Synthesis and characterization of diiron ethanedithiolate complexes with monosubstituted phosphine ligands

Reactions of (μ-edt)Fe₂(CO)₆ (edt = SCH₂CH₂S) (1) with the monophosphine ligands Ph₂PCH₂Ph, Ph₂PC₆H₁₁, Ph₂PCH₂CH₂CH₃, or P(2-C₄H₃O)₃ in the presence of Me₃NO?2H₂O afforded (μ-edt)Fe₂(CO)₅L [L = Ph₂PCH₂Ph, 2; Ph₂PC₆H₁₁, 3; Ph₂PCH₂CH₂CH₃, 4; P(2-C₄H₃O)₃, 5] in 70–88% yields. Complexes 2–5 were characterized by spectroscopy and single crystal X-ray diffraction analysis. The phosphorus of 2–5 is in an apical position of the distorted octahedral geometry of iron.     

Synthesis,structures, and electrochemistry of diiron toluene-3,4-dithiolate complexes containing phosphine ligands

Transition Metal Chemistry - In this paper, four diiron toluene-3,4-dithiolate complexes with phosphine ligands were synthesized and characterized. Treatment of complex...     

Structural studies of diiron complexes with monophosphine ligands tris(4-chlorophenyl)phosphine or diphenyl-2-pyridylphosphine

Four diiron dithiolate complexes with monophosphine ligands have been prepared and structurally characterized. Reactions of (μ-SCH₂CH₂S-μ)Fe₂(CO)₆ or [μ-SCH(CH₃)CH(CH₃)S-μ]Fe₂(CO)₆ with tris(4-chlorophenyl)phosphine or diphenyl-2-pyridylphosphine in the presence of Me₃NO·2H₂O afforded diiron pentacarbonyl complexes with monophosphine ligands (μ-SCH₂CH₂S-μ)Fe₂(CO)₅[P(4-C₆H₄Cl)₃] (1), (μ-SCH₂CH₂S-μ)Fe₂(CO)₅[Ph₂P(2-C₅H₄N)] (2), [μ-SCH(CH₃)CH(CH₃)S-μ]Fe₂(CO)₅[P(4-C₆H₄Cl)₃] (3), and [μ-SCH(CH₃)CH(CH₃)S-μ]Fe₂(CO)₅[Ph₂P(2-C₅H₄N)] (4) in good yields. Complexes 1–4 were characterized by elemental analysis, ¹H NMR, ³¹P{¹H} NMR and ¹³C{¹H} NMR spectroscopy. Furthermore, the molecular structures of 1–4 were confirmed by X-ray crystallography.     

Synthesis,structure and thermal rearrangement of tetramethyldisilane-bridged bis(cyclopentadienyl) diiron complexes with a phosphite or phosphine ligand substitution

Photolysis of tetramethyldisilane-bridged bis(cyclopentadienyl) tetracarbonyl di-iron in the presence of phosphite or phosphine ligand afforded the corresponding Fe–Fe bond complexes with one carbonyl replaced by a phosphite or phosphine ligand: [(Me₂SiSiMe₂)Cp₂Fe₂(CO)(PR₃)(μ-CO)₂] (R=OPh, 1; OEt, 2; Ph, 3). When these complexes were heated in refluxing xylene, they become rearranged to the corresponding products [(Me₂SiCpFe)₂(CO)₃(PR₃)] (R=OPh, 4; OEt, 5; Ph, 6). It was found that, after phosphite or phosphine ligand substitution, the rearrangement became facile. The molecular structures of 1–6 were characterized by IR, ¹H NMR spectra and elemental analyses. The crystal structures of 1 and 4 were determined by X-ray diffraction analysis.     

Synthesis and electrochemistry of phenyl-functionalized diiron propanedithiolate complexes with bidentate phosphine ligands

Carbonyl substitution reactions of [μ-(SCH₂)₂CHC₆H₅]Fe₂(CO)₆ with bidentate phosphine ligands, cis-1,2-bis(diphenylphosphine)ethylene (cis-dppv) and N,N-bis(diphenylphosphine)propylamine [(Ph₂P)₂N-Pr-n], yielded an asymmetrically substituted chelated complex [(μ-SCH₂)₂CHC₆H₅]Fe₂(CO)₄(k ²-dppv) and a symmetrically substituted bridging complex [(μ-SCH₂)₂CHC₆H₅]Fe₂(CO)₄[μ-(PPh₂)₂N-Pr-n] under different reaction conditions. Both complexes were fully characterized by spectroscopic methods and by X-ray crystallography. Their electrochemical behaviors were observed by cyclic voltammetry, and the catalytic electrochemical reduction of protons from acetic or trifluoroacetic acid to give dihydrogen mediated by complex [(μ-SCH₂)₂CHC₆H₅]Fe₂(CO)₄(k ²-dppv) was investigated.     

Gold(I) complexes with tertiary phosphine sulfide ligands

Phosphine sulfides and their gold(I) complexes with general formula R₃P=S—Au—X (X = Cl^–, Br^– or CN^–) were prepared and characterized by elemental analyses, i.r. and ³¹P-n.m.r. spectroscopy. A decrease in the i.r. frequency of the P=S bond in the ligands upon complexation, is indicative of S coordination to gold (I). The ³¹P-n.m.r. spectra revealed that electronegativity of the substituents and angles between them were the two most important factors influencing the ³¹P-n.m.r. chemical shifts. The phosphorus resonance was observed to be more downfield in alkyl substituted phosphine sulfides as compared to the aryl substituted phosphine sulfides. Ligand scrambling in the Cy₃P=S—Au—CN complex in solution, to form [(Cy₃P=S)₂Au]⁺ and [Au(CN)₂]^–, was investigated by ¹³C and ¹⁵N-n.m.r. spectroscopy. Equilibrium constants (K _eq) for scrambling of the Cy₃P=S—Au—CN complex and for its analogue, Cy₃P=Se—Au—CN were measured by integrating the ¹³C-n.m.r. at 297 K and were found to be 0.147 and 1.81 respectively.     

Synthesis,characterisation and crystal structures of three trinuclear cadmium(II) complexes with multidentate Schiff base ligands

Three novel Schiff base Cd(II) trimeric complexes, [Cd₃(L¹)₂(SCN)₂(CF₃COO)₂] (1), [Cd₃(L¹)₂(SCN)₂(HCONMe₂)] (2) and [Cd₃(L²)₂{N(CN)₂}₂] (3) have been prepared from two different symmetrical Schiff bases H₂L¹ and H₂L² (where H₂L¹ = N¹,N³-bis(salicylideneimino)diethylenetriamine, a potentially pentadentate Schiff base with a N₃O₂ donor set, and H₂L² = N¹,N³-bis(3-methoxysalicylideneimino)diethylenetriamine, a potentially heptadentate Schiff base with a N₃O₄ donor set). All the complexes have been synthesised under similar synthetic procedures and their crystal structures have been established by single crystal X-ray diffraction methods. The ligands and their metal complexes have been characterised by analytical and spectroscopic techniques. Among the three complexes, 1 and 3 are linear whereas 2 is a cyclic trimer. In 1 and 3, all the doubly phenoxo bridged Cd(II) metal centres are in a distorted octahedral environment. In complex 2, two of the three Cd(II) centres reside in a distorted octahedral environment and the remaining one enjoys a monocapped octahedral geometry. Altogether the variety in the bridging mode of two new salen-type ligands has been established through these complexes.     

Synthesis and X-ray crystal structures of three copper(II) complexes of 1,4- bis (di-2-pyridylmethyl)phthalazine

The synthesis and X-ray crystal structures of three discrete copper(II) complexes of 1,4-bis(di-2-pyridylmethyl)phthalazine (L) are reported. The complexes 1–3 have Cu₂L, Cu₃L and Cu₂L₂ composition and display interesting relationships to previously reported complexes of this ligand.     

Palladium(0) complexes coordinated with substituted olefins and tertiary phosphine ligands

New palladium(0) complexes with a variety of coordinated olefins [Pd(olefin)(PMePh₂)₂] (II) (olefin = styrene, ethyl methacrylate, methyl methacrylate, methyl acrylate, methacrylonitrile, and dimethyl maleate), were prepared by the reactions of [PdEt₂(PMePh₂)₂] (I) with corresponding olefins in toluene. These complexes were characterized by means of elemental analysis, IR and ¹H NMR spectroscopy and the chemical reactions. The dissociation of the coordinated olefin from complex II in solution was confirmed by spectroscopic studies of [Pd(mma)(PMePh₂)₂] (mma = methyl methacrylate). From the variable temperature NMR study, kinetic parameters for the dissociation process were determined as E_a = 7 kcal/mol, and ΔS³ (293 K) = -30 cal/deg · mol. Some new hydrido complexes, [Pd(H)ClL₂] (IV) (L = PMePh₂, PEtPh₂ and PEt₂Ph), were prepared by the reactions of [Pd(olefin)L₂] with dry HCl.     

Platinum (II) phosphine complexes with acetylene ligands containing 1,4,5,8-naphthalenediimide: Synthesis, crystal structure and electrochemistry

A new acetylene ligand modified with the electron-accepting 1,4,5,8-naphthalenediimide group and its Pt(II) phosphine complexes are reported. The Pt(II) complexes incorporate optical properties of the imide group, and display two reversible imide-centred reduction processes.     

Synthesis,reactivity and x-ray crystal structures of mixed thiazolato- or carboxylato- carbonyl(phosphine) rhenium(I) complexes

Summary The compound [Re(CO)₃(PPh₃)₂Cl] reacts with the lithium salt of thiazole derivatives (L¹H = 2-amino-benzothiazole, L²H = 2–N-methyl-aminothiazole, L³H = 2–N-phenylaminothiazole, L⁴H = 2–N-(4-methoxyphenyl)aminothiazole, L⁵H = 2–N(4-nitrophenyl)aminothiazole) to give [Re(CO)₂-(PPh₃)₂(L)]. The compounds have been characterized by elemental analysis, i.r. and¹H n.m.r. spectra. At room temperature [Re(CO)₂(PPh₃)(L²)] reacts with L⁶H (L⁶H = diphenylacetic acid), to give the carboxylato complex [Re(CO)₂ .The crystal structures of [Re(CO)₂(PPh₃)₂(L²)] (2) and [Re(CO)₂(PPh₃)₂(L⁶)] (6) were determined by x-ray crystallography. [Re(CO)₂(PPh₃)₂(L²)] crystallizes in the monoclinic space group P2₁/m witha = 9.16(1),b= 24.82(2),c =9.12(1) Å, and = 115.81(4)°; D_c = 1.56 g cm^–3for Z = 2.The structure was refined to a final R of 6.4%. The molecules have C_s symmetry. The rhenium atom is six-coordinate with approximately octahedral geometry. The anionic ligand is chelating through the nitrogen atoms and is strictly planar allowing delocalization of the -electron density. [Re(CO)₂(PPh₃)₂(L⁶)] (6) crystallizes in the monoclinic space group P2₁/n witha = 22.203(5),b = 18.651(5),c =10.653(3) Å, = 91.08(3)°, Dc = 1.47 g cm^–3 for Z = 4. The structure was refined to a final R of 4.7%. The complex is monomeric and the rhenium atom is distorted octahedral with two mutuallytrans PPh₃ ligands, twocis CO ligands and one chelating Ph₂CHCO ₂ ^– ion.     

Synthesis,crystal structures and electrocatalytic properties of bridgehead-C-functionalized diiron dithiolate complexes

To investigate the influence of bridgehead-C functionality in diiron dithiolate complexes on the molecular structure and electrocatalytic properties of [FeFe]-hydrogenase models, three new bridgehead-C-functionalized model complexes 1–3 have been synthesized and structurally characterized. Treatments of parent complex [(μ-SCH₂)₂CHCO₂H][Fe₂(CO)₆] (A) with the esterification agents o-MeC₆H₄OH, p-ClC₆H₄OH, or p-HOC₆H₄CHO in the presence of 4-dimethylaminopyridine and dicyclohexylcarbodiimide in CH₂Cl₂ at room temperature resulted in formation of [(μ-SCH₂)₂CHCO₂R][Fe₂(CO)₆] (R = o-MeC₆H₄–, 1; p-ClC₆H₄–, 2; p-OHCC₆H₄–, 3) in 53–55% yields. The new complexes 1–3 were characterized by elemental analysis, IR and NMR spectroscopy, and especially determined by X-ray crystallography. The electrochemical properties of 1–3 and the electrocatalytic H₂ evolution catalyzed by 1 have been investigated by cyclic voltammetry, where 1 is a catalyst for HOAc proton reduction to H₂ under electrochemical conditions.     

2-(Diphenylphosphino)benzoate-functionalized diiron ethane-1,2-dithiolate complexes with uncoordinated or coordinated phosphine ligand

Abstract

Treatment of the starting complex [Fe₂(CO)₆{μ-SCH₂CH(CH₂OH)S}] (1) with 2-(diphenylphosphino)benzoic acid in the presence of N,N’-dicyclohexylcarbodiimide and 4-dimethylaminopyridine gave the corresponding ester derivative [Fe₂(CO)₆{μ-SCH₂CH(CH₂O₂CC₆H₄PPh₂-2)S}] (2) in 92% yield. Further treatment of complex 2 with one equivalent of Me₃NO · 2?H₂O as the decarbonylating agent yielded diphenylphosphino-substituted complex [Fe₂(CO)₅{μ-SCH₂CH(CH₂O₂CC₆H₄PPh₂-2)S}] (3) in 79% yield. Both complexes were characterized by elemental analysis, spectroscopy, as well as by X-ray crystallography. Additionally, the electrochemical properties of these complexes were studied by cyclic voltammetry.     

Synthesis,spectroscopic characterization and X-ray single crystal structures of trans-bis[4-methoxyphenyl (3-methylbutyl) dithiophosphinato] nickel(II) and bis [4-methoxyphenyl (3-methylbutyl) dithiophosphinato]cobalt(II) complexes

Thionation of 3-methylbutylmagnesium bromide with Lawesson’s Reagent (LR) gave 4-methoxyphenyl (3-methylbutyl)dithiophosphinic acid (DTPA), and the latter was converted to the ammonium salt (NH₄L = Ammonium 4-methoxyphenyl (3-methylbutyl) dithiophosphinate). The complex, trans–bis[4-methoxyphenyl(3–methylbutyl) dithiophosphinato] nickel(II) [NiL₂], was prepared by the reaction of NH₄L with NiCl₂.6H₂O in EtOH. Bis [4-methoxyphenyl (3-methylbutyl) dithiophosphinato]cobalt(II) [(CoL₂)₂] was also prepared in the same way. The structures of the complexes have been characterized by elemental analysis, FTIR, ¹H, ¹³C, ³¹P NMR and X-ray diffraction. The single crystal X-ray structures of [NiL₂] and [(CoL₂)₂] show that the nickel complex is square planar while the cobalt counterpart has tetrahedral coordination with a dimeric structure. Bond lengths, angles, torsion angles and dihedral angles are correlated to the structures and also compared with the literature data on similar compounds.     

Synthesis,characterizations and crystal structures of new antimony (III) complexes with dithiocarbamate ligands

Eight new antimony (III) complexes containing dithiocarbamate ligands (R₂NCS₂)₂SbBr [R₂NCS₂ = OC₄H₈NCS₂ (1), C₂H₅NC₄H₈NCS₂ (2), Me₂NCS₂ (3), C₄H₈NCS₂ (4)] and (R₂NCS₂)₃Sb[R₂NCS₂ = C₅H₁₀NCS₂ (5), Bz₂NCS₂ (6), Et₂NCS₂ (7), (HOCH₂CH₂)₂NCS₂ (8)] have been synthesized by the reactions of antimony (III) halides with dithiocarbamate ligands in 1:2 or 1:3 stoichiometries. All the complexes have been characterized by elemental analysis, melting point as well as spectral [IR and NMR (¹H and ¹³C)] studies. The crystal structures of complexes 1, 5 and 8 have been determined by X-ray single crystal diffraction, and their electrochemical character has also been studied.     

Synthesis,crystal structures,luminescence and catalytic properties of three silver(I) coordination polymers with bis(imidazole) and benzenedicarboxylic acid ligands

Three new silver coordination compounds with empirical formula [Ag₂(L1)₂·(ntp)·(H₂O)_3.25]_n (1), [Ag_1.5(L1)_1.5·(H_0.5bdc)·(H₂O)₄]_n (2) and [Ag(L2)(Hmip)]_n (3) (L1 = 1,4-bis(imidazol-1-ylmethyl)benzene, L2 = 1,1′-(1,4-butanediyl)bis-1H-benzimidazole, H₂ntp = 2-nitroterephthalic acid, H₂bdc = 1,3-benzenedicarboxylic acid, H₂mip = 5-methylisophthalic acid) were synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction and physico-chemical spectroscopic methods. The silver centers display different environments with a linear geometry in 1 and 2 and distorted T-shaped geometry in 3. In 1–3, the bidentate N-donor ligands (L1 and L2) bridge neighboring silver centers to form 1D infinite chain structures. Complexes 2 and 3 are extended into 2D layers, and 1 is packed into a 3D 3,4,4,6-connected supermolecular network via classical O–H···O hydrogen bonds, while 3 is further extended into 3D framework through π–π interactions. The luminescence properties of complexes 1, 2 and 3 were investigated in the solid state. These coordination polymers possess a remarkable activity for degradation of methyl orange by persulfate in a Fenton-like process.     

Tricarbonylrhenium(I) and -technetium(I) complexes with bis(2-pyridyl)phenylphosphine and tris(2-pyridyl)phosphine

(NEt₄)₂[Re(CO)₃Br₃] or (NEt₄)₂[Tc(CO)₃Cl₃] react with bis(2-pyridyl)phenylphosphine (PPhpy₂) or tris(2-pyridyl)phosphine (Ppy₃) under formation of neutral tricarbonyl complexes of the composition [M(CO)₃X(L)] (M = Re, X = Br; M = Tc, X = Cl; L = PPhpy₂ or Ppy₃). In all isolated products, the ligands coordinate solely via two of their nitrogen atoms. All attempts to force a tripodal coordination of the phosphinopyridines failed. Removal of the bromo ligands from (NEt₄)₂[Re(CO)₃Br₃] by the addition of AgNO₃ in THF/water, and subsequent reaction of the resulting [Re(CO)₃(THF)₃](NO₃)with Ppy₃ yielded the complex [Re(CO)₃(NO₃)(Ppy₃-N,N′)] with a monodentate coordinated nitrato ligand. The products have been characterized spectroscopically and by X-ray structure analyses.     

Synthesis and structures of gold(I) phosphine complexes containing monoanionic selenocarbamate ester ligands

A series of mono- and dinuclear gold(I) phosphine complexes of the type [Au{SeC(OMe)NPh}(P)] [P = PPh₃, PTA, P(o-tolyl)₃, P(p-MeOC₆H₄)₃] and [Au₂{SeC(OMe)NPh}₂(μ-PP)] (PP = dppm, dppe, dppp, dppf, dppee) were prepared from the reaction of the appropriate chlorogold(I) phosphine complexes with N-phenyl-O-methylselenocarbamide in the presence of base. These new complexes were fully characterised by spectroscopic techniques and, in several cases, by X-ray crystallography. The differences in the solid-state structures of these selenium complexes were compared with those of some sulfur analogues.     

Silver(I) complexes with (1-pyrazolyl)pyridazine ligands: Synthesis,crystal structures and luminescent properties

Four Ag(I) coordination complexes formulated as {[Ag(L¹)(ClO₄)]}_n (1), {[Ag(L¹)(NO₃)]}_n (2), {[Ag(L¹)(PF₆)]}₂ (3) and {[Ag(L²)](ClO₄)·CH₃OH}_n (4), (L¹ = 3,6-bis(1-pyrazolyl)pyridazine, L² = 3,6-bis(3,5-dimethyl-1-pyrazolyl)pyridazine) have been synthesized in the presence of different anions [ClO₄^? (1) and (4), NO₃^? (2), PF₆^? (3)] and structurally characterized by FT-IR spectra, elemental analysis and X-ray diffraction. Studies of X-ray diffraction reveal that complexes 1, 2 and 4 show infinite helical chains, which are the alternate left- and right-handed helical chains. Furthermore, helical chains are arranged to 2D sheet via C–H?O (from anion O atoms) hydrogen bonds. As the anion changed to PF₆^?, a dinuclear molecule is formed in complex 3, further constructing a 2D sheets by C–H?F hydrogen bonds. The photoluminescence properties of all the complexes 1–4 have been investigated in the solid state at room temperature.     

Synthesis,crystal structures and catalytic epoxidation properties of dioxomolybdenum(VI) complexes with hydrazone ligands

A series of dioxomolybdenum(VI) complexes with similar hydrazone ligands have been prepared, specifically [MoO₂L¹(MeOH)] (1), [MoO₂L²(MeOH)] (2) and [MoO₂L³(MeOH)] (3), where L¹, L² and L³ are the dianionic forms of 2-chloro-N′-(2-hydroxybenzylidene)benzohydrazide, 2-chloro-N′-(2-hydroxy-5-methylbenzylidene)benzohydrazide and N′-(3-bromo-5-chloro-2-hydroxybenzylidene)-2-chlorobenzohydrazide, respectively. The complexes were characterized by physicochemical and spectroscopic methods and also by single-crystal X-ray determination. The hydrazone ligands coordinate to the Mo atoms through their phenolate O, imine N and enolic O atoms. The Mo atoms are six-coordinated in octahedral geometries. The complexes show high catalytic activities and selectivities in the epoxidation of cyclohexene with tert-butylhydroperoxide as primary oxidant.