Josefina Jiménez

Gold complexes with heterocyclic thiones as ligands. X-Ray structure determination of [Au(C5H5NS)2]ClO4

Displacement of the weakly co-ordinating tetrahydrothiophene (tht) ligand in [AuX(tht)], [Au(tht)2]ClO4, or [Au(PPh3)(tht)]ClO4(X = Cl or C6F5) by heterocyclic thiones HL (HL = C3H5NS2, C4H4N2S, C5H5NS, C7H5NS2, or C7H6N2S), leads to the formation of neutral or cationic complexes of the types [AuX(HL)], [Au(HL)2]ClO4, or [Au(PPh3)(HL)]ClO4. For gold(III) complexes the tht ligand cannot be displaced but [Au(C6F5)3(OEt2)] reacts with HL to give neutral complexes [AuR3(HL)]. Deprotonation of the NH unit in the cationic complexes leads to neutral monomeric complexes and since the deprotonated N atom is now a donor, binuclear complexes can be prepared by displacement of a weakly co-ordinating ligand from other suitable complexes. The structure of [Au(HL)2]ClO4(HL = C5H5NS) has been established by X-ray crystallography [space group P, a= 9.609(3), b= 15.024(6), c= 16.712(7)A, α= 97.52(4), β= 104.17(2), γ= 104.76(2)°, and R′= 0.045 for 5 499 unique observed reflections]. The cations are arranged in a way that is unprecedented for gold(I) compounds. Five of the six cations in the cell are linked by short Au ⋯ Au contacts (3.3 A) and the sixth cation is monomeric.

Mesitylgold complexes: synthesis and reactivity; crystal structure of [{(Ph3P)Au(µ-mes)Ag(tht)}2][SO3CF3]2(mes = mesityl, tht = tetrahydrothiophene)

The complex [AuCl(AsPh3)] reacted with MgBr(mes)(mes = mesityl) to give the corresponding gold(I) derivative [Au(mes)(AsPh3)], which undergoes substitution reactions with neutral ligands to give the neutral complexes [Au(mes)L](L = Ph2PCH2PPh2, PPh3 or PPh2Me) or with QX to afford anionic complexes Q[Au(mes)X][X = Cl. Q = P(CH2Ph)Ph3; X = Br, Q = N(PPh3)2]. The latter reacted with X2(X = Cl or Br) to give gold(III) complexes, Q[Au(mes)X3][X = Cl, Q = P(CH2Ph)Ph3; X = Br, Q = N(PPh3)2]. The reaction of [Au(mes)(PPh3)] with [Ag(OSO2CF3)L][L = PPh3 or tetra-hydrothiophene (tht)] afforded [{(Ph3P)Au(µ-mes)AgL}n][SO3CF3]n(L = PPh3, n= 1; L = tht, n= 2). The structure of [{(Ph3P)Au(µ-mes)Ag(tht)}2][SO3CF3]2 has been determined by a single-crystal X-ray diffraction study, which shows an Au–Ag distance of 2.8245(6)A.

Syntheses of dinuclear gold(I) ring complexes containing two different bridging ligands. Crystal structure of [Au2{µ-(CH2)2PPh2}(µ-S2CNEt2)]

The reaction of [Au2{µ-(CH2)2PPh2}2] with [Au2(µ-L–L)2]n+[n= 0, L–L = S2CNMe2, S2CNEt2 or S2CN(CH2Ph)2; n= 2, L–L = Ph2PCH2PPh2(dppm), Ph2P(CH2)2PPh2 or Ph2PNHPPh2] led to heterobridged dinuclear complexes [Au2{µ-(CH2)2PPh2}(µ-L–L)]n+(n= 0 or 1). The same complexes can also be obtained by reaction of [N(PPh3)2][(AuCl)2{µ-(CH2)2PPh2}] with the silver compounds [Ag(S2CNMe2)]6 or [Ag2(OClO3)2(dppm)3] or by reaction of [(AuPPh3)2{µ-(CH2)2PPh2}][ClO4] with [{Au(C6F5)}2(µ-L–L)](L–L = diphosphines or o-Ph2PC5H4N). The structure of [Au2{µ-(CH2)2PPh2}(µ-S2CNEt2)] has been established by X-ray crystallography. Two molecules are bonded through an intermolecular gold–gold interaction, thus forming a linear chain of four gold atoms with Au–Au (intramolecular) 2.867, 2.868, (intermolecular) 2.984 A.

New liquid crystalline materials based on two generations of dendronised cyclophosphazenes

A divergent approach was used for the synthesis of dendritic structures based on a cyclotriphosphazene core with 12 or 24 hydroxyl groups, by starting from [N(3)P(3)(OC(6)H(4)OH-4)(6)] and using an acetal-protected 2,2-di(hydroxymethyl)propionic anhydride as the acylating agent. Hydroxyl groups in these first- and second-generation dendrimers, G1-(OH)(12) or G2-(OH)(24), were then condensed in turn with mono- or polycatenar pro-mesogenic acids to study their ability to promote self-assembly into liquid crystalline structures. Reactions were monitored by using (31)P{(1)H} and (1)H NMR spectroscopy and the chemical structure of the resulting materials was confirmed by using different spectroscopic techniques and mass spectrometry (MALDI-TOF MS). The results were in accordance with monodisperse, fully functionalised cyclotriphosphazene dendrimers. Thermal and liquid crystalline properties were studied by using optical microscopy, differential scanning calorimetry and X-ray diffraction. The dendrimer with 12 4-pentylbiphenyl mesogenic units gives rise to columnar rectangular organisation, whereas the one with 24 pentylbiphenyl units does not exhibit mesomorphic behaviour. In the case of materials that contain polycatenar pro-mesogenic units with two aromatic rings (A4 vs. A5), the incorporation of a short flexible spacer connected to the periphery of the dendron (acid A5) was needed to achieve mesomorphic organisation. In this case, both dendrimer generations G1 A5 and G2 A5 exhibit a hexagonal columnar mesophase.

Luminescent iminophosphorane gold, palladium and platinum complexes as potential anticancer agents

A series of coordination gold(III), palladium(II), and platinum(II) complexes with a luminescent iminophosphorane ligand derived from 8-aminoquinoline [Ph3P=N-C9H6N] (1), have been synthesized and structurally characterized. The coordination palladium(II) and platinum(II) compounds can evolve further, under appropriate conditions, to give stable cyclometalated endo species [M{κ3-C,N,N-C6H4(PPh2=N-8-C9H6N}Cl] (M = Pd, Pt) by C-H activation of the phenyl group of the PPh 3 fragment. Iminophosphorane 1 and the new metallic complexes are luminescent in DMSO or DMSO:H2O (1:1 mixture) solutions at RT. The compounds have been evaluated for their antiproliferative properties in a human ovarian cancer cell line (A2780S), in human lung cancer cells (A-549) and in a non-tumorigenic human embryonic kidney cell line (HEK-293T). Most compounds have been more toxic to the ovarian cancer cell line than to the non-tumorigenic cell line. The new complexes interact with human serum albumin (HSA) faster than cisplatin. Studies of the interactions of the compounds with DNA indicate that, in some cases, they exert anticancer effects in vitro based on different mechanisms of action with respect to cisplatin.

Alternative synthesis of binuclear gold(II) ylide complexes: cationic gold(II) complexes. X-Ray crystal structures of [{Au(CH2)2PPh2}2Br2] and [{Au(CH2)2PPh2}2(PPh3)2][CLO4]2

The complex [{Au(CH2)2PPh2}2Cl2] reacts with silver salts AgX to give the corresponding gold(II) derivatives [{Au(CH2)2PPh2}2X2](X = C6F5, C6H2F3–2, 4, 6, NO3 or MeCO2), whilst reaction with suitable silver complexes [AgX′(L)][X′= ClO4, L = tetrahydrothiophene (tht) or PPh3; X′= NO3, L = PMe3] gives cationic gold(II) derivatives [{Au(CH2)2PPh2}2L2]X′2, which either undergo metathetical reactions with MX [X = Br, SCN or S2CN(CH2Ph)2] to give other neutral complexes inaccessible by the first procedure or react with neutral ligands L′ to afford other cationic complexes [L′= pyridine (py), AsPh3 or SbPh3]. The structures of [{Au(CH2)2PPh2}2Br2] and [{Au(CH2)2PPh2}2(PPh3)2][ClO4]2 have been established by single-crystal X-ray diffraction studies.

2,4,6-Trifluorophenyl gold(I) and gold(III) complexes

Abstract Displacement of tetrahydrothiophen (tht) from AuR(tht) (R = 2,4,6-C6F3H2) by anionic ligands gives [AuRX]−, which reacts with AgClO4 or AgR to give [AuR]4, [RAuSCNAuR]− or [AuAgR2]x. Neutral [AuR3L (L = PPh3, AsPh3, SbPh3, OPPh3, SPPh3, NCMe, NCPr, NCPh, NC(CHCH2), o-(NC)2C6H4 or py), (μ-4,4′-bipy)AuR3 or cis-AuR2Cl(py)], anionic {(NBu4)[AuR3Br] or (NBu4)[AuR4]} or cationic {trans-[AuR2(4,4′-bipy)]ClO4} gold(III) complexes are obtained by displacement of the ether ligand of AuR3(OEt2), AuR2Cl(OEt2) or [AuR2(OEt2)2] ClO4.

Metallophosphazene precursor routes to the solid-state deposition of metallic and dielectric microstructures and nanostructures on Si and SiO2.

We present a method for the preparation and deposition of metallic microstructures and nanostructures deposited on silicon and silica surfaces by pyrolysis in air at 800 degrees C of the corresponding metallophosphazene (cyclic or polymer). Atomic force microscopy studies reveal that the morphology is dependent on the polymeric or oligomeric nature of the phosphazene precursor, on the preparation method used, and on the silicon substrate surface (crystalline or amorphous) and its prior inductively couple plasma etching treatment. Microscale and nanoscale structures and high-surface-area thin films of gold, palladium, silver, and tin were successfully deposited from their respective newly synthesized precursors. The characteristic morphology of the deposited nanostructures resulted in varied roughness and increased surface area and was observed to be dependent on the precursor and the metal center. In contrast to island formation from noble metal precursors, we also report a coral of SnP(2)O(7) growth on Si and SiO(2) surfaces from the respective Sn polymer precursor, leaving a self-affine fractal structure with a well-defined roughness exponent that appears to be independent (within experimental error) of the average size of the islands. The nature of the precursor will be shown to influence the degree of surface features, and the mechanism of their formation is presented. The method reported here constitutes a new route to the deposition of single-crystal metallic, oxidic, and phosphate nanostructures and thin films on technologically relevant substrates.

Asymmetric monocationic and dicationic gold(II) complexes: X-ray structure of [MePh2PAuCH2PPh2CH2)2AuOH2] (ClO4)2 · 2CH2Cl2· H2O

Abstract The reaction of [(tht)Au(CH 2 PPh 2 CH 2 ) 2 Au(tht)](ClO 4 ) 2 (tht = tetrahydrothiophene) with [Ag(OClO 3 )PR 3 ] (PR 3 = PPh 3 , PPh 2 Me or P(4-MeOC 6 H 4 ) 3 ) gives [R 3 PAu(CH 2 PPh 2 CH 2 ) 2 Au(tht)](ClO 4 ) 2 . Displacement of weakly coordinated ligands gives new dicationic ([R 3 PAu(CH 2 PPh 2 CH 2 ) 2 AuL]ClO 4 ) 2 (L=py, AsPh 3 , PPh 2 Me or OH 2 )) or monocationic complexes ([R 3 PAu (CH 2 PPh 2 CH 2 ) 2 AuX]ClO 4 (X=Cl, S 2 CN(CH 2 Ph) 2 or OClO 3 )). The structure of [MePh 2 PAu(CH 2 PPh 2 CH 2 ) 2 Au(OH 2 )]ClO 4 was confirmed by single-crystal X-ray diffraction analysis. The 197 Au Mossbauer spectra of [Ph 3 PAu(CH 2 PPh 2 CH 2 ) 2 Au(tht)](ClO 4 ) 2 is reported and compared with other symmetric or asymmetric dinuclear gold(II) complexes.