Elena Lalinde

Polymorphic Ionic Mesogens of Silver(l): Ionic Materials Exhibiting a Thermotropic Cubic Mesophase

Abstract Reaction of tran.s-4-alkyloxy-4′-stilbazoles (n-OPhVPy) with silver dodecylsulphate (AgDOS) led to the complexes [Ag(n-OPhVPy)2][DOS] which showed thermotropic mesomorphism. All homologues from methyloxy (n=1) to dodecyloxy (n=12) have been synthesised. The complexes showed a nematic phase at short chain lengths, but at longer chain lengths, smectic C and A phases were observed in addition to an isotropic mesophase (Mt), similar to the recently characterised D phase. The mesomorphism was determined using optical microscopy, DSC and X-ray scattering.

Synthesis of mono- and polynuclear perhalophenyl palladium-platinum acetylide complexes. Molecular structure of (NBu4)2[Pt2Ag2(C6F5)4(CCPh4] · 4CH2Cl2

Abstract The reaction between [Ag(CCR)]n (R = tBu, Ph) and the appropriate mononuclear palladium or platinum substrate affords mononuclear derivatives of the type [M(C6F5)(CCR)L2] (M = Pd, Pt; R = tBu, Ph; L = PPh3, dppe). Polynuclear (NBu4)2[Pt2Ag2(C6F5)4(CCPh)4] (X = F, Cl; R = Ph, tBu) complexes are obtained by reaction between (NBu4)2[Pt2(μ-X′)2(C6X5)4] (X′ = Cl, X = F; X′ = I, X = Cl) and [Ag(CCR)]n (Pt:Ag ratio 1:2). Similar heterometallic derivatives Q2[Pt2M2(C6F5)4 (CCR)4] (Q = PMePh3, NBu4; M = Ag, Cu; R = Ph, tBu) can be prepared by reaction of Q2[cis-Pt(C6F5)2(CCR)2] with AgCl or CuCl (Pt:M ratio 1:1). The structure of (NBu4)2[Pt2Ag2(C6F5)4 (CCPh)4]·4CH2Cl2 has been determined by X-ray diffraction.

Polynuclear platinum–silver, –copper, and –gold acetylide complexes. Molecular structure of [Pt2Ag4(CCBut)8]

Hexanuclear complexes [Pt2Ag4(CCR)8] [R = Ph (1) or But (2)] have been obtained by treating [PtCl2(tht)2] (tht = tetrahydrothiophene) with [Ag(CCR)]n(Pt/Ag 1 : 4). The complexes [Pt2M4(CCR)8] [M = Cu, R = Ph (3) or But (4); M = Au, R = But (5)] were obtained from [Pt2Ag4(CCR)8] with CuCl or [AuCl(tht)] respectively. Alternatively, the reactions between [NBu4]2[Pt(CCR)4] and AgClO4, CuCl–NaClO4, or [AuCl(tht)]–NaClO4 yield respectively complexes (1)–(5). The molecular structure of [Pt2Ag4(CCBut)8] has been determined by an X-ray diffraction study: monoclinic, space group C2 with a = 37.062(7), b = 12.0223(16), c = 20.459(3) A, β = 107.485(15)°, Z = 6, R 0.0416, R′ 0.0465 for 5 613 reflections with F > 6σ(F). The six metal atoms are arranged in a slightly irregular octahedron with the platinum atoms mutually trans and the silver atoms in the equatorial plane, with Pt ⋯ Ag and Ag ⋯ Ag distances longer than 3.0 A. Each platinum atom is in an almost square-planar environment formed by four CCBut ligands. Each acetylenic fragment also forms an asymmetric π interaction with one silver atom of the equatorial positions so that each silver atom is bonded to two acetylenic fragments, of two different Pt(CCBut), moieties. These moieties of each [Pt2Ag4(CCBut)8] unit are staggered.

Synthesis of novel platinum-silver and platinum-copper complexes with bridging alkynyl ligands

Abstract The study of the reactivity of [Pt 2 M 4 (CCR) 8 ] (MAg or cu; RPh or t Bu) towards different neutral and anionic ligands is reported. This study reveals that reactions of the phenylacetylide derivatives [Pt 2 M 4 (CCPh) 8 ] with anionic, X − (XCl or Br) or neutral donors (CN t Bu or py) in a molar ratio 1:4 (m/donor ratio 1:1) yield the trinuclear anionic (NBu 4 ) 2 [{Pt(CCPh) 4 (MX) 2 ] (MAg or Cu, X Cl or Br) or neutral [{Pt(CCPh0 4 =sAGL) 2 ] (LCN t Bu or py) complexes, respectively. The crystal structure of (NBu 4 ) 2 [{Pt(CCPh) 4 }(CuBr) 2 ]( 4 ) shows that the anion is formed by a dianionic Pt(CCPh) 4 fragment and two neutral CuBr units joined through bridging alkynyl ligands. All the alkynyl groups are σ bonded to Pt and η 2 -coordinated to a Cu atom which have an approximately trigonal-planar geometry. By contrast, similar reactions with [Pt 2 M 4 (CC t Bu) 8 ] (molar ratio M/donor 1:1) afford hexanuclear dianionic (NBu 4 ) 2 [Pt 2 M 4 (CC t Bu) 8 X 2 ] or neutral [Pt 2 Ag 4 (CC t Bu0 8 Py 2 ]. Only by treatment with a large exces of Br − (molar ratio M/Br − 1:2) are the trinuclear complexes (NBu 4 ) 2 [{Pt(CC t Bu 4 (MBr) 2 ] (MAg, Cu) obtained. Attempted preparations of analogous complexes with phosphines (L′PPh 3 or PEt 3 ) by reactions of [Pt 2 M 4 (CCR 8 ] with L′ leads to displacement of alkynyl ligands from platinum and formation of neutral mononuclear complexes [ trans -Pt(CCR) 2 L′ 2 ].

Synthesis of mesoporous metal complex-silica materials and their use as solvent-free catalysts

Incorporation of various Pd(II) complexes into the framework of MSU-X mesoporous silica has been achieved by co-condensation using a facile solvent-free one-pot synthesis. The use of ligands with triethoxysilyl terminal groups permitted the synthesis of three different metallosilanes precursors (metal complexes with ligands containing trialkoxysilane terminal groups), which allow for the homogeneous in situ incorporation of metal complexes covalently bonded to the porous support. Inorganic precursor tetraethylorthosilicate was used both as silica source and as solvent for the synthesis of the complexes, avoiding the use of other organic co-solvents, making the synthesis environmentally benign. The gentle synthesis conditions used such as neutral pH, room temperature and mild ethanol extraction of the surfactant, allowed a cleaner route for the immobilization of homogeneous Pd(II) catalysts in mesoporous silica, while protecting the structural and chemical integrity of the metal complexes. For comparison purposes, monomer complexes [trans-PdCl2L2] (L = NH2(CH2)3Si(OEt)3, 4-C5H4N–(CH2)2Si(OEt3), PPh2(CH2)2Si(OEt)3) were synthesized using the same aerobic reaction conditions to those use for the co-condensation processes and fully characterized before their incorporation in the mesoporous silica. The catalytic performance of these materials was tested for the Suzuki-Miyaura reaction under solvent-free conditions. Efficient mixing of all the components was accomplished by applying either magnetic stirring or ball milling. The good yields obtained, even at room temperature, confirmed the catalytic activity of the metal complexes once incorporated into the mesoporous silica framework. The possibility to work under solvent-free conditions even with solid starting reactants, is a significant step forward in the Suzuki-Miyaura coupling reaction because its benefits in terms of cost and impact of the environment.

Synthesis, structure and reactivity of homo- and hetero-polynuclear complexes of platinum bearing CCR groups as unique bridging ligands

Recent advances in the preparation of bi- or poly-nuclear platinum complexes bridged only by alkynyl ligands are described. Emphasis is placed not only on the co-ordination modes of alkynyl ligands but also on their migration and chemical activation.

Luminescent one- and two-dimensional extended structures and a loosely associated dimer based on platinum(II)-thallium(I) backbones.

Neutralization reactions between (NBu4)2[ trans-Pt(C 6F5)2(CN)2] 1 and (NBu4)2[cis-Pt(C6F5)2(CN)2] 2 with TlPF 6 have been carried out, and the resulting structures of [trans,trans,trans-Tl2{Pt(C6F5)2(CN)2}.(CH3COCH3) ] n [4.(CH3COCH3)2] n and {Tl[Tl{cis-Pt(C6F5)2(CN)2}].(H2O)} n [5.(H2O)] n have been determined by X-ray crystallography. Remarkably, the change from trans to cis geometry on the platinum substrate causes a significant decrease in the Pt(II)...Tl(I) metallophilic interaction. Thus, the platinum center in the trans fragment easily connects with two Tl(I) ions forming a distorted pseudo-octahedron PtTl2, which generates a final two-dimensional layered structure by secondary additional intermolecular Tl(I)...N(CN) interactions. However, the [cis-Pt(C6F5)2(CN)2] (2-) fragment interacts strongly with just one Tl center leading to an extended helical [-Pt-Tl-Pt-Tl-] n(n-) chain. In this case, the second thallium center neutralizes the anionic chain mainly through Tl...N(CN) ( intra) and Tl...F(C 6F 5) (intra and inter)actions. The reaction of TlPF 6 with the monoanionic fragment (NBu4)[cis-Pt(C6F5)2(CN)(PPh2C[triple bond]CPh)] 3 yields the discrete associated dimer [Tl{cis-Pt(C6F5)2(CN)(PPh2C[triple bond]CPh)}] 2 [ 6] 2. Dimer [ 6] 2 could be described as two square pyramids with the thallium atoms in the apical positions, connected through Tl...N(cyano) interactions. The final heteropolynuclear Pt-Tl complexes, except 4 at room temperature, show bright emission in the solid state when irradiated with UV-vis radiation, in contrast to the precursors 1 and 3, which are not luminescent. This difference indicates that the emissions in 4- 6 are presumably related to the interaction between the metal centers. The Pt-Tl bonding interactions and, consequently, the emissive properties are lost in solution at room temperature, as shown by the conductivity and NMR measurements. However, variable-concentration luminescence measurements in glassy acetonitrile solutions indicate the formation of different aggregates with different degrees of Pt...Tl interactions for 4 and 5 and a dimeric structure similar to that observed in solid state for 6.

Synthesis, structures and photophysics of novel luminescent platinum–copper complexes

Abstract The novel hexanuclear platinum–copper complex [Pt2Cu4(C6F5)4(CCtBu)4(acetone)2] (1) and the polynuclear derivative [PtCu2(C6F5)2(CCPh)2]x (2), which crystallises in acetone as [Pt2Cu4(C6F5)4(CCPh)4(acetone)4] (2)·(acetone)4, have been prepared using [cis-Pt(C6F5)2(THF)2] and the corresponding copper–acetylide [Cu(CCR)]x (molar ratio 1:2) as starting materials. Treatment of 1 and 2 with 2,2′-bipyridine (molar ratio Cu–bipy 1:1), afforded the new trinuclear derivatives [{cis-Pt(C6F5)2(μ-CCR)2}{Cu(bipy)}2] (R=tBu 3, Ph 4), in which the dianionic 3-platina-1,4-diyne acts as a didentate bridging ligand to two different cationic Cu(bipy) units through η2-side-on coordination of the alkynyl fragments. While similar treatment of 1 with dppe (Cu–dppe 1:1) yielded [{cis-Pt(C6F5)2(μ-CCtBu)2}{Cu(dppe)}2] (5), the analogous reaction of 2 with dppe afforded a mixture of complexes containing [Pt(C6F5)(CCPh)(dppe)] as the main platinum compound. The crystal structures of 1, 2·(acetone)4, 3 and 4 and the luminescent behaviour of all complexes have been determined. A comparison of the photoluminescent spectra of 1 and 2 with those of the related platinum–silver species [PtAg2(C6F5)2(CCR)2]x and the monomeric [cis-Pt(C6F5)2(CCR)2]2− suggests the presence of emitting states bearing a large cluster [PtM2]x-to-ligand (alkynide) charge transfer (CLCT).

Synthesis of anionic pentafluorophenyl platinum-silver acetylide complexes. Molecular structures of (NBu4[Pt(C6F5) 2(μ-CCPh)2Ag(PPh3)] and (NBu4)2[{Pt(C6F52(μ-CCPh)2Ag}2(μ-dppe)]

Abstract Heterobinuclear alkynyl-bridged complexes (NBu 4 )[Pt(C 6 F 5 ) 2 (μ-CCR) 2 AgL] (R=1cr;Ph or t Bu; L=1cr;PPh 3 or PEt 3 ) ( 1 - 4 ) are obtained by treating the anionic tetranuclear platinum-silver derivatives (NBu 4 ) 2 [Pt 2 Ag 2 (C 6 F 5 ) 4 (CCR) 4 ] (R=1cr;Ph or t Bu) with PPh 3 or PEt 3 (molar ratio 1:2 or 1:4), whereas treatment with the bidentate 1,2-bis(diphenylphosphino) ethane (dppe) (molar ratio 1:1) gives tetranuclear complexes (NBu 4 ) 2 [{Pt(C 6 F 5 ) 2 (μ-CCR) 2 Ag} 2 (μ-dppe)] (R=1cr;Ph 5 ; R=1cr; t Bu 6 ). The structures of (NBu 4 )[Pt(C 6 F 5 ) 2 (μ-CCPh) 2 AgPPh 3 ]( 1 ) and (NBu 4 ) 2 [{Pt(C 6 F 5 ) 2 (μ-CCPh) 2 A} 2 (μ-dppe)] ( 5 ) have been established by singlecrystal X-ray diffraction studies. In the solid state, the structure of the anion of complex 1 reveals that the two metal atoms [Pt⋯Ag 3.059(1) A] are asymmetrically bridged by two phenylacetylide groups, each of which forms a σ-bond to platinum and a side-on π-bond to silver. The anion of compound 5 , which possesses an inversion centre, is formed by two identical {Pt(C 6 F 5 ) 2 (μ-CCPh) 2 Ag} units connected through a dppe ligand. Each silver atom is asymmetrically π-bonded to each acetylide group and completes their trigonal coordination by bonding to a phosphorus atom of the dppe. 1 H, 19 F, 31 P NMR data indicate that all complexes exhibit dynamic behaviour in solution.

Synthesis of Novel Heterotetrametallic (d6-d10-d8) Polyalkynyl Complexes Starting from Heterobimetallic Chloride-Bridged (d6-d8) Compounds

The reaction between the half-sandwich cyclopentadienyl complexes [M(η5-C5Me5)Cl2(PEt3)] (M = Rh, Ir) and [cis-M′(C6F5)2(thf)2] (M′ = Pt, Pd; thf = tetrahydrofuran) affords the corresponding chloride-bridged heterobinuclear Rh,Ir/Pt,Pd complexes [(PEt3)(η5-C5Me5)M(μ-Cl)2M′(C6F5)2] (1−4). In contrast, similar reactions with the chloro-bridged binuclear compounds [{M(η5-C5Me5)Cl(μ-Cl)}2] (M = Rh, Ir) lead instead to the unexpected mixed salt complexes {Cp*M(μ-Cl)3MCp*}2[{(C6F5)2M′(μ-Cl)}2] (M = Rh, Ir; M′ = Pt, Pd) (5−8) as a result of chloride transfer. The structures of [(PEt3)(η5-C5Me5)Rh(μ-Cl)2Pt(C6F5)2] (1) and {Cp*Rh(μ-Cl)3RhCp*}2[{(C6F5)2Pd(μ-Cl)}2] (6) have been determined by X-ray diffraction analyses. The reactivity of the new chloride-bridged heterobinuclear compounds 1−4 towards the alkynylating agents [M′′(C≡CR)]n (M′′ = Cu, Ag) has also been investigated: a new type of tetranuclear product, [(PEt3)Cp*M(μ-1κCα:η2-C≡CPh)2M′′2(μ-4κCα:η2-C≡CPh)2Pt(C6F5)2] (M = Rh, Ir; M′′ = Cu, Ag) (9−12), was obtained, and fully characterized in the case of complex [(PEt3)Cp*Rh(μ-1κCα:η2-C≡CPh)2Cu2(μ-4κCα:η2-C≡CPh)2Pt(C6F5)2] (9).