Solution-phase disproportionation equilibria for monosubstituted Pentakis- (arylisocyanide)cobalt(I) complexes by proton-NMR studies

Equilibrium constants, K_dis, for the solvent- dependent, solution-phase disproportionation equilibria of monosubstituted pentakis(arlisocyanide)cobalt(I) complexes: 2[Co(CNR)₄L]⁺?[Co(CNR)₃L₂]⁺ + [Co(CNR)₅]⁺, K_dis = $\text{[Co(CNR)}{}_3\text{L}{}_2\text{][Co(CNR)}{}_5\text{]}\text{[Co(CNR)}{}_4\text{L]}{}^2$ are measured by planimeter-integration of proton- NMR spectra at ambient temperature. The complexes, [Co(CNR)₄L]ClO₄, R = 2,6-Me₂C₆H₃, L = P(C₆H₅)₃, P(C₆H₄Cl-p)₃, P(OC₆H₅)₃, P(OC₆H₄Cl-p)₃; R = o-MeC₆H₄, L = P(C₆H₄Cl-p)₃, P(OC₆H₅)₃, P(OC₆H₄Cl-p)₃; R = 2,4,6-Me₃C₆H₂, L = P(C₆H₅)₃; R = 2,6-Et₂C₆H₃, L = P(C₆H₅)₃; are investigated in the deuterated solvents, CDCl₃, CD₃CN, (CD₃)₂CO, C₅D₅N, CD₃NO₂, and (CD₃)₂SO. Disproportionation seems to occur in all [Co(CNR)₄L]⁺, but NMR study is facilitated by utilizing equivalent alkyl protons (i.e., Me-groups) on the RNC ligands.Correlation of K_dis values with steric-hindrance of the RNC in sets of complexes with the same P-ligand is evident in all solvents: K_dis decreases with increased steric-hindrance in RNC. The K_dis values for complexes with the same RNC and analogous triarylphosphine, triarylphosphite ligands (i.e., PR₃, P(OR)₃, same R) are approximately equal. The K_dis values for complexes of P-ligands with Cl-substituent are significantly larger than K_dis values for complexes with the corresponding unsubstituted P-ligands (e.g., [Co(CNR)₄P(C₆H₄Clp)₃]ClO₄vs. [Co(CNR)₄P(C₆H₅)₃]ClO₄) in (CD₃)₂CO and C₅D₅N solution, but are smaller in CDCl₃ and CD₃CN, and approximately equal in CD₃NO₂ and (CD₃)₂SO. Properties of the solvents are also considered.     

Silver(I)-organophosphane complexes of the dihydridobis(3-nitro-1,2,4-triazolyl)borate ligand. X-ray crystal structure of {[H2B(tz)2]Ag[P(m-tolyl)3]2} with the scorpionate ligand co-ordinated in an unidentate κ-N fashion

New silver(I) complexes have been synthesised from the reaction of AgNO₃, monodentate PR₃ (PR₃ = P(o-tolyl)₃, P(m-tolyl)₃, P(p-tolyl)₃, P(p-C₆H₄F), SeP(C₆H₅)₃) or bidentate tertiary (dppe = bis(diphenylphosphane)ethane, dppf = 1,1′-bis(diphenylphosphane)ferrocene) phosphanes and potassium dihydrobis(3-nitro-1,2,4-triazolyl)borate, K[H₂B(tz^NO2)₂]. These compounds have been characterized by elemental analyses, FT-IR, ESI-MS and multinuclear (¹H and ³¹P) NMR spectral data. The adduct {[H₂B(tz^NO2)₂]Ag[P(m-tolyl)₃]₂} has been characterized by single crystal X-ray studies. In the former, the H₂B(tz^NO2)₂ acts as a monodentate ligand utilizing the coordinating capability of only one of the additional (exo-) ring nitrogens to complete the coordination array about the silver atom.     

Poly(1,2,3-benzotriazolyl)borate complexes with copper(I) and tri-organophosphane: an unprecedented κ-coordination of [H2B(btz)2] (btz=1,2,3-benzotriazolyl) in the X-ray crystal structure of [Cu(PBn3)2{(btz)BH2(btz)}]

New copper(I) triorganophosphane derivatives [Cu(PR₃)_n{H₂B(btz)₂}] and [Cu(PR₃)_n{HB(btz)₃}] (n=1 or 2) have been synthesized from the reaction of CuCl with PR₃ (R=phenyl, cyclohexyl, benzyl, o-, m-, or p-tolyl) or PMePh₂ and potassium dihydrobis(1,2,3-benzotriazolyl)borate K[H₂B(btz)₂] or potassium hydrotris(1,2,3-benzotriazolyl)borate K[HB(btz)₃]. The complexes obtained have been characterized by elemental analyses and FT-IR in the solid state and by NMR (¹H and ³¹P{¹H}) spectroscopy and conductivity measurements in solution. Solution data are consistent with partial dissociation of complexes occurring throughout breaking of the CuP bond. Single crystal structural characterizations were undertaken for two of them. The structurally authenticated arrays are, (a) [Cu(PBn₃)₂{(btz)BH₂(btz)}] with a three coordinate P₂Cu(N) coordination sphere and the donor [H₂B(btz)₂] coordinated throughout only one N3 atom. (b) [Cu(P-m-tolyl₃)_n{(btz)₃BH}] with a four coordinate PCuN₃ coordination sphere with the tris(benzotriazolyl)borate acting as tripodal donor throughout all its N2 atoms.     

Copper(II) compounds of the planar-tridentate ligand 2,6-bis(pyrazol-3-yl)pyridine

The tridentate ligand 2,6-bis(pyrazol-3-yl)pyridine (dPzPy) renders coordination compounds with halide, nitrate and tetrafluoroborate salts of copper. The complexes, which have the form [Cu(dPzPy)X₂] with X=Br and Cl, [Cu(dPzPy)(NO₃)₂](H₂O), and [Cu(dPzPy)₂](BF₄)(SiF₆)_0.5(MeOH)₃ have been characterized by elemental analysis and by IR, EPR and ligand field spectroscopy. The single-crystal X-ray structure of [Cu(C₁₁H₉N₅)Br₂] shows the copper(II) ion to be coordinated by three N atoms of 2,6-bis(pyrazol-3-yl)pyridine and two bromides in a geometry exactly in between a trigonal-bipyramid and a square-pyramid. Each molecule lies on a crystallographic C₂-symmetry axis. They are coupled to one another by a two-dimensional network through NH to Br hydrogen bonds. The crystal structure of [Cu(C₁₁H₉N₅)Cl₂] is analogous to the bromide. The single-crystal X-ray structure of [Cu(dPzPy)₂](BF₄)(SiF₆)_0.5(MeOH)₃ shows the copper ion to be in a Jahn-Teller distorted octahedral N₆ environment of two mer-oriented tridentate ligands.     

Synthesis, crystal structure and vibrational spectroscopy of a novel mixed ligands Ni(II) pentaborate: [Ni(C4H10N2)(C2H8N2)2][B5O6(OH)4]2

A novel organic-inorganic hybrid pentaborate [Ni(C₄H₁₀N₂)(C₂H₈N₂)₂][B₅O₆(OH)₄]₂ has been synthesized by hydrothermal reaction and characterized by FT-IR, Raman spectroscopy, elemental analyses and DTA-TGA. Its crystal structure was determined from single crystal X-ray diffraction. The structure consists of isolated polyborate anion [B₅O₆(OH)₄]⁻ and nickel complex cation of [Ni(C₄H₁₀N₂)(C₂H₈N₂)₂]²⁺, in which the two kinds of ligands come from the decomposition of triethylenetriamine material. The [B₅O₆(OH)₄]⁻ units are connected to one another through hydrogen bonds, forming a three-dimensional framework with large channel along the a and c axes, in which the templating [Ni(C₄H₁₀N₂)(C₂H₈N₂)₂]²⁺ cations are located. The assignments of the record FT-IR absorption frequencies and Raman shifts were given.     

A general approach to the synthesis of neutral and cationic binuclear trithiocarbonato-bridged complexes of palladium(II) or of palladium(II)—platinum(II)

Addition (1:2) of Tl₂CS₃ to solutions of perchloratocomplexes of palladium(II) Pd(OClO₃)(C₆F₅)(PR₃) leads to neutral binuclear derivatives of the type (PR₃)(C₆F₅)Pd(μ-S₂CS)Pd(C₆F₅)(PR₃)₂, whilst the reaction of perchloratocomplexes of palladium(II) or platinum(II) with the neutral Pd(η²-CS₃)(PR₃)₂ affords cationic complexes of the type [L₂Pd(μ-S₂CS)M(C₆F₅)L₂]ClO₄ (M = Pd or Pt). Spectral data (IR and ³¹P, NMR) permit the inequivocal structural characterization of both the neutral and the cationic complexes.     

Synthesis and coordination chemistry of tripodal dialkyl[1,2-bis(diethylcarbamoyl)ethyl]phosphonates with lanthanide nitrates

Trifunctional dialkyl [1,2-bis(diethylcarbamoyl)- ethyl] phosphonates, (RO)₂P(O)CH[C(O)N(C₂H₅)₂]- [CH₂C(O)N(C₂H₅)₂] R  CH₃, C₂H₅, i-C₃H₇, n-C₆H₁₃ were prepared from the respective sodium salts, Na[(RO)₂P(O)CHC(O)N(C₂H₅)₂] and N,N- diethylchloroacetamide, and they were characterized by elemental analysis, mass, infrared and NMR spectroscopy. The molecular structure of (i-C₃H₇O)₂- P(O)CH[C(O)N(C₂H₅)₂][CH₂C(O)N(C₂H₅)₂] was determined by single crystal X-ray diffraction analysis and found to crystallize in the monoclinic space group P2₁/c with a=15.589(6), b=9.783(4), c= 16.283(7) Å, β = 110.90(3)°, Z = 4 and V= 2320(2) ų. The structure was solved by direct methods and blocked least-squares refinement converged with Rf = 5.7% and R_wF= 4.4% on 2266 unique data with F>4σ(F). Important bond distances include PO 1.459(3) Å, CHCO 1.228(3) Å and CHCH₂CO 1.223(3) Å. The coordination chemistry of the ligand with several lanthanides was examined, and the structure of the complex Gd(NO₃)₃{[(i-C₃H₇O)₂P(O)CH[C(O)N(C₂H₅)₂][CH₂C(O)N(C₂H₅)₂]}₂·H₂O was determined. The complex crystallized in the monoclinic space group P2₁/n with a = 13.524(5), b = 22.033(4), c = 19.604(4) Å β = 106.22(2)°, Z = 4 and V= 5609(3) ų. The structure was solved by heavy atom techniques and blocked least-squares refinement converged with R_F = 5.9% and R_wF = 4.1% on 5275 reflections with F > 4σ(F). Both trifunctional ligands were found to bond to Gd(III) through only the phosphoryl oxygen atoms. The remainder of the Gd coordination sphere was composed of three bidentate nitrate oxygen atoms and an oxygen bonded water molecule. Several important bond distances include GdO(phosphoryl)_av = 2.343(5) Å, GdO(nitrate)_av = 2.475(7) Å, GdO(water) = 2.354(5) Å, PO(phosphoryl)_av = 1.467(6) Å, CHCO_av = 1.242(10) Å and CHCH₂CO_av = 1.209(11) Å.     

Donor-substituted allenylidene(carbonyl)(XR3)chromium complexes (X=P, As, Sb) - synthesis and properties

Photolysis of the allenylidene pentacarbonyl chromium complexes [(CO)₅CrCCC(R¹)R²] (R¹=NMe₂, NPh₂; R²=NMe₂, OMe, Ph) in THF in the presence of equimolar amounts of XR₃ (XR₃=various phosphanes, P(OMe)₃, AsPh₃, SbPh₃) affords cis-allenylidene tetracarbonyl XR₃ complexes, cis-[(CO)₄(XR₃)CrCCC(R¹)R²]. When in the photolysis of [(CO)₅CrCCC(NMe₂)Ph], the phosphanes PR₃ (R=C₆H₄F-p, C₆H₄Cl-p, OMe) are used in excess (three equivalents) two carbonyl ligands are displaced and the mer-tricarbonyl complexes mer-[(CO)₃(PR₃)₂CrCCC(NMe₂)Ph] are formed both PR₃ ligands being mutually trans. The structure of the new complexes is established by IR, NMR, and UV-Vis spectroscopy, that of cis-[(CO)₄(PPh₃)CrCCC(NMe₂)Ph] additionally by an X-ray structural analysis. As indicated by the spectroscopic data of the compounds, these complexes are best described as hybrids of allenylidene and zwitterionic alkynyl complexes with delocalization of the electron pair at nitrogen bonded to the C_γ atom of the allenylidene ligand towards the metal center. The relative contribution of the allenylidene and zwitterionic alkynyl resonance forms is influenced by XR₃. Increasing the donor properties of XR₃ favors the allenylidene resonance form.     

Synthesis of metal paddlanes: X-ray structure determination of bis-(methyl nicotinate)copper(II) acetate dimer

The synthesis of nicotinic acid based N,N′-bidentate ligands capable of spanning the axial sites of copper(II) acetate dimer are reported. Reaction of these ligands with [Cu(C₂H₃0₂)₂]₂·2H₂0 gave the 1:1 adduct: a metal paddlane, which on recrystallization from MeOH/CHCl₃ yielded the trans-esterified complex [Cu(C₂H₃O₂)₂]₂·2C₇H₇N0₂, 3. A single crystal X-ray structure determination of 3 is presented.     

Novel ruthenium(II) diamine complexes

The complex cations [Ru(C₇H₁₆N₂)(C₁₀H₁₄)Cl]⁺, [Ru(C₇H₁₆N₂)(C₆H₆)Cl]⁺, [Ru(C₉H₁₈N₂)(C₆H₆)Cl]⁺, [Ru(C₉H₁₈N₂)(C₁₀H₁₄)Cl]⁺ and [Ru(C₁₄H₁₆N₂)(C₁₀H₁₄)Cl]⁺ have been synthesised from the reaction between the ruthenium-arene complexes [with C₆H₆ (benzene) or C₁₀H₁₄ (p-cymene)] and the respective chiral diamines [C₇H₁₆N₂=(S)-(−)-2-aminomethyl-1-ethylpyrrolidine, C₉H₁₈N₂=(S)-(+)-2-(pyrrolidinylmethyl)-pyrrolidine, or C₁₄H₁₆N₂=(1R,2R)-(+)-1,2-diphenylethylenediamine], isolated and characterised as chloride salts using single-crystal X-ray diffraction. All complexes were fully characterised by elemental analysis, mass spectrometry, ¹³C and ¹H NMR, and also found to exhibit catalytic activity in the transfer hydrogenation of acetophenone to 1-phenylethanol at 50 °C (enantiomeric excesses range from ca. 25% to 60%, and conversions from ca. 30% to 50%).     

Silver (I) poly(1,2,4-triazolyl)borate complexes containing monodentate phosphane ligands

New silver (I) derivatives containing monodentate tertiary phosphanes and anionic poly(triazol-1-yl)borate ligands have been prepared from the reaction of AgNO₃ and PR₃ (R = Ph, Bn, o-tolyl, m-tolyl, p-tolyl) and potassium dihydrobis(1,2,4-triazolyl)borate, K[H₂B(tz)₂], or potassium hydrotris(1,2,4-triazolyl)borate, K[HB(tz)₃]; their solid state and solution properties have been investigated through analytical and spectroscopic measurements (IR, ¹H-, and ³¹P NMR). The ¹H- and ³¹P NMR solution spectra in some cases can be interpreted on the basis of a dissociation of [{H₂B(tz)₂}Ag(PR₃)₂] into [{H₂B(tz)₂}Ag(PR₃)] and PR₃. All the compounds are soluble in chlorinated solvents and are non-electrolytes in CH₂Cl₂ and acetone solutions. [{H₂B(tz)₂}Ag(PPh₃)₂] and [{H₂B(tz)₂}Ag{P(m-tolyl)₃}₂] are simple mononuclear arrays, the silver atoms lying in four-coordinate N₂AgP₂ environments. Owing to the presence of the methyl substituents on the phosphane ligand, the complex [{HB(tz)₃}Ag{P(o-tolyl)₃}], as expected, is mononuclear. In [{H₂B(tz)₂}Ag{P(p-tolyl)₃}], the silver environment is still four-coordinate but PAgN₃, utilizing the coordinating capability of one of the additional (‘exo’-) ring nitrogens not only to complete the four-coordinate array about the silver but, necessarily, to link successive asymmetric units into a single-stranded polymer.     

Cationic copper(I) and silver(I) nitrile complexes with fluorinated weakly coordinating anions: Metal–nitrile bond strength and its influence on the catalytic performance

Copper(I) and silver(I) complexes of formulae [Cu(NCCH₃)₄]⁺[A]⁻ ([A]⁻ = [B(C₆F₅)₄]⁻ (1), {B[C₆H₃(CF₃)₂]₄}⁻ (2), [(C₆F₅)₃B–C₃H₃N₂–B(C₆F₅)₃]⁻ (3), and [Ag(NCCH₃)₄]⁺[B(C₆F₅)₄]⁻ (4) are examined with particular emphasis on the strength of their M–N bond and its influence on the catalytic performance of these complexes in cyclopropanation and aziridination. To examine the strength of the M–N interactions, vibrational spectra of the related hydrogenated and deuterated species [Cu(NCCH₃)₄]⁺, [Cu(NCCD₃)₄]⁺, [Ag(NCCH₃)₄]⁺, and [Ag(NCCD₃)₄]⁺ are also determined. It is found that the metal–nitrile bond strength is an important factor for the catalytic activity of the respective complexes.     

Synthesis,characterization and structure of cationic hydrides of rhodium(III). Part II. Crystal structure of dihydride(1,4-biscyclohexyl-diaza-1,3-butadiene)-bis(4-fluor-tristriphenylphosphine)rhodium(III) perchlorate

The reaction between [(R-DAB)Rh(PR₃)₂]⁺ and molecular hydrogen produces cationic cis-dihydride complexes of Rh(III), of general formula [RhH₂(R-DAB)(PR₃)₂]X. They are stable in air, 1:1 conductors and have been characterized by ¹H NMR, ³¹P NMR, IR and elemental analysis. The tertiary phosphines employed were: PPh₃, P(p-C₆H₄F)₃, PMePh₂, PEt₃, and the R-DAB ligands (RN:CR′CR′:NR)¹, Ph-DAB, c-Hex-DAB, NH₂-DAB(CH₃,CH₃), t-but-DAB.The structure of [RhH₂(c-Hex-DAB){P(p-C₆H₄F)₃}₂]ClO₄ has been determined by an X-ray diffraction study. Crystals are orthorhombic, space group Pbnm. Unit cell parameters are: a = 13.032(1), b = 18.166(2), c = 21.449(2) Å, Z = 4, R = 0.081, R_w = 0.082 for 2906 reflections, with I> 3σ(I) the rhodium atom is octahedrally coordinated with the two hydride-hydrogens and c-Hex-DAB in the equatorial plane; the two phosphine ligands are in an axial position bent towards the hydrogens making an angle of 164.9(4)°.     

Heteroligand copper(I) complexes of N-thiophosphorylated thioureas and phosphanes: Versatile structures and luminescence

Reaction of the potassium salts of (EtO)₂P(O)CH₂C₆H₄-4-(NHC(S)NHP(S)(OiPr)₂) (HL^I), (CH₂NHC(S)NHP(S)(OiPr)₂)₂ (H₂L^II) or cyclam(C(S)NHP(S)(OiPr)₂)₄ (H₄L^III) with [Cu(PPh₃)₃I] or a mixture of CuI and Ph₂P(CH₂)_1-3PPh₂ or Ph₂P(C₅H₄FeC₅H₄)PPh₂ in aqueous EtOH/CH₂Cl₂ leads to [Cu(PPh₃)L^I] (1), [Cu₂(Ph₂PCH₂PPh₂)₂L^II] (2), [Cu{Ph₂P(CH₂)₂PPh₂}L^I] (3), [Cu{Ph₂P(CH₂)₃PPh₂}L^I] (4), [Cu{Ph₂P(C₅H₄FeC₅H₄)PPh₂}L^I] (5), [Cu₂(PPh₃)₂L^II] (6), [Cu₂(Ph₂PCH₂PPh₂)L^II] (7), [Cu₂{Ph₂P(CH₂)₂PPh₂}₂L^II] (8), [Cu₂{Ph₂P(CH₂)₃PPh₂}₂L^II] (9), [Cu₂{Ph₂P(C₅H₄FeC₅H₄)PPh₂}₂L^II] (10), [Cu₈(Ph₂PCH₂PPh₂)₈L^IIII₄] (11), [Cu₄{Ph₂P(CH₂)₂PPh₂}₄L^III] (12), [Cu₄{Ph₂P(CH₂)₃PPh₂}₄L^III] (13) or [Cu₄{Ph₂P(C₅H₄FeC₅H₄)PPh₂}₄L^III] (14) complexes. The structures of these compounds were investigated by IR, ¹H, ³¹P{¹H} NMR spectroscopy; their compositions were examined by microanalysis. The luminescent properties of the complexes 1-14 in the solid state are reported.     

Zinc(II) and copper(II) 1D coordination polymeric complexes of a reduced Schiff base ligand

The reaction of Zn(ClO₄)₂ · 6H₂O and Cu(ClO₄)₂ · 6H₂O with H₃Sas (H₃Sas = N-(2-hydroxybenzyl)-L-aspartic acid in water afforded the complexes [Zn₆(Sas)₄(H₂O)₈]·5H₂O (1) and [Cu(HSas)(H₂O)] (2), respectively, which were characterized by infrared spectroscopy, elemental analysis, thermogravimetry and single-crystal X-ray crystallography. In 1, the pentanuclear clusters formed by four H₃Sas ligands and five Zn(II) metal ions are bridged by the “[Zn(H₂O)₄]²⁺” cations to form 1D polymeric chains. While in 2, the mononuclear [Cu(HSas)(H₂O)] repeating units form a 1D zigzag chain and further extended by strong intermolecular hydrogen bonds to form a 2D sheet. The different coordination geometries of Cu(II) and Zn(II) show significant influence on the polymeric structures.     

On the identification of ionic species of neutral halogen dimers, monomers and pincer type palladacycles in solution by electrospray mass and tandem mass spectrometry

Electrospray (ESI) mass spectra analysis of acetonitrile solutions of a series of neutral chloro dimers, pincer type, and monomeric palladacycles has enabled the detection of several of their derived ionic species. The monometallic cationic complexes Pd[κ¹-C,κ¹-N,κ¹-S-C(CH₃S-2-C₆H₄)C(Cl)CH₂N(CH₃)₂]⁺ (1a) and [Pd[κ¹-C,κ¹-N,κ¹-S-C(CH₃S-2-C₆H₄)C(Cl)CH₂N(CH₃)₂](CH₃CN)]⁺ (1b) and the bimetallic cationic complex [κ¹-C,κ¹-N,κ¹-S-C(CH₃S-2-C₆H₄)C(Cl)CH₂N(CH₃)₂]Pd-Cl-Pd[κ¹-C,κ¹-N,κ¹-S-C(CH₃S-2-C₆H₄)C(Cl)CH₂N(CH₃)₂]⁺ (1c) were detected from an acetonitrile solution of the pincer palladacycles Pd[κ¹-C,κ¹-N,κ¹-S-C(CH₃S-2-C₆H₄)C(Cl)CH₂N(CH₃)₂](Cl) 1. For the dimeric compounds {Pd[κ¹-C,κ¹-N-C(Y-2-C₆H₄)C(Cl)CH₂N(CH₃)₂](μ-Cl)}₂ (2, Y=H and 3, CF₃), highly electronically unsaturated palladacycles [Pd[κ¹-C,κ¹-N-C(Y-2-C₆H₄)C(Cl)CH₂N(CH₃)₂]⁺ (2d, 3d) and their mono and di-acetonitrile adducts, namely, [Pd[κ¹-C,κ¹-N-C(Y-2-C₆H₄)C(Cl)CH₂N(CH₃)₂](CH₃CN)]⁺ (2e, 3e) and [Pd[κ¹-C,κ¹-N-C(Y-2-C₆H₄)C(Cl)CH₂N(CH₃)₂](CH₃CN)₂]⁺ (2f and 3f) were detected together with the bimetallic complex [Pd[κ¹-C,κ¹-N-C(Y-2-C₆H₄)C(Cl)CH₂N(CH₃)₂]-Cl-Pd[κ¹-C,κ¹-N-C(Y-2-C₆H₄)C(Cl)CH₂N](CH₃)₂]⁺ (2a, 3a) and its acetonitrile adducts [κ¹-C,κ¹-N-C(Y-2-C₆H₄)C(Cl)CH₂N(CH₃)₂](CH₃CN)Pd-Cl-Pd[ κ¹-C,κ¹-N-C(Y-2-C₆H₄)C(Cl)CH₂N(CH₃)₂]⁺ (2b, 3b) and [κ¹-C,κ¹-N-C(Y-2-C₆H₄)C(Cl)CH₂N(CH₃)₂](CH₃CN)Pd-Cl-Pd[κ¹-C, κ¹-N-C(Y-2-C₆H₄)C(Cl)CH₂N(CH₃)₂(CH₃CN)]⁺ (2c, 3c). The dimeric palladacycle {Pd[κ¹-C,κ¹-N-C(CH₃O-2-C₆H₄)C(Cl)CH₂N(CH₃)₂](μ-Cl)}₂ (4) is unique as it behaves as a pincer type compound with the OCH₃ substituent acting as an intramolecular coordinating group which prevents acetonitrile full coordination, thus forming the cationic complexes [(C₆H₄(o-CH₃O)CC(Cl)CH₂N(CH₃)₂-κO,κC,κN)Pd]⁺ (4b), [(C₆H₄(o-CH₃O)CC(Cl)CH₂N(CH₃)₂- κO,κC,κN)Pd(CH₃CN)]⁺ (4c) and [(C₆H₄ (o-MeO)CC(Cl)CH₂N(CH₃)₂-κO, κC,κN)Pd-Cl-Pd(C₆H₄(o-CH₃O)CC(Cl)CH₂N(CH₃)₂-κO,κC,κN)]⁺ (4a). ESI-MS spectra analysis of acetonitrile solutions of the monomeric palladacycles Pd[κ¹-C,κ¹-N-C(Y-2-C₆H₄)C(Cl)CH₂N(CH₃)₂](Cl)(Py) (5, Y=H and 6, Y=CF₃) allows the detection of some of the same species observed in the spectra of the dimeric palladacycles, i.e., monometallic cationic 2d-3d, 2e-3e and {Pd[κ¹-C,κ¹-N-C(Y-2-C₆H₄)C(Cl)CH₂N(CH₃)₂](Py)}⁺ (5a, 6a) and {Pd[κ¹-C,κ¹-N-C(Y-2-C₆H₄)C(Cl)CH₂N(CH₃)₂](CH₃CN)(Py)}⁺ (5b, 6b) and the bimetallic 2a, 3a, 2b, 3b, 2c and 3c. In all cationic complexes detected by ESI-MS, the cyclometallated moiety was intact indicating the high stability of the four or six electron anionic chelate ligands. The anionic (chloride) or neutral (pyridine) ligands are, however, easily replaced by the acetonitrile solvent.     

Tertiary phosphine complexes of nickel(0) and nickel(I). New dinitrogen complexes of nickel(0)

The reduction of NiX₂(PCy₃)₂ (X = Cl, Br; PCy₃ = tricyclohexylphosphine) in toluene with sodium sand under argon affords [NiX(PCy₃)₂]₂ or Ni(PCy₃)₃. In the same way starting from NiX₂P₂ [X = Cl, Br; P = P(C₂H₅)₃, P(CH₂CH₂CH₂CH₃)₃, P(C₂H₅)₂ C₆H₅] the tetracoordinate Ni(0) complexes NiP₄ are obtained. These give NiP₃(N₂) under nitrogen. The electronic spectra of Ni(0) and Ni(I) complexes, both in the solid state and solution, are reported.     

Synthesis and X-ray structures of rhenium(I) carbonyl aminoalkoxide and aminocarboxylate complexes

The complexes [Re{MeN(CH₂CH₂O)(CH₂CH₂OH)-κ³N,O,O}(CO)₃] (1), [Re{N(CH₂CH₂O)(CH₂CH₂OH)₂-κ³N,O,O}(CO)₃] (2), [Me₃NH]₂[(OC)₃Re{N(CH₂CO₂)₂-κ³N,O,O}CH₂CH₂{N(CH₂CO₂)₂-κ³N,O,O}Re(CO)₃] (3), [Me₃NH]₂[Re₂{μ₂-2,6-(O₂C)₂(C₅H₃N)-κ³N,O,O}₂(CO)₆] (4) and [Re₂{μ₂-2,6-(OCH₂)(C₅H₃N)(CH₂OH)-κ²N,O}₂(CO)₆] (5) were synthesized in high yields via the reactions of [Re₂(CO)₁₀] and Me₃NO with MeN(CH₂CH₂OH)₂, N(CH₂CH₂OH)₃, EDTA, pyridine-2,6-dicarboxylic acid and pyridine-2,6-dimethanol, respectively. Complexes 1-5 were characterized by IR and ¹H NMR spectroscopy, elemental analysis and X-ray crystallography.     

Synthesis and characterization of silver(I) derivatives containing acylpyrazolonate and phosphino ligands: X-ray crystal structures of monomeric [Ag(Q)(PPh3)2] and of dimeric [{Ag(Q)(PiBu3)}2] (Q = 1-phenyl-3-methyl-4-tert-butylacetylpyrazolon-5-ato)

New silver(I) acylpyrazolonate derivatives [Ag(Q)], [Ag(Q)(PR₃)]₂ and [Ag(Q)(PR₃)₂] (HQ = 1-R¹-3-methyl-4-R²(CO)pyrazol-5-one, HQ^Bn = R¹ = C₆H₅, R² = CH₂C₆H₅; HQ^CHPh2 = R¹ = C₆H₅, R² = CH(C₆H₅)₂; HQ^nPe = R¹ = C₆H₅, R² = CH₂C(CH₃)₃; HQ^tBu = R¹ = C₆H₅, R² = C(CH₃)₃; HQ^fMe = R¹ = C₆H₄-p-CF₃, R² = CF₃; HQ^fEt = R¹ = C₆H₅, R² = CF₂CF₃; R = Ph or iBu) have been synthesized and characterized in the solid state and solution. The crystal structure of 1-(4-trifluoromethylphenyl)-3-methyl-5-pyrazolone, the precursor of proligand HQ^fMe and of derivatives [Ag(Q^nPe)(PPh₃)₂] and [Ag(Q^nPe)(PiBu₃)]₂ have been investigated. [Ag(Q^nPe)(PPh₃)₂] is a mononuclear compound with a silver atom in a tetrahedrally distorted AgO₂P₂ environment, whereas [Ag(Q^nPe)(PiBu₃)]₂ is a dinuclear compound with two O₂N-exotridentate bridging acylpyrazolonate ligands connecting both silver atoms, their coordination environment being completed by a phosphine ligand.     

Pyridine and phosphine reactions with [CPh3][B(C6F5)4]

Trityl borate salts [4-RPyCPh₃][B(C₆F₅)₄] (R = H 1, ^tBu 2, Et 3, NMe₂4) and [R₃PCPh₃][B(C₆F₅)₄] (R = Me 5, ⁿBu 6, Ph[1] 7, p-MeC₆H₄8) are readily prepared via equimolar reaction of the appropriate pyridine or phosphine and trityl borate [CPh₃][B(C₆F₅)₄]. The analogous reactions of PⁱPr₃ affords the product [(p-ⁱPr₃P-C₆H₄)Ph₂CH][B(C₆F₅)₄] (9) while the corresponding reactions of Cy₃P and ^tBu₃P gave the cyclohexadienyl derivatives [(p-R₃PC₆H₅)CPh₂][B(C₆F₅)₄] (R = Cy 10, ^tBu 11). X-ray structures of 5 and 9 are reported.