Pablo González-Herrero

Vinylidene, Vinyl, and Carbene Ruthenium Complexes with Chelating Diphosphanes as Ligands

The ruthenium vinylidenes [RuCl2(=C=CHR)(PR′3)2] (1, 2) react with 1,2-C2H4(PCy2)2 (3) to give the chelate complexes [RuCl2(=C=CHR)(κ2-3)] (4, 5) by displacement of the two monodentate phosphane ligands. In contrast, the reaction of the hydrido compound [RuHCl(=C=CH2)(PCy3)2] (6) with excess 3 proceeds by migration of the hydride to the Cα carbon atom of the vinylidene unit and affords the six-coordinate vinyl complex trans-[RuCl(CH=CH2)(κ2-3)2] (7). Protonation of 7, followed by addition of NH4PF6, yields the cationic ruthenium carbene trans-[RuCl(=CHCH3)(κ2-3)2]PF6 (8), together with small quantities of the hydrido compound [RuH(κ2-3)2]PF6 (9). The Grubbs catalyst [RuCl2(=CHPh)(PCy3)2] (10) reacts with both 3 and [Fe(η5-C5H4PPh2)2] (11), also by ligand substitution, to give the corresponding chelate complexes [RuCl2(=CHPh)(κ2-3)] (12) and [RuCl2(=CHPh)(κ2-11)] (13); the latter has been characterized by X-ray crystal structure analysis.

Homoleptic tris-cyclometalated platinum(IV) complexes: a new class of long-lived, highly efficient 3LC emitters

The synthesis of meridional and facial isomers of tris-cyclometalated Pt(IV) complexes, [Pt(C^N)3]OTf, where C^N is a C-deprotonated 2-phenylpyridine-based ligand or 1-phenylpyrazole, is reported for the first time. The facial isomers exhibit high-energy emissions from essentially 3LC excited states, characterized by lifetimes of hundreds of microseconds and quantum yields up to 0.49 at room temperature in fluid solution, the highest ever found for Pt(IV) complexes. Stern–Volmer studies demonstrate the high sensitivity of the facial isomers toward oxygen and their electrochemical characterization reveals large redox gaps and a strong oxidizing character in the excited state.

Recent advances in the chemistry of gold(I) complexes with C-, N- and S-donor ligands part I: alkynyl, amino, imino and nitrido derivatives

In this paper, and in Part II to be published later, we give an account of the chemistry of gold(I) complexes with C-, N-, and S-donor ligands. In this first part, the synthesis of gold(I) complexes with alkynyl and N-donor ligands is reported.

Complexes with S-donor ligands. Part 2. Synthesis of anionic bis(thiolato)gold(I) complexes. Crystal structure of [N(PPh3)2][Au(SR)2](R = benzoxazol-2-yl)

The reaction of [N(PPh3)2][Au(acac)2](Hacac = acetylacetone) with HSR gave acetylacetone and the complexes [N(PPh3)2][Au(SR)2][HSR = benzoxazole-2(1H)-thione 1, pyrimidine-2(1H)-thione 2, pyridine-2(1H)-thione 3, 2,3,4,6-tetra-O-acetyl-1-thio-β-D-glucopyranose 4, 2-thiouracil (2,3-dihydro-2-thioxo-1H-pyrimidin-4-one)5, 2,3-dihydro-1H-benzimidazole-2-thione 6, 2-thiomailc acid 7, 2-sulfanylethanol 8, D-penicillamine (3-sulfanylvaline)9]. The crystal structure of 1 has been solved. The gold atom adopts the usual linear co-ordination [175.11(5)°] and the Au–S bond distances are normal [2.281 (2) and 2.283(2)A].

Synthesis of the first trithiocarbonatogold complex: [N(PPh3)2]2[Au2(µ2-η2-CS3)2]. First crystal structure of a µ2-η2-bridging trithiocarbonato complex

The reaction of [N(PPh3)2][Au(SH)2] with CS2 gives [N(PPh3)2]2[Au2(µ2-η2-CS3)2] whose crystal structure shows planar [Au2(µ2-η2-CS3)2]2– anions and two [N(PPh3)2] cations; the coordination at gold is almost linear [SAuS 172.80(5)°] and both gold atoms are doubly bridged by CS3 anions, associated with a very short Au ⋯ Au contact of 2.7998(4)A.

Recent advances in the chemistry of gold(I) complexes with C-, N- and S-donor ligands Part II: Sulfur ylide, hydrosulfido, sulfido, trithiocarbonato, dithiocarbimato and 1, 1-ethylenedithiolato derivatives

In these two papers we report the chemistry of gold(I) complexes with C-, N-, and S-donor ligands, as recently published by our group, and describe some previously unpublished results. In Part I, the synthesis of alkynyl, amino, imino and nitrido gold(I) complexes was reported (1). In this part, we give an account of the synthesis of gold(I) complexes with sulfur-containing ligands such as sulfur ylides, hydrosulfido, sulfido, trithiocarbonato, dithiocarbimato and 1, 1-ethylenedithiolato.

Dinuclear Copper(I) and Copper(I)/Silver(I) Complexes with Condensed Dithiolato Ligands1

The Cu(III) complex Pr 4N[Cu{S 2C=( t-Bu-fy)} 2] ( 1) ( t-Bu-fy = 2,7-di- tert-butylfluoren-9-ylidene) reacts with [Cu(PR 3) 4]ClO 4 in 1:1 molar ratio in MeCN to give the dinuclear complexes [Cu 2{[SC=( t-Bu-fy)] 2S}(PR 3) n ] [ n = 2, R = Ph ( 2a); n = 3, R = To ( 3b); To = p-tolyl]. The analogue of 2a with R = To ( 2b) can be obtained from the reaction of 3b with 1/8 equiv of S 8. Compound 2b establishes a thioketene-exchange equilibrium in solution leading to the formation of [Cu 4{S 2C=( t-Bu-fy)} 2(PTo 3) 4] ( 4b) and [Cu 2{[SC=( t-Bu-fy)] 3S}(PTo 3) 2] ( 5b). Solid mixtures of 4b and 5b in varying proportions can be obtained when the precipitation of 2b is attempted using MeCN. The reactions of 1 with AgClO 4 and PPh 3, PTo 3 or PCy 3 in 1:1:4 molar ratio in MeCN afford the heterodinuclear complexes [AgCu{[SC=( t-Bu-fy)] 2S}(PR 3) 3] [R = Ph ( 6a), To ( 6b), Cy ( 6c)]. Complex 6c dissociates PCy 3 in solution to give the bis(phosphine) derivative [AgCu{[SC=( t-Bu-fy)] 2S}(PCy 3) 2] ( 7c), which undergoes the exchange of [M(PCy 3)] (+) units in CD 2Cl 2 solution to give small amounts of [Cu 2{[SC=( t-Bu-fy)] 2S}(PCy 3) 2] ( 2c) and [Ag 2{[SC=( t-Bu-fy)] 2S}(PCy 3) 2] ( 8c). Complexes 6a and b participate in a series of successive equilibria in solution, involving the dissociation of phosphine ligands and the exchange of [M(PCy 3)] (+) units to give 2a or 3b and the corresponding disilver derivatives [Ag 2{[SC=( t-Bu-fy)] 2S}(PR 3) 2] [R = Ph ( 8a), To ( 8b)], followed by thioketene-exchange reactions to give [AgCu{[SC=( t-Bu-fy)] 3S}(PR 3) 2] [R = Ph ( 9a), To ( 9b)]. Complexes 9a and b can be directly prepared from the reactions of 1 with AgClO 4 and PPh 3 or PTo 3 in 1:1:3 molar ratio in THF. The crystal structures of 3b, 6b, 6c, 7c, and 9a have been solved by single-crystal X-ray diffraction studies and, in the cases of 7c and 9a, reveal the formation of short Ag...Cu metallophilic contacts of 2.8157(4) and 2.9606(6) A, respectively.

Influence of Ancillary Ligands and Isomerism on the Luminescence of Bis-cyclometalated Platinum(IV) Complexes

The synthesis, characterization, and photophysical properties of a wide variety of bis-cyclometalated Pt(IV) complexes featuring a C2-symmetrical or unsymmetrical {Pt(ppy)2} unit (sym or unsym complexes, respectively; ppy = C-deprotonated 2-phenylpyridine) and different ancillary ligands are reported. Complexes sym-[Pt(ppy)2X2] (X = OTf(-), OAc(-)) were obtained by chloride abstraction from sym-[Pt(ppy)2Cl2] using the corresponding AgX salts, and the triflate derivative was employed to obtain homologous complexes with X = F(-), Br(-), I(-), trifluoroacetate (TFA(-)). Complexes unsym-[Pt(ppy)2(Me)X] (X = OTf(-), F(-)) were prepared by reacting unsym-[Pt(ppy)2(Me)Cl] with AgOTf or AgF, respectively, and the triflate derivative was employed as precursor for the synthesis of the homologues with X = Br(-), I(-), or TFA(-) through its reaction with the appropriate anionic ligands. The previously reported complexes unsym-[Pt(ppy)2X2] (X = Cl(-), Br(-), OAc(-), TFA(-)) are included in the photophysical study to assess the influence of the arrangement of the cyclometalated ligands. Density functional theory (DFT) and time-dependent DFT calculations on selected derivatives were performed for a better interpretation of the observed excited-state properties. Complexes sym-[Pt(ppy)2X2] (except X = I(-)) exhibit phosphorescent emissions in fluid solutions at 298 K arising from essentially (3)LC(ppy) excited states, which are very similar in shape and energy. However, their efficiencies are heavily dependent on the nature of the ancillary ligands, which affect the energy of deactivating ligand-to-ligand charge transfer (LLCT) or ligand-to-metal charge transfer (LMCT) states. The fluoride derivative sym-[Pt(ppy)2F2] shows the highest quantum yield of this series (Φ = 0.398), mainly because the relatively high metal-to-ligand charge transfer admixture in its emitting state leads to a high radiative rate constant. Complexes unsym-[Pt(ppy)2X2] emit from (3)LC(ppy) states in frozen matrices at 77 K, but their emissions are totally quenched in fluid solution at 298 K because of the presence of low-lying, dissociative LMCT excited states, which also cause photoisomerization reactions. Complexes unsym-[Pt(ppy)2(Me)X] (X = F(-), Cl(-), Br(-), TFA(-)) show strong emissions in fluid solutions at 298 K (Φ = 0.52-0.63) because deactivating LMCT states lie at high energies. However, derivative unsym-[Pt(ppy)2(Me)I] is only weakly emissive at 298 K because of the presence of low-lying LLCT [p(I) → π*(ppy)] states.

CS2 insertion into a gold–carbon bond. First syntheses and characterization of 2,2-diacetylethylene-1,1-dithiolato complexes. Crystal structure of [N(PPh3)2][Au{η2-S2CC(COMe)2}2]†

The reaction of [N(PPh3)2][Au(acac)2] (acac = acetylacetonate) with CS2 gives [N(PPh3)2]2[Au2{µ2:η2-S2CC(COMe)2}2], which reacts with PhICl2 to give [N(PPh3)2][Au{η2-S2CC(COMe)2}2], for which the crystal structure is determined; these are the first characterized 2,2-diacetylethylene-1,1-dithiolato complexes of any element.