Silver(I) complexes of bis[2-(diphenylphosphino)phenyl] ether

The reaction of AgOTf in dichloromethane with bis(2-(diphenylphosphino)phenyl) ether (DPEphos) in an equimolar ratio afforded a dinuclear complex [Ag₂(κ²-P,P′-DPEphos)₂(μ-OTf)₂] (1), whereas the similar reaction in a 1:2 molar ratio resulted in the formation of a bis-chelating complex [Ag(κ²-P,P′-DPEphos)₂][OTf] (2). The silver(I) complex 1 was obtained as a dimer, in which two silver atoms are bridged by two triflate groups to form three adjacent eight-membered spirocyclic rings. The mixed-ligand complex [Ag(κ²-P,P′-DPEphos)(2,2′-bpy)][OTf] (3) was obtained in the reaction of 1 in dichloromethane with 2,2′-bipyridine. The crystal structures of complexes 1–3 were determined by single crystal X-ray analyses.     

Synthesis and characterization of novel platinum group metal complexes of bis[2-(diphenylphosphino)ethyl]amine

A mixed donor tridentate ligand bis[2-(diphenylphosphino)ethyl]amine (DPEA) was synthesized in its hydrochloride form by a modified procedure and characterized by ¹H, ¹³C and ³¹P NMR spectral data. Reaction of RhCl(CO)(PPh₃)₂ with DPEA · HCl and NaBPh₄ in methanol gave the cationic Rh(I) complex [Rh(DPEA)PPh₃IBPh₄ but the reaction of IrCl(CO)(PPh₃)₂ with DPEA · HCl in boiling benzene gave a unique complex, [Ir(H)(Cl)(CO)(DPEA)]Cl, in which five different donor atoms are coordinated to the single Ir(III) ion. A neutral, RH(III) complex of the composition [RhCl₃(DPEA)] was prepared by the reaction of RhCl₃ · xH₂O with DPEA · HCl in methanol. Reaction of PdCl₂(COD) with DPEA · HCl in benzene or methanol gave the cationic complex [PdCl(DPEA)]Cl the above reaction conducted in benzene-acetone-methanol mixture gave the 1:2 complex [Pd(DPEA)₂]Cl₂. A novel trinuclear Pt(II) complex of the composition [Pt₃Cl₃(DPEA)₃]Cl₃ was prepared by the reaction of K₂PtCl₄ and DPEA · HCl in water-acetone mixture. Reaction of K₂PtCl₄, DPEA · HCl and NH₄PF₆ in water ethanol mixture gave the binuclear, cationic complex, [Pt₂(DPEA)₃](PF₆)₄. All the complexes were characterized by elemental analysis, conductivity, ¹H and ³¹P NMR spectral data.     

Group 12 metal complexes of [26]hexaphyrin(1.1.1.1.1.1)

Metalation of meso-hexakis(pentafluorophenyl)-substituted [26]hexaphyrin(1.1.1.1.1.1) (1) has been explored with group 12 metal ions Zn(II), Cd(II), and Hg(II). Zn(II) and Cd(II) ions afforded dinuclear gable-shaped complexes 2 and 3 in good yields, while Hg(II) ion provided bis-Hg(II) and mono-Hg(II) planar complexes (4 and 5) via C-H bond cleavage.     

Some transition metal complexes of new terdentate ligands: Bis[2-(diphenylphosphino)ethyl]benzylamine and bis[2-(diphenylarsino)ethyl)benzylamine

Complexes of the terdentate ligands bis[2-diphenylphosphino)ethyl]benzylamine (DPBA) and bis[2-(diphenylarsino)ethyl]benzylamine (DABA) with Co(II), Ni(II), Pd(II), Pt(II), Rh(III), Ir(III), Rh(I) and Ir(I) are reported. The ligand DPBA reacts with Co(II) ion to form two types of complexes: a high-spin, paramagnetic, tetrahedral Co(II) complex of composition [CoCl(DPBA)]Cl and a low-spin, paramagnetic, square-planar complex of composition [CoBr(DPBA)]B(C₆H₅)₄. The reaction of DPBA with Ni(II) ion in methanol yields low-spin, diamagnetic, square-planar complexes of type [NiX(DPBA)]Y [X = Cl, Br or I; Y = Cl or B(C₆H₅)₄]. Four-coordinate, square-planar, cationic complexes of type [MY(L⁺[M = Pd(II), Pt(II), Rh(I) or Ir(I); Y = Cl or P(C₆H₅)₃; L = DPBA or DABA], were obtained on reaction of L with various starting materials containing these metal ions. Reaction of DPBA and DABA with rhodium and iridium trichlorides gave octahedral, neutral complexes of general formula [MCl₃(L)] (M = Rh or Ir, L = DPBA or DABA). All the complexes were characterized on the basis of their elemental analysis, molarconductance data, magnetic susceptibilities, electronic spectra, IR spectral measurements, and¹H and³¹P-{¹H} NMR spectral data.     

Extended-chain, multinuclear transition metal complexes bridged by cyanodiazenido(1-), [N=N-C[triple bond, length as m-dash]N]-, ligands

Extended-chain complexes containing multiple transition metal centres linked by conjugated micro-cyanodiazenido(1-) ligands [N=N-C[triple bond, length as m-dash]N]- have been obtained by reaction of trans-[BrW(dppe)2(N2CN)], , [dppe=1,2-bis(diphenylphosphino)ethane] with dirhodium(II) tetra-acetate, bis(benzonitrile)palladium(II) dichloride, and bis(aqua)M(II) bis(hexafluoroacetylacetonate) (M=Mn, Ni, Cu, Zn): stronger Lewis acids such as tetrakis(acetonitrile)palladium(II) tetrafluoroborate and boron trifluoride promote hydrolysis of complex , leading to the isolation of a novel carbamoylhydrazido(2-) complex, trans-[BrW(dppe)2(N2HC=ONH2)]+[BF4]-.     

Cyclic M2(RL)2 coordination complexes of 5-(3-[N-tert-Butyl-N-aminoxyl]phenyl)pyrimidine with paramagnetic transition metal dications

5-(3-(N-tert-Butyl-N-aminoxyl)phenyl)pyrimidine (RL = 3NITPhPyrim) forms isostructural cyclic M2(RL)2 cyclic dimers with M(hfac)2 (M = Mn, Co, Cu; hfac = hexafluoroacetylacetonate). Mn2(hfac)4(RL)2 exhibits strong antiferromagnetic Mn-RL exchange, with weak ferromagnetic exchange (0.7 cm(-1)) between Mn-RL units that is consistent with a spin polarization exchange mechanism. The magnetic moment of Co2(hfac)4(RL)2 at higher temperatures is consistent with strongly antiferromagnetic exchange within the Co-NIT units and tends toward zero below 50 K at lower magnetic fields. Cu2(hfac)4(RL)2 shows more complex behavior, with no high-temperature plateau in chiT(T) up to 300 K but a monotonic decrease down to about 100 K. The Cu(II)-nitroxide bonds decrease by 0.2-0.3 A over the same temperature range, corresponding to a change of nitroxide coordination from axial to equatorial. This thermally reversible Jahn-Teller distortion leads to a thermally induced spin state conversion from a high-spin, paramagnetic state at higher temperature to a low-spin state at lower temperature. This spin state conversion is accompanied by a reversible solid-state thermochromic change between dull yellow-brown at room temperature and green at 77 K.     

Organometallic ligands : II. The coordination chemistry of 1-[(dimethylamino)-methyl]-2-(diphenylphosphino)ferrocene

Complexes of the organometallic ligand (h⁵-C₅H₅)Fe[(h⁵-C₅H₃)(1-CH₂NMe₂)(2-PPh₂)] (FcCNP) have been prepared with the carbonyls of chromium, molybdenum, tungsten, iron, and cobalt and with borane. With the Group VIB metals, the ligand forms complexes of the type (FcCNP)M(CO)₄ in which the FcCNP ligand is chelating. However, in the case of (FcCNP)Fe(CO)₄ and [(FcCNP)₂Co(CO)₃]BPh₄ the ligand is monodentate, the phosphorus acting as the donor atom. Infrared and NMR data were used to establish the mode of coordination in each case. The electrochemistry of the Group VIB metal carbonyl complexes has been investigated, the chromium complex being of particular interest. The cyclic voltammogram of (FcCNP)Cr(CO)₄ consists of two, reversible, one electron redox waves at E_{peak, anodic} + 0.54 V and + 0.96 V (vs. SCE in CH₂Cl₂), and a third, irreversible wave at E_{peak, anodic} + 1.47 V. At + 0.54 V the solution color changed from yellow to orange and the v(CO) bands shifted from 2011 w, 1891 s, and 1831 s (cm^?1) in the neutral complex to 2080 m, 2000 s, and 1970 s (cm^?1) in the singly oxidized species. At + 0.96 V, the color changed further to blue-green, but no additional shift in v(CO) was observed. On the basis of this information, it is concluded that the first redox wave represents the process Cr⁰ → Cr⁺ and the second wave Fe²⁺ → Fe³⁺. Other aspects of the electrochemistry of the Group VIB metal carbonyl complexes are discussed.     

31P NMR spectra and the metal—metal bond strength in some bis-μ?-[bis(diphenylphosphino)methane]diplatinum complexes

It is proposed that the magnitudes of the³¹P³¹P and¹⁹⁵Pt³¹P long-range coupling constants in the title complexes may provide a measure of the strength of the PtPt bonding.     

Coordination complexes of 1-(4-[N-tert-butyl-N-aminoxyl]phenyl)-1H-1,2,4-triazole with paramagnetic transition metal dications

1-(4-(N-tert-Butyl-N-aminoxylphenyl))-1H-1,2,4-triazole (NIT-Ph-Triaz) forms isostructural cyclic 2:2 dimeric complexes with M(hfac)(2), M = Mn, Ni, Co, hfac = hexafluoroacetylacetonate. For M = Cu, only a sufficient sample for crystallographic analysis was isolated. For M = Mn, Ni, and Co, the M-NIT exchange is strongly antiferromagnetic. The intradimer exchange coupling between M-NIT units is J/k = +0.53 K for M = Mn, J/k = (-)3.5 K for M = Ni. For M = Co, J/k < 0 K, with the magnetic susceptibility tending toward zero at low temperatures. The exchange behavior is consistent with an intradimer spin polarization mechanism linking M-NIT units through the conjugated pi-system of the radical. Computational modeling of NIT-Ph-Triaz gives Mulliken spin populations in good accord with experimental electron spin resonance hyperfine coupling constants, and is consistent with the presumed radical spin density distribution in the complexes. The results provide useful guidelines to anticipate spin polarization effects in organic pi-radical building blocks in magnetic materials, particularly when qualitative connectivity-based analyses are clouded by nonalternant molecular connectivities.     

Isomerization of N-[α-(Alkylthio)alkyl]- and N-[α-(Arylthio)alkyl]benzotriazoles

The thermal isomerizations of N-[α-(alkylthio)alkyl]- and N-[α-(arylthio)alkyl]benzotriazoles have been investigated under N₂ atmospheres (i) in toluene, xylene, MeOH, or EtOH, in the presence of acid catalysts and (ii) in the absence of solvent. The sulfide isomerization rates depend on the number of H-atoms carried by the C-atom attached to the N-atom of the benzotriazole: tertiary (no hydrogen) > secondary (1 hydrogen) > primary (2 hydrogens). The results support an isomenzation mechanism involving a heterolytic N? C bond cleavage with formation of sulfonium/carbonium and benzotriazolate ions.     

Synthesis, coordination and catalytic use of 1-(diphenylphosphino)-1'-carbamoylferrocenes with pyridyl-containing N-substituents

Ferrocene phosphinocarboxamides, 1-(diphenylphosphino)-1'-{N-[(2-pyridyl)methyl]carbamoyl}ferrocene (1) and 1-(diphenylphosphino)-1'-{N-[2-(2-pyridyl)ethyl]carbamoyl}ferrocene (2) were prepared from 1-(diphenylphosphino)-1'-ferrocenecarboxylic acid and studied as ligands for palladium. Starting with [PdCl2(cod)], the reactions at a 2 : 1 ligand-to-metal ratio gave uniformly the bis-phosphine complexes [PdCl2(L-kappaP)2] (3, L = 1; 4, L = 2) whereas those performed at a 1 : 1 ratio yielded distinct products: [PdCl2(1-kappa(2)P,N)] (5) with 1 coordinating as a trans-spanning P,N-donor, and the symmetric, P,N-bridged dimer [(micro-2-N,P)2{PdCl2}2] (6), respectively. The crystal structures of 1, 2, 4.4CHCl3, 5.AcOH, and 6.8CHCl3 as determined by X-ray diffraction showed the compounds to form well defined solid-state assemblies through hydrogen bonds. Testing of the phosphinocarboxamides in the palladium-catalysed Suzuki cross-coupling reaction revealed 1 and 2, combined with Pd(OAc)2 to form efficient catalysts for the reactions of aryl bromides while aryl chlorides coupled only when activated with electron-withdrawing groups.     

Syntheses and crystal structures of organoindium(III) 1-D coordination polymers with bis(diphenylphosphino)alkane dioxides

Abstract

Bromomethyl-dibromo-indium(III), Br₂InCH₂Br, obtained from indium monobromide and methylene dibromide, reacts with hard and soft donor ligands to afford the corresponding indium(III) organometallic complexes. In this work, we investigated the conditions to prepare adducts of Br₂InCH₂Br using bis(diphenylphosphino)alkane dioxides acting as hard ligands. We report here the synthesis and crystal structures of two 1-D coordination polymers with the hard donor ligands Ph₂P(O)(CH₂)_mP(O)Ph₂ (m = 2, dppeO₂ and m = 6, dpphO₂). Compounds 1 and 2 with formulas [Br₂In(CH₂Br)(dppeO₂)]_n (1) and [Br₂In(CH₂Br)(dpphO₂)]_n (2) were characterized by IR and Raman spectroscopy and elemental analysis. We also obtained an ionic indium(III) compound with dppeO₂ acting as a chelating ligand with formula [InBr₂(dppeO₂)₂][InBr₃(CH₂Br)] (3). The crystal structures were determined for 1–3 using single crystal X-ray diffractometry. The geometry around the In(III) can be described as a trigonal bipyramid in 1 and 2, and the chains were packed onto the plane giving layers that are stabilized mainly by intermolecular interactions. Compound 3 has a square bipyramidal In(III) cation with formula [Br₂L₂In]⁺ and tetrahedral organoindium(III) anion with formula [Br₃InCH₂Br]^–. Hirshfeld surface analysis employing 2-D fingerprint plots have been used to analyze intramolecular and intermolecular interactions present in the solid state of the structures.     

Polymer complexes. XXXX. Supramolecular assembly on coordination models of mixed-valence-ligand poly[1-acrylamido-2-(2-pyridyl)ethane] complexes

The build-up of polymer metallic supramolecules based on homopolymer (1-acrylamido-2-(2-pyridyl)ethane (AEPH)) and ruthenium, rhodium, palladium as well as platinum complexes has been pursued with great interest. The homopolymer shows three types of coordination behaviour. In the mixed valence paramagnetic trinuclear polymer complexes [(11)+(12)] in the paper and in mononuclear polymer complexes (1)-(5) it acts as a neutral bidentate ligand coordinating through the N-pyridine and NH-imino atoms, while in the mixed ligand diamagnetic poly-chelates, which are obtained from the reaction of AEPH with PdX2 and KPtCl4 in the presence of N-heterocyclic base consisting of polymer complexes (9)+(10), and in monouclear compounds (6)-(8), it behaves as a monobasic bidentate ligand coordinating through the same donor atoms. In mononuclear compounds (13)+(14) it acts as a monobasic and neutral bidentate ligand coordinating only through the same donor atoms. Monomeric distorted octahedral or trimeric chlorine-bridged, approximately octahedral structures are proposed for these polymer complexes. The poly-chelates are of 1:1, 1:2 and 3:2 (metal-homopolymer) stoichiometry and exhibit six coordination. The values of ligand field parameters were calculated. The homopolymer and their polymer complexes have been characterized physicochemically.     

Ambidentate Properties of Asymmetric Substituted Imidazoles. Direction of Benzylation of 2-[N-(4-Chlorophenyl)carbamoyl]methylthio-4-phenyl-1H-imidazole

On the basis of ¹H-¹H two dimensional NMR spectroscopy (NOESY) it has been unambiguously shown that the benzylation of 2-[N-(4-chlorophenyl)carbamoyl]methylthio-4-phenyl-1H-imidazole occurs at the N₍₁₎ atom. This data was confirmed by comparison of the properties of the alkylation product obtained with the corresponding N₍₃₎-benzylimidazole isomer synthesized independently. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 882–886, June, 2005.     

Polymer complexes. LV. Spectroscopic,thermal studies,and coordination of metal ions N-[3-(5-amino-1,2,4-triazolo)] acrylamide polymer complexes

Novel polymeric complexes with a potentially bidentate ligand formed by amidation of 3,5-diamino-1,2,4-triazole with acryloyl chloride were synthesized and characterized on the basis of elemental analyses, IR, ¹H-NMR, UV-Vis, magnetic susceptibility measurements, molar conductance, and thermal analyses. The molar conductance data reveal that all the polymer complexes are non-electrolytes. Spectral studies reveal that the free ligand coordinates bidentate to the metal ion through the oxygen of the carbonyl and azomethine of the heterocyclic ring. Elemental analyses of the polychelates indicate the metal to ligand ratio of 1?:?1/1?:?2. On the basis of electronic spectral data and magnetic susceptibility measurements, suitable geometry has been proposed for each polymeric complex. The electron spin resonance spectral data of the Cu(II) complex showed that the metal–ligand bonds have considerable covalent character. The thermal behavior of these chelates shows that the polymer complexes lose coordinated water in the first step immediately followed by decomposition of the anions and ligand molecules in a subsequent step.