Luminescent heterohexanuclear complexes with platinum alkynyl and silver diphosphine as components

Reactions between the building blocks [Ag2(mu-Ph2PXPPh2)2(MeCN)2]2+ and [Pt(C[triple bond]CC6H4R-p)4]2- (R = H, CH3) afforded strongly luminescent acetylide-linked neutral heterohexanuclear complexes Pt2Ag4(mu-Ph2PNPPh2)4 (C[triple bond]CC6H4R-p)4 (R = H, 1; CH3, 2) for X = NH, but a heterotrinuclear complex cation [PtAg2(mu-PPh2CH2PPh2)2 (C[triple bond]CC6H5)2(CH3CN)2]2+ (3(2+)) for X = CH2.     

Self-assembly luminescent heteroheptanuclear complexes with metal diphosphine and metal thiolate as components

Self-assembly between the building blocks [M2(mu-dppm)2(MeCN)2]2+ (M = Cu or Ag; dppm = bis(diphenylphosphino)methane) and M'(aet)2 (aet = 2-aminoethanethiolate) afforded luminescent heterohepta-nuclear complexes [Cu4M'3(mu-dppm)3(mu 3-aet)4(mu-aet)2]4+ (M' = Ni 1; Pd 2) or heterotrinuclear complexes [Ag2M'(mu-dppm)2(mu-aet)2]2+ (M' = Ni 3, Pd 4).     

A vibrational and DFT study of M(diimine)(dithiolate) complexes and their complexation route

A complete vibrational spectra analysis of the Pd(phen)(bdt), the free ligands, where phen=1,10-phenanthroline and bdt=1,2-benzenedithiolate and the starting material of its synthesis, Pd(phen)Cl(2), is performed in this paper. The molecular geometry, binding and spectroscopic properties for the aforementioned compounds are studied in detail by FT-IR, Raman and DFT methods using B3LYP functional together with basis sets of valence triple-zeta quality. Further, changes in FT-IR and Raman spectra during complexation are monitored revealing the electron delocalization over ligands. They are also consistent with pi-back donation theory.     

Identifying of charge-transfer transitions and reactive centers in M(diimine)(dithiolate) complexes by DFT techniques

This review is focused on theoretical aspects of mixed diimine–dithiolate complexes by means of DFT and TD-DFT methods. Thus, the geometry, the character of charge-transfer transitions and excited states in a series of M(diimine)(dithiolate), where M = Ni, Pd and Pt, is examined by DFT and TD-DFT techniques combined with polarized continuum model. The theoretical calculations reveal not only the role of the ligands – namely diimine and dithiolato and their substituents – but also the role of the metal in the excited triplet and singlet states and as a consequence in the properties of these complexes (electronic and photophysics) and their potential use as photosensitizers, NLO materials, light energy conversion materials and biological agents. The calculated energies of the lowest triplet and singlet state in all these complexes are in good agreement with absorption spectra and luminescence studies—where they are available. The contribution of the metal in the chemical and photophysics properties of this class of compounds is also demonstrated by two indices derived by DFT techniques: NICS (for chemical) and Fukui functions (for chemical and photophysical properties). The former acts as a meter of the delocalization of these molecules whereas the latter identifies the reactive centres of the molecule. All the theoretical results are in accordance with the experimental ones—geometrical structures, absorption, luminescence and ¹H NMR spectra as well as products of given reactions, indicating the applicability of the DFT and TD-DFT techniques in examining the properties of metal coordinated complexes especially in a series of the same class of compounds.     

The metal is the kinetic site of protonation of (diimine)Pt dimethyl complexes

Protonolysis of (diimine)PtMe2 (1) complexes in CD2Cl2 containing CD3CN at -78 degrees C yields (diimine)PtMe2(H)(NCCD3)+ (4), (diimine)PtMe(NCCD3)+ (5), and methane. The relative yields of 5 and methane decrease with increasing concentrations of CD3CN. This is consistent with protonation of 1 occurring directly at the metal, rather than at a methyl group. The principle of microscopic reversibility then implies that the deprotonation in "Shilov-type C-H activation" occurs from a Pt(IV) hydridomethyl intermediate, rather than from a Pt sigma-methane complex.     

Sensitizing the Sensitizer: The Synthesis and Photophysical Study of Bodipy-Pt(II)(diimine)(dithiolate) Conjugates

The dyads 3, 4, and 6, combining the Bodipy chromophore with a Pt(bpy)(bdt) (bpy = 2,2'-bipyridine, bdt = 1,2-benzenedithiolate, 3 and 6) or a Pt(bpy)(mnt) (mnt = maleonitriledithiolate, 4) moiety, have been synthesized and studied by UV-vis steady-state absorption, transient absorption, and emission spectroscopies and cyclic voltammetry. Comparison of the absorption spectra and cyclic voltammograms of dyads 3, 4, and 6 and those of their model compounds 1a, 2, 5, and 7 shows that the spectroscopic and electrochemical properties of the dyads are essentially the sum of their constituent chromophores, indicating negligible interaction of the constituent chromophores in the ground state. However, emission studies on 3 and 6 show a complete absence of both Bodipy-based fluorescence and the characteristic luminescence of the Pt(bpy)(bdt) unit. Dyad 4 shows a weak Pt(mnt)-based emission. Transient absorption studies show that excitation of the dyads into the Bodipy-based (1)ππ* excited state is followed by singlet energy transfer (SEnT) to the Pt(dithiolate)-based (1)MMLL'CT (mixed metal-ligand to ligand charge transfer) excited state ([Formula: see text] = 0.6 ps, [Formula: see text] = 0.5 ps, and [Formula: see text] = 1.6 ps), which undergoes rapid intersystem crossing to the (3)MMLL'CT state due to the heavy Pt(II) ion. The (3)MMLL'CT state is then depopulated by triplet energy transfer (TEnT) to the low-lying Bodipy-based (3)ππ* excited state ([Formula: see text] = 8.2 ps, [Formula: see text] = 5 ps, and [Formula: see text] = 160 ps). The transition assignments are supported by TD-DFT calculations. Both energy-transfer processes are shown to proceed via a Dexter electron exchange mechanism. The much longer time constants for dyad 6 relative to 3 are attributed to the significantly poorer coupling and resonance of charge-separated species that are intermediates in the electron exchange process.     

Dye sensitization of nanocrystalline titanium dioxide with square planar platinum(II) diimine dithiolate complexes

A series of platinum-based sensitizers of the general type Pt(NN)(SS), where NN is 4,4'-dicarboxy-2,2'-bipyridine (dcbpy) or 4,7-dicarboxy-1,10-phenanthroline (dcphen) and SS is ethyl-2-cyano-3,3-dimercaptoacrylate (ecda), quinoxaline-2,3-dithiolate (qdt), 1,2-benzenedithiolate (bdt), or 3,4-toluenedithiolate (tdt), that have various ground-state oxidation potentials has been synthesized and anchored to nanocrystalline titanium dioxide electrodes for light-to-electricity conversion in regenerative photoelectrochemical cells with an I(-)/I(-)(3) acetonitrile electrolyte. The intense mixed-Pt/dithiolate-to-diimine charge-transfer absorption bands in this series could be tuned from 440 to 580 nm by choosing appropriate dithiolate ligands, and the highest occupied molecular orbitals varied by more than 500 mV. Spectrophotometric titration of the Pt(dcphen)(bdt) complex exhibits a ground-state pK(a) value of 3.2 +/- 0.1, which can be assigned to the protonation of the carboxylate group of the dcphen ligand. Binding of Pt(dcbpy)(qdt) to porous nanostructured TiO(2) films was analyzed using the Langmuir adsorption isotherm model, yielding an adsorption equilibrium constant of 4 x 10(5) M(-1). The amount of dye adsorbed at the surface of TiO(2) films was 9.5 x 10(-8) mol/cm(2), which is ca. 50% lower than the full monolayer coverage. The resulting complexes efficiently sensitized TiO(2) over a notably broad spectral range and showed an open-circuit potential of ca. 600 mV with an impressive fill factor of > 0.70, making them attractive candidates for solar energy conversion applications. The visible spectra of the 3,4-toluenedithiol-based sensitizers showed an enhanced red response, but the lower photocurrent efficiency observed for these sensitizers stems in part from a sluggish halide oxidation rate and a fast recombination of injected electrons with the oxidized dye.     

Coordination polymers of gold(I) with dithiolate and diphosphine ligands

The first neutral, hybrid organic-inorganic coordination polymers with linear gold(I) centres in the backbone have the formula [X(OCH2CH2O2CCH2SAu)2(mu-dppee)]n, X = 1,4-C6H4 or C10H6, dppee = trans-bis(diphenylphospino)ethylene, are easily formed by self-assembly during crystallization from macrocyclic isomers (n = 1), and form sheet structures anchored by secondary Au...S and S...S interactions in the solid state.     

Syntheses, characterization, and luminescence of Pt II-M I (M = Cu, Ag, Au) heterometallic complexes by incorporating Pt(diimine)(dithiolate) with [M2(dppm)2]2+ (dppm = Bis(diphenylphosphino)methane)

Reaction of Pt(diimine)(edt) (edt = 1,2-ethanedithiolate) with M(2)(dppm)(2)(MeCN)(2)(2+) (dppm = bis(diphenylphosphino)methane) gave heterotrinuclear complexes [PtCu(2)(edt)(mu-SH)(dppm)(3)](ClO(4)) (11) and [PtCu(2)(diimine)(2)(edt)(dppm)(2)](ClO(4))(2) (diimine = 2,2'-bpyridine (bpy), 12; 4,4'-dibutyl-2,2'-bipyridine (dbbpy), 13; phenanthroline (phen), 14; 5-bromophenanthroline (brphen), 15) when M = Cu(I). The reaction, however, afforded tetra- and trinuclear complexes [Pt(2)Ag(2)(edt)(2)(dppm)(2)](SbF(6))(2) (17) and [PtAu(2)(edt)(dppm)(2)](SbF(6))(2) (21) when M = Ag(I) and Au(I), respectively. The complexes were characterized by elemental analyses, electrospray mass spectroscopy, (1)H and (31)P NMR, IR, and UV-vis spectrometry, and X-ray crystallography for 14, 17, and 18. The Pt(II)Cu(I)(2) heterotrinuclear complexes 11-15 exhibit photoluminescence in the solid states at 298 K and in the frozen acetonitrile glasses at 77 K. It is likely that the emission originates from a ligand-to-metal charge transfer (dithiolate-to-Pt) (3)[p(S) --> d(Pt)] transition for 11 and from an admixture of (3)[d(Cu)/p(S)-pi(diimine)] transitions for 12-16. The Pt(II)(2)Ag(I)(2) heterotetranuclear complexes 17 and 18 are nonemissive in the solid states and in solutions at 298 K but show photoluminescence at 77 K. The Pt(II)Au(I)(2) heterotrinuclear complexes 19-21, however, are luminescent at room temperature in the solid state and in solution. Compounds 19 and 20 afford negative solvatochromism associated with a charge transfer from an orbital of a mixed metal/dithiolate character to a diimine pi orbital.     

New heterotrinuclear complexes containing copper(II) and a group IV metal

Summary Heterotrinuclear complexes of the type [Cu₂(TETA)₂Cl₄M] (M = Si, Ge, Sn, Ti and Zr; TETA = triethylene tetramine) have been prepared by direct reaction of [Cu[TETA)]Cl₂ with MCl₄ in a 21 ratio in MeOH. The compounds have been characterized by elemental analyses, e.s.r., electronic and i.r. spectra, magnetic susceptibility and conductivity measurements. The results indicate that [Cu(TETA)]Cl₂ is square planar and ionic, while its heterotrinuclear complexes, [Cu₂(TETA)₂Cl₄M], are covalent with an octahedral environment around the copper(II) ion.     

Studies of structural effects on the half-wave potentials of mononuclear and dinuclear nickel(II) diphosphine/dithiolate complexes

Two series of mononuclear Ni(II) complexes of the formula (PNP)Ni(dithiolate) where PNP = R2PCH2N(CH3)CH2PR2, R = Et and Ph, have been synthesized containing dithiolate ligands that vary from five- to seven-membered chelate rings. Two series of dinuclear Ni(II) complexes of the formula {[(diphosphine)Ni]2(dithiolate)}(X)2 (X = BF4 or PF6) have been synthesized in which the chelate ring size of the dithiolate and diphosphine ligands have been systematically varied. The structures of the alkylated mononuclear complex, [(PNPEt)Ni(SC2H4SMe)]OTf, and the dinuclear complex, [(dppeNi)2(SC3H6S)](BF4)2, have been determined by X-ray diffraction studies. The complexes have been studied by cyclic voltammetry to determine how the half-wave potentials of the Ni(II/I) couples vary with chelate ring size of the ligands. For the mononuclear complexes, this potential becomes more positive as the natural bite angle of the dithiolate ligand increases. However, the potentials of the Ni(II/I) couples of the dinuclear complexes do not show a dependence on the chelate ring size of the ligands. Other aspects of the reduction chemistry of these complexes have been explored.     

Synthesis, structure, and properties of [Pt(II)(diimine)(dithiolate)] dyes with 3,3'-, 4,4'-, and 5,5'-disubstituted bipyridyl: applications in dye-sensitized solar cells

A family of [Pt(II)(diimine)(dithiolate)] complexes of general formula [Pt{X,X'(CO(2)R)(2)-2,2'-bipyridyl}(maleonitriledithiolate)] (where X = 3, 4, or 5 and R = H or Et) have been synthesized, spectroscopically and electrochemically characterized, and attached to a TiO(2) substrate to be tested as solar cell sensitizers. A single-crystal X-ray structure showing a large torsion angle between the bipyridyl rings was determined for [Pt{3,3'(CO(2)Et)(2)-2,2'-bipyridyl}(maleonitriledithiolate)].MeCN. The effect of changing the position of the bipyridyl substituents from 3,3' to 4,4' and 5,5' is discussed with reference to structural and electronic changes seen within the different members of the family of molecules. The first UV/vis/NIR spectroelectrochemical study of complexes of this general formula is discussed. All three complexes (where R = H) were tested as solar cell sensitizers, with the 3,3'-disubstituted bipyridyl complex giving an intermediate dye loading value but superior photovoltaic performance to those of the other two. The performance of this sensitizer is then compared with that of a well-known Ru polypyridyl sensitizer, the ditetrabutylammonium salt of [RuL(2)(NCS)(2)] (L = 2,2'-bipyridyl-4,4'-dicarboxylato), commonly called N719.     

Macrocyclic Pd(II) dithiolate complexes as catalysts in Heck reactions

The supramolecular palladium dithiolate complexes, [Pd₂(dppe)₂{S(C₆H₄)_nS}]₂(OTf)₄ and [Pd₂(dppe)₂(SCH₂C₆H₄CH₂S)]₄(OTf)₈ (dppe = 1,2-bis(diphenylphosphino)ethane) has been investigated as highly stable and robust catalysts in Heck C-C coupling reactions. The arylation of butyl acrylate and styrene with various aryl bromides under optimized catalytic systems, showed excellent yield and turnover number (410,000) of the products. The tetranuclear complexes showed slightly higher catalytic activity than the octanuclear complex.     

Luminescent Pt(II)(bipyridyl)(diacetylide) chromophores with pendant binding sites as energy donors for sensitised near-infrared emission from lanthanides: structures and photophysics of Pt(II)/Ln(III) assemblies

The complexes [Pt(bipy){CC-(4-pyridyl)}(2)] (1) and [Pt(tBu(2)bipy){CC-(4-pyridyl)}(2)] (2) and [Pt(tBu(2)-bipy)(CC-phen)(2)] (3) all contain a Pt(bipy)(diacetylide) core with pendant 4-pyridyl (1 and 2) or phenanthroline (3) units which can be coordinated to {Ln(diketonate)(3)} fragments (Ln = a lanthanide) to make covalently-linked Pt(II)/Ln(III) polynuclear assemblies in which the Pt(II) chromophore, absorbing in the visible region, can be used to sensitise near-infrared luminescence from the Ln(III) centres. For 1 and 2 one-dimensional coordination polymers [1Ln(tta)(3)](infinity) and [2Ln(hfac)(3)](infinity) are formed, whereas 3 forms trinuclear adducts [3{Ln(hfac)(3)}(2)] (tta=anion of thenoyl-trifluoroacetone; hfac=anion of hexafluoroacetylacetone). Complexes 1-3 show typical Pt(II)-based (3)MLCT luminescence in solution at approximately 510 nm, but in the coordination polymers [1Ln(tta)(3)](infinity) and [2Ln(hfac)(3)](infinity) the presence of stacked pairs of Pt(II) units with short PtPt distances means that the chromophores have (3)MMLCT character and emit at lower energy ( approximately 630 nm). Photophysical studies in solution and in the solid state show that the (3)MMLCT luminescence in [1Ln(tta)(3)](infinity) and [2Ln(hfac)(3)](infinity) in the solid state, and the (3)MLCT emission of [3{Ln(hfac)(3)}(2)] in solution and the solid state, is quenched by Pt-->Ln energy transfer when the lanthanide has low-energy f-f excited states which can act as energy acceptors (Ln=Yb, Nd, Er, Pr). This results in sensitised near-infrared luminescence from the Ln(III) units. The extent of quenching of the Pt(II)-based emission, and the Pt-->Ln energy-transfer rates, can vary over a wide range according to how effective each Ln(III) ion is at acting as an energy acceptor, with Yb(III) usually providing the least quenching (slowest Pt-->Ln energy transfer) and either Nd(III) or Er(III) providing the most (fastest Pt-->Ln energy transfer) according to which one has the best overlap of its f-f absorption manifold with the Pt(II)-based luminescence.     

D(+)-pi-A(-) charge-transfer molecules based on tricyanoquinodimethane and diphosphine metal complexes

A new family of D (+)-pi-A (-) chromophores in which the donor group is an organometallic complex and the acceptor group a tricyanoquinodimethane moiety has been synthesized by the reaction of diphosphinomethanide transition-metal complexes and 7,7',8,8'-tetracyanoquinodimethane.     

Rm.M（dmit）2型有机金属配合物的合成与表征

合成了２个系列９种新的季铵．二（在，３－一硫杂环戊烯－２－硫酮－４，５－二巯基）金属（缩写为Ｒｍ．Ｍ（ｄｍｉｔ）２）型有机金属配合物，用元素分析，ＩＣＰ和＾１ＨＮＭＲ等对它们的结构进行了表征，并讨论了光谱特征。     

Trichlorostannato(diphosphine)rhodium(I) complexes. Crystal structure of [Rh(SnCl3)(1,5-cyclooctadiene)(dppp)]

The molecular structure of [Rh(SnCl₃)(1,5-cyclooctadiene)(dppp)] [dppp = 1,3-bis(diphenylphosphino)propane] has been determined to R_F = 3.6% single-crystal X-ray techniques. The crystal contains two discrete molecules 1 and 2 per asymmetric unit. Molecule 1 is best described as distorted trigonal bipyramidal with the diolefin and the diphosphine occupying both apical and equatorial positions and the SnCl₃ group on an equatorial position, and molecule 2 as distorted square pyramidal with the equatorial positions occupied by the diolefin and the diphosphine, respectively, and the SnCl₃ fragment in the apical position. In solution at room temperature, complexes [Rh(SnCl₃)(COD)(diphosphine)] exhibit tin dissociation and various intramolecular rearrangements.     

Anionic and neutral bis(diimine)lanthanide complexes

Oxidation of ytterbium(II) complex (dpp-BIAN)Yb(DME)₂ (1) with dpp-BIAN affords an ionic compound [(dpp-BIAN)₂Yb]^?[(dpp-BIAN)Yb(DME)₂]⁺ (2) (dpp-BIAN = 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene), in which the oxidation states of the metals in anionic and cationic counterparts are different. Structurally related lanthanum(III) complex [(dpp-BIAN)₂La]^?[(dpp-BIAN)La(DME)₂]⁺ (3) has been prepared reacting excess of metallic lanthanum with dpp-BIAN. Compound [(dpp-BIAN)₂La]^?[K(Et₂O)₄]⁺ (4) has been isolated from the reaction of LaI₃ with three molar equivalents of potassium and one molar equivalent of dpp-BIAN in diethyl ether. The reaction of SmI₂ with dpp-BIAN and potassium affords complex [(dpp-BIAN)₂Sm]^?[K(C₆H₆)]⁺ (5). Treatment of compound 5 with 0.5 molar equivalent of iodine produces neutral complex (dpp-BIAN)₂Sm (6). Molecular structures of complexes 2–6 have been determined by X-ray crystallography.     

A remarkable temperature-dependent,accidental degeneracy of 31P NMR chemical shifts in Ru(II) diphosphine/diimine complexes

Several cis-RuX2((R)-BINAP)(diimine) complexes have been prepared, and many of these exhibit an unusual temperature-dependent, accidental degeneracy of the 31P shifts in their solution NMR spectra.     

EPR of copper(II) chloride complexes with diphosphine dioxides

Stepwise formation of copper(ll) chloride complexes with diphosphine dioxides has been studied using paramagnetic resonance. It was found that in complexes with a copper:ligand composition of 11 substituents have little effect on parameters of the anisotropic EPR spectra. The spectra of complexes with a metal:ligand composition of 12 are considerably more sensitive to the introduction of substituents; this is explained by sterically dependent differences in the structure of the complexes. The possibility of trisligand complexes being formed is evidently largely determined by the size of the groups on the phosphorus atoms.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 362–368, February, 1991.