(I). Crystal structure of bis(1-benzylimidazolin-2-yliden)gold(I) chloride

Abstract Upon reaction of LMX (M  Au, X  Cl, L  PPh3 or Me2S; M  Ag, X  NO3, L  Me2S) with 1-R-2-lithiumimidazole the lithium is replaced by a noble metal to give the species (1-R-2-M-imidazole)n (M  Au, R  methyl or benzyl, n = 3; M  Ag, R = benzyl). From Me2SCuBr the compound bis(1-R-imidazol-2-yl) was obtained (R = methyl or benzyl). The unexpected formation during work up of [Au( CN(CH 2 Ph)CHCHN H)2]Cl, a carbene derivative, was confirmed by an X-ray crystal structural study which showed the presence of two independent molecules where CAuC is 175.2(4) or 176.6(4)°, average AuC is 2.027(7) A, and there is an Au ··· Au interaction at 3.2630(5) A.

Luminescent Chains Formed from Neutral, Triangular Gold Complexes Sandwiching TlI and AgI. Structures of {Ag([Au(μ-C2,N3-bzim)]3)2}BF4·CH2Cl2, {Tl([Au(μ-C2,N3-bzim)]3)2}PF6·0.5THF (bzim = 1-Benzylimidazolate), and {Tl([Au(μ-C(OEt)═NC6H4CH3)]3)2}PF6·THF, with MAu6 (M = Ag+, Tl+) Cluster Cores

It has been found that several trinuclear complexes of AuI interact with silver and thallium salts to intercalate Ag+ and Tl+ cations, thereby forming chains. The resulting sandwich clusters center the cations between the planar trinuclear moieties producing structures in which six AuI atoms interact with each cation in a distorted trigonal prismatic coordination. The resultant (B3AB3B3AB3)∞ pattern of metal atoms also shows short (∼3.0 Å) aurophilic interactions between BAB molecular centers. These compounds display a strong visible luminescence, under UV excitation, which is sensitive to temperature and the metal ion interacting with the gold. X-ray crystal structures are reported for Ag([Au(μ-C2,N3-bzim)]3)2BF4·CH2Cl2 (P [Formula: see text] , Z = 2, a = 14.4505(1)Å; b = 15.098(2)Å; c = 15.957(1)Å; α = 106.189(3)°; β = 103.551(5)°; γ = 101.310(5)°); Tl([Au(μ-C2,N3-bzim)]3)2PF6·0.5C4H8O (P [Formula: see text] , Z = 2, a = 15.2093(1)Å; b =15.3931(4)Å; c = 16.1599(4)Å; α = 106.018(1)°; β = 101.585(2)°; γ=102.068(2)°); and Tl([Au(μ-C(OEt)═NC6H4CH3)]3)2PF6·C4H8O (P2(1)/n, Z = 4, a = 16.4136(3)Å; b = 27.6277(4)Å; c = 16.7182(1)Å; β = 105.644(1)°). Each compound shows that the intercalated cation, Ag+ or Tl+, coordinates to a distorted trigonal prism of six AuI atoms. The counteranions reside well apart from the cations between the cluster chains.

Reactions of (tertiary phosphine)gold(I) substituted imidazoles or pyrazolones with acidic reagents: protonation, zole displacement, and adduct formation. Crystal structure determination of the adduct 1-methyl-2-(cyclohexylphosphinegoldthiolato)imidazole · 2benzimidazole

Abstract Imidazole (QH) or pyrazolone (Q′H2) in QAuL or (LAu)2Q′ (where L is a tertiary phosphine) is displaced by some acidic reagents HZ, where HZ = terminal acetylene, imide, thiol, dithio acid, or HI, to give ZAuL. If Z− is not a soft ligand an adduct between the ragents is obtained, and this is formulated as a protonated species, e.g. [LAuQH]+Z− (HZ = picric acid). In other cases the adduct is LAuZ · HQ (rather than LAuQ · HZ or a protonated species), in which the displaced QH is hydrogen-bonded to the product, as shown by the crystal structure of the adduct 1-methyl-2(cyclohexylphosphinegoldthiolato)imidazole sd 2benzimidazole. In this species gold(I) is two-coordinated (PAuS 172.0(1)), with AuP and AuS 2.292(3) and 2.331(3) A, respectively; the first benzimidazole is hydrogen-bonded to N(3) of the imidazole, and the second benzimidazole to the N(3) of the first, the inter-diazole N⋯HN distance being 2.81 and 2.86(1) A, respectively.

Reactions of symmetric C-imidazolylgold(I) leading to Au1 carbene complexes or mixed valence or AuIII imidazolyl derivatives. Crystal structure of [1-benzyl-3-(carboethoxy)imidazolin-2-yliden]chlorogold(I)

Reaction of trimeric 1-benzyl-2-gold(I)-imidazole, Au3im3 (im  [μ-(N1-benzyl)imidazolato-N3,C2]) with XY reagents gives either gold(I) mononuclear carbene derivatives, XAuCNRCHCHNY (Y−X = Et-I or EtO(O)CCl) or trinuclear mixed valence or gold(III) compounds. The gold(III) complexes, [(X)(Y)Au]3im3, are formed by addition of X–Y (benzoyl or p-tosyl chloride) or by reaction with thionyl chloride. With iodine and with Me3SiI, Au3im3I2 and Au3im3I4, respectively, are formed. The crystal structure of ClAuCN(CH2Ph)CHCHNCOOEt has been determined.

Dinuclear gold(I) and silver(I) derivatives with bridging phosphines containing an imidazole ring; X-ray crystal structure of (1-benzyl-2-imidazolyl)diphenylphosphinegold(I)chloride.

Abstract (1-Benzyl-2-imidazolyl)diphenylphosphine [(BzIm)Ph 2 P] can act as a monodentate or bidentate ligand to afford mononuclear (BzIm)Ph 2 PAuCl ( I ) or dinuclear [μ-(BzIm)Ph 2 PAu] 2 2+ 2X − (X = PF 6 − , BF 4 − or NO 3 − ) ( IIa,b,c ) derivatives of gold(I). Analogous dinuclear silver(I) derivatives were obtained reacting the ligand [(BzIm)Ph 2 P] with AgX salts (X = NO 3 − , BF 4 − ) ( IIIa,b ). In solution the silver complexes show a fluxional behaviour, and two conformers were observed by 31 P NMR spectroscopy. The structure of compound I was established by X-ray crystallography (monoclinic, space group C2/c, a = 18.068(2), b = 16.576(2), c = 15.391(2) A , β = 117.2(2)°, Z = 8) . The short intermolecular Au⋯Au distance of 3.03(2) A indicates a metal-metal interaction. The 197 Au Mossbauer parameters of compounds I and IIa are consistent with IR, NMR and crystallographic data.

A 197Au mössbauer study of reaction products of trimeric 1-benzyl-2-gold(I)-imidazole leading to AuI carbene or AuI imidazoline complexes and trinuclear AuIII imidazolyl derivatives. X-Ray crystal structure of [{(μ-1-benzylimidazolato-N3,C2)Au}3I2]

Reactions of the trinuclear [Au3Rim3] compound (Rim = [μ-1-benzylimidazolato-N3,C2] with several reagents capable of oxidative addition have been investigated by 197Au Mossbauer spectroscopy. The reaction products are either AuI carbene mononuclear and binuclear complexes or trinuclear AuIII and mixed-valence compounds. The X-ray crystal structure of the mixed-valence complex [AuIIIAuI2Rim3I2] has been determined. Two two-coordinate AuI centres show average AuC and AuN distances of 2.02(3) and 2.04(2) A and average CAuN angles of 175.0(1.2)°, whereas the four-coordinate AuIII centre gives AuC and AuN 1.96(4) and 1.91(3) A with the CAuN angle 170.5(1.6)°, and AuI average distances 2.598(3) A, with an IAuI angle 175.8(1)°. The AuAu intramolecular distances [Au(1) ⋯ Au(2) 3.432(3), Au(1) ⋯ Au(3) 3.508(3), Au(2) ⋯ Au(3) 3.464(3) A] indicate a weak metal-metal interaction.

Reactions of trimeric 1-benzyl-2-gold(I)imidazole leading to AuI carbene complexes. Crystal structure of [1-benzyl-3-benzoyl-imidazolin-2-yliden]chlorogold(I)☆

Abstract The crystal structure determination of a compound previously described as tris-[{μ-(N1-benzyl)imidazolato-N3,C2}(chloro)benzoylgold(III)], which turned out to be a gold(I) mononuclear carbene derivative, has led to a reconsideration of the reactions of [Au3 (im3 = μ-(N1-benzyl)imidazolato-N3,C2) with reagents X–Y. The mononuclear or trinuclear nature of other Au imidazolyl derivatives is discussed and the compounds obtained by reaction with X–Y = ClCOOEt, IEt or Cl-p-tosyl and chlorobenzoyl appear to be mononuclear, whereas those obtained by reaction with Me3SiI, SOCl2 or I2 appear to be trinuclear mixed valence or gold(III) compounds.

Solid state and solution structural studies of silver(I) cyclic complexes bearing the (Bzim)Ph2P ligand

Cyclic silver(I) compounds having a [μ-(Bzim)Ph 2 PAg] 2 2+ unit ((Bzim)Ph 2 P=1-benzyl-2-imidazolyldiphenylphosphine) and NO 3 − ( I ), BF 4 − ( II ), and B[3,5-(CF 3 ) 2 C 6 H 3 ] 4 − ( III ) as counterions were characterized in the solid state by X-ray crystal structure determinations ( I , II ), and in solution by 1 H-, 13 C-, 19 F- and 31 P-NMR spectroscopies. The crystal structure of complex [μ-(Bzim)Ph 2 PAg(NO 3 )] n ( n =2, 4) ( I ) (triclinic, space group P 1 (no. 2), a =15.118(5), b =17.755(3), c =14.123(4) A, α =90.23(2), β =111.67(2), γ =85.92(2)°, Z =2) shows two conformers A and B in the unit cell. The conformer A consists of a tetranuclear species formed by two [μ-(Bzim)Ph 2 PAg] 2 2+ moieties, related by a center of symmetry, bonded together by two bridging nitrate anions. The nitrate anions are coordinated to the silver atoms in an unusual fashion. The conformer B is a dinuclear species where the silver atoms present in the eight-membered ring complete their tetracoordination with two chelate nitrate anions. The crystal structure of complex {[μ-(Bzim)Ph 2 PAg(BF 4 )] 2 } ∞ ( II ) (monoclinic, space group P 2 1 / c (no. 14), a =11.563(3), b =8.353(4), c =26.188(7) A, β =95.88(2)°, Z =2) consists of infinite chains of the dinuclear cyclic silver moieties held together by BF 4 − bridging anions. The low temperature experimental and simulated 31 P-NMR spectra of complexes I – III show complex apparent doublets of multiplets due to the resonance of the spin systems of the three isotopomers of the silver atoms present in the cyclic units. The interionic solution structure of complex II was investigated by 19 F{ 1 H}-HOESY NMR spectroscopy. In methylene chloride solution the BF 4 − anion is not more coordinated to the silver(I) atoms as in the solid state, and it is localized in between the phenyl and benzyl groups of the ligand.

(Tertiary phosphine)gold(I) derivatives of 2-pyridones

Abstract Reaction of (R 3 P)AuCl with some 1-unsubstituted 2-pyridones and alkali in homogeneous or heterogeneous medium has given (R 3 P)AuQ compounds (QH is 2-pyridone, 3-nitro-, 5-chloro-, or 6-methyl-pyridone; R is t-Bu, cyclo-hexyl, phenyl, or 1-naphthyl). Combined infrared and NMR evidence indicates that the compounds are derived from the 2-pyridone tautomer, the metal being in the 1-position. An X-ray crystal structure determination carried out on Ph 3 PAu(6-methylpyridonato- N )· H 2 O· 0.5C 6 H 6 , the first structural analysis on a derivative in which the Q ligand is monodentate, reveals that the pyridonato- N ligand is derived from the keto-tautomer, the CO distance being 1.23(2) A, and that the coordination around the gold atom is approximately linear (PAuN 173.4(3)°). with AuN 2.077(9), AuP 2.236(3) A and no metal-metal interaction.

Reactivity of bis(diphenylphosphines)digold(I) dications with azotate neutral heterocycles: X-ray crystal structure of eclipsed [μ-dppmAu2(pzH)2]2+ · 2ClO4− · H2O and staggered [μ-dppeAu2(pzH)2]2+ · 2ClO4− complexes

Dinuclear gold(I) dicationic complexes were prepared reacting [ μ -dpp(CH 2 ) n Au 2 ] 2+ (dpp(CH 2 ) n =bis(diphenylphosphine)alkane; n =1, 2, 3) with azotate neutral heterocycles. Using 3,5-dimethylpyrazole (pzH) as ancillary ligand and ClO 4 − as counterion, insoluble polymeric species were obtained by a kinetic control of the reactions; extractions by hot chloroform yield the corresponding monomeric derivatives [ μ -dpp(CH 2 ) n Au 2 (pzH) 2 ] 2+  · 2ClO 4 − ( I , IIa , III ). In one case using NO 3 − instead of ClO 4 − anion the monomeric specie ( IIb ) was directly obtained. Using as neutral coordinating ligand bis(imidazo-2-yl)methane (BIMH 2 ), ten- and 11-membered heterobridged cyclic derivatives [ μ -dpp(CH 2 ) n Au 2 μ -BIMH 2 ] 2+  · 2ClO 4 − ( IV , V ) were also obtained. 31 P-NMR spectrum of ( IV ) revealed partial and complete opening of the cycle in solution. The X-ray crystal structures of [ μ -dppmAu 2 (pzH) 2 ] 2+  · 2ClO 4 −  · H 2 O ( I ) and [ μ -dppeAu 2 (pzH) 2 ] 2+  · 2ClO 4 − ( IIa ) are reported (( I ): monoclinic, space group P 2 1 / n , a =12.253(4), b =19.417(3), c =19.152(2) A, β =97.90(2)°, Z =4; ( IIa ): monoclinic, space group P 2 1 / n , a =10.997(3), b =13.629(2), c =14.812(2) A, β =104.63(1)°, Z =2). The short intramolecular Au⋯Au distance of 3.133(2) A found in complex ( I ) indicates a metal–metal interaction.