Synthesis,structure, and magnetic properties of bis (3-amino-2-chloropyridinium)tetrahalocuprate(II) [halide = Cl or Br]

The reaction of CuX₂ (X = Cl or Br) with 3-amino-2-chloropyridine in aqueous acids (HX; X = Cl or Br) yields bis(3-amino-2-chloropyridinium)tetrachlorocuprate(II) and bis(3-amino-2-chloropyridinium)tetrabromocuprate(II). Both compounds have been characterized by IR, powder X-ray diffraction, single-crystal X-ray diffraction and temperature dependent magnetic susceptibility. The compounds are isomorphous and exhibit weak antiferromagnetic interactions.     

Comparison of the structure and magnetic order in a series of layered Ni(II) organophosphonates, Ni[(RPO3)(H2O)] (R = C6H5, CH3, C18H37)

The reaction of nickel chloride with phenyl phosphonic acid under hydrothermal conditions resulted in the isolation of yellow-green single crystals of Ni[(C(6)H(5)PO(3))(H(2)O)]. The structure of the compound has been solved by X-ray single-crystal diffraction studies. Ni[(C(6)H(5)PO(3))(H(2)O)] crystallizes in the orthorhombic space group Pmn2(1) and is isostructural with the Mn(II), Fe(II), and Co(II) analogues. It presents the typical features of the hybrid 2D structures, consisting of alternating inorganic and organic layers. The former are formed by six-coordinated nickel(II) ions bridged by oxygen atoms into the layers. The inorganic layers are capped by the phenyl phosphonate groups, with phenyl groups of two adjacent ligands forming a hydrophobic bilayer region, and van der Waals contacts are established between them. The magnetic properties investigated by means of dc and ac susceptibility measurements point to an AF exchange coupling between nearest neighboring Ni(II) ions. Below 5 K, the compound orders magnetically showing the typical features of a canted antiferromagnet. The magnetic behavior and magnetic dimensionality of Ni[(C(6)H(5)PO(3))(H(2)O)] have been fully analyzed and compared to those of the Ni(II) parent compounds Ni[(RPO(3))(H(2)O)] (where R = CH(3), C(18)H(37)), which exhibit different symmetries of the inorganic layers and lengths of the R groups.     

Synthesis,Structure and Characterization of Three Metal Molybdate Hydrates: Fe(H2O)2(MoO4)2·H3O,NaCo2(MoO4)2(H3O2)and Mn2(MoO4)3·2H3O

Three metal molybdate hydrates,Fe(H2O)2(MoO4)2·H3O(FeMo),NaCo2(MoO4)2(H3O2)(CoMo)and Mn2(MoO4)3·2H3O(MnMo),were synthesized by the mixed-solvent-thermal methods and characterized by singlecrystal X-ray...     

Electronic structure, excited states, and photoelectron spectra of uranium, thorium, and zirconium bis(Ketimido) complexes (C5R5)2M[-NCPh2]2 (M = Th, U, Zr; R = H, CH3)

Organometallic actinide bis(ketimide) complexes (C5Me5)2An[-N=C(Ph)(R)]2 (where R = Ph, Me, and CH2Ph) of thorium(IV) and uranium(IV) have recently been synthesized that exhibit chemical, structural, and spectroscopic (UV-Visible, resonance-enhanced Raman) evidence for unusual actinide-ligand bonding. [Da Re et al., J. Am. Chem. Soc., 2005, 127, 682; Jantunen et al., Organometallics, 2004, 23, 4682; Morris et al., Organometallics, 2004, 23, 5142.] Similar evidence has been observed for the group 4 analogue (C5H5)2Zr[-N=CPh2]2. [Da Re et al., J. Am. Chem. Soc., 2005, 127, 682.] These compounds have important implications for the development of new heavy-element systems that possess novel electronic and magnetic properties. Here, we have investigated M-ketimido bonding (M = Th, U, Zr), as well as the spectroscopic properties of the highly colored bis-ketimido complexes, using density functional theory (DFT). Photoelectron spectroscopy (PES) has been used to experimentally elucidate the ground-state electronic structure of the thorium and uranium systems. Careful examination of the ground-state electronic structure, as well as a detailed modeling of the photoelectron spectra, reveals similar bonding interactions between the thorium and uranium compounds. Using time-dependent DFT (TDDFT), we have assigned the bands in the previously reported UV-Visible spectra for (C5Me5)2Th[-N=CPh2]2, (C5Me5)2U[-N=CPh2]2, and (C5H5)2Zr[-N=CPh2]2. The low-energy transitions are attributed to ligand-localized N p --> C=N pi excitations. These excited states may be either localized on a single ketimido unit or may be of the ligand-ligand charge-transfer type. Higher-energy transitions are cyclopentadienyl pi --> CN pi or cyclopentadienyl pi --> phenyl pi in character. The lowest-energy excitation in the (C5Me5)2U[-N=Ph2]2 compound is attributed to f-f and metal-ligand charge-transfer transitions that are not available in the thorium and zirconium analogues. Geometry optimization and vibrational analysis of the lowest-energy triplet state of the zirconium and thorium compounds also aids in the assignment and understanding of the resonance-enhanced Raman data that has recently been reported. [Da Re et al., J. Am. Chem. Soc., 2005, 127, 682.].     

An unusual open cubane structure in a mu(1,1)-azido- and alkoxo-bridged tetranuclear copper(II) complex, [Cu4L2(mu(1,1)-N3)2].5H2O (H3L = N,N'-(2-Hydroxylpropane-1,3-diyl)bis-salicylideneimine)

A new end-on (EO) azido-bridged tetranuclear copper(II) complex [Cu(4)L(2)(mu(1,1)-N(3))(2)].5H(2)O derived from the ligand H(3)L (N,N'-(2-hydroxylpropane-1,3-diyl)bis-salicylideneimine) has been synthesized. Its X-ray structure shows an unusual Cu(4)O(2)N(2) open cubane core in which four copper(II) atoms are connected two by two through two mu(1,1)-azido species and three by three through two alkoxo bridges. The magnetic susceptibility data is dominated by strong antiferromagnetic interactions associated with the alkoxides and weak ferromagnetic interactions arising from the azides, in agreement with magneto-structural correlations found in the literature relative to such bridges in Cu(II) complexes.     

Crystal Structure of 2-pyridine-2-yl-3(pyridine-2-carboxylideneamino)quinazolin-4(3H)-one and its Ligating Diversity Towards Transition Metal(II) Ions

The synthesis of a new ligand 2-pyridine-2-yl-3(pyridine-2-carboxylideneamino)-quinazolin-4(3H)-one (PPCAQ) is described together with its manganese(II), cobalt(II), nickel(II), copper(II), zinc(II) and cadmium(II) complexes. The single crystal X-ray diffraction studies of the ligand reveal the presence of two crystallographically independent molecules in asymmetric unit cell, which exhibit N…N attractive interaction. The PPCAQ and its metal complexes were characterized by analytical, spectroscopic (i.r., n.m.r and u.v.–vis), magnetic moment, conductance and thermal studies. The i.r. spectral studies reveal the ligational diversity of the PPCAQ towards different metal ions as NNN donor in cobalt(II), copper(II), zinc(II) and cadmium(II) complexes and as ONN donor in manganese(II) and nickel(II) complexes. The antimicrobial activity of all the compounds was tested; copper(II), zinc(II) and cadmium(II) complexes show enhanced antibacterial activity compared to the free ligand.     

Crystallographic, electronic, and magnetic studies of zeta(2)-GaM (M = Cr, Mn or Fe): trends in itinerant magnetism

This study of the crystal structure, electronic structure, and magnetic properties of the zeta(2)-GaM (M = Cr, Mn or Fe) alloys is motivated by the recent reinvestigation of the crystallographic Al(8)Cr(5) structure type of zeta(2)-GaMn. The isostructural compounds zeta(2)-GaFe and zeta(2)-GaCr have been refined using X-ray powder diffraction as well as neutron powder diffraction for zeta(2)-GaFe. Their structures have been refined using the space group Rm, with cell parameters a = 12.625(8) A and c = 7.785(10) A for zeta(2)-GaCr and a = 12.4368(11) A and c = 7.7642(10) A for zeta(2)-GaFe. Band structure calculations using the self-consistent, spin-polarized TB-LMTO method were performed to understand their electronic structure and magnetic properties. Band calculations show that from GaCr to GaFe the magnetic interactions change from weakly antiferromagnetic coupling to ferromagnetic coupling. Magnetic measurements confirm ferromagnetism for GaFe and show a weak paramagnetic response for GaCr.     

Geometrical and electronic structures of dinuclear complex ions {(mu-bpym)[Cu(EAr3)2]2}2+ with intramolecular "organic sandwich" formation (E = P or As; Ar = Aryl; bpym = 2,2'-bipyrimidine)

The compound {(mu-bpym)[Cu(AsPh3)2]2}(BF4)2 (1) has been prepared and studied in comparison with the triphenylphosphine analogue 2. Qualitatively, the structure of 1 with characteristically distorted copper(I) coordination caused by Ph/bpym/Ph sandwich interactions is similar to that of 2 and is approximately reproduced by DFT calculations for the model complex ions {(mu-bpym)[Cu(EMe2Ph)2]2}2+, E = P or As. In contrast, the dinuclear {(mu-bpym)[Cu(P(3-Me-C6H4)3)2]2}(BF4)2 (3) displays a distinctly less distorted metal coordination geometry due to the steric requirements of the methyl groups in the meta-tolyl substituents. The electrochemical reduction of 1 is less reversible than for the phosphine analogues; the one-electron-reduced form 1*- exhibits a broad, unresolved EPR signal at g = 2.0023. Resonance Raman spectroscopy of 1 shows the typical vibrations of the bpym ligand in agreement with the MLCT assignment of the long-wavelength transitions below 500 nm. All three dinuclear complexes exhibit luminescence at room temperature in the solid and in solution.     

A novel tetranuclear copper(II) complex with alternating mu 1,1-azido and phenoxo bridges: synthesis,structure, and magnetic properties of [Cu4(mu-salen)2(mu 1,1-N3)2(N3)2

A novel tetranuclear copper(II) complex containing alternating mu(1,1)-azido and monophenoxo bridges has been synthesized and characterized by spectroscopic methods, X-ray single-crystal analysis, and variable-temperature magnetic measurements. The magnetic behavior, investigated in the temperature range 2-300 K, indicates that the interactions between copper ions are antiferromagnetic in nature for both azido and phenoxo bridges. The temperature dependence of the magnetic susceptibility was fitted with J(1) = -12.8 cm(-1), J(2) = -10 cm(-1), g = 2.171, 2.1% paramagnetic component, and negligible temperature-independent paramagnetism (5 x 10(-8)). At variance with the earlier reports of these types of complexes containing a mu(1,1)-azido group, the end-on double-azido-bridged copper(II) center in this complex shows an antiferromagnetic interaction.     

Stereoselective synthesis of (2S,3R)- and (2R,3S)-iodoreboxetine; potential SPECT imaging agents for the noradrenaline transporter

With the aim of developing a new SPECT imaging agent for the noradrenaline transporter, a twelve-step stereoselective synthesis of iodinated analogues of (2S,3R)- and (2R,3S)-reboxetine has been achieved from 4-bromobenzaldehyde. The key steps involve a Sharpless asymmetric epoxidation to establish the stereogenic centres and a copper catalysed aromatic halogen exchange reaction to introduce the key iodine atom. In vitro testing of these compounds using a [(3)H]nisoxetine displacement assay with homogenised rat brain shows both compounds to have significant affinity, with K(i) values of 320.8 nM and 58.2 nM for (2S,3R)- and (2R,3S)-iodoreboxetine respectively.     

Syntheses, structures, and magnetic analyses of a family of heterometallic hexanuclear [Ni4M2] (M = Gd, Dy, Y) compounds: observation of slow magnetic relaxation in the Dy(III) derivative

We described the syntheses, crystal structures, and magnetic behavior of a novel series of heterometallic [Ni(4)M(2)] [M = Gd (1), Dy (2) and Y (3)] hexanuclear compounds afforded by the reaction of rare-earth(III) nitrate, nickel(II) acetate, and Schiff-base ligand 2-(2-hydroxy-3-methoxybenzylideneamino)phenol (H(2)L) in a mixture of ethanol and dichloromethane in the presence of triethylamine. Single-crystal X-ray diffraction measurements reveal that all three compounds have a metal core made up of two Ni(2)MO(4) defective cubanes. The magnetic properties of all compounds have been studied. Solid-state direct-current magnetic susceptibility analyses demonstrate competing antiferromagnetic and ferromagnetic interactions within both compounds 1 and 3. Solid-state alternating-current magnetic susceptibility investigations show a frequency-dependent out-of-phase signal for compound 2 below 4 K, suggestive of slow magnetic relaxation.     

Syntheses, structures, and magnetic properties of diphenoxo-bridged M(II)Ln(III) complexes derived from N,N'-ethylenebis(3-ethoxysalicylaldiimine) (M = Cu or Ni; Ln = Ce-Yb): observation of surprisingly strong exchange interactions

A series of heterodinuclear Cu(II)Ln(III) and Ni(II)Ln(III) complexes, [M(II)L(1)Ln(III)(NO(3))(3)] (M = Cu or Ni; Ln = Ce-Yb), with the hexadentate Schiff base compartmental ligand N,N'-ethylenebis(3-ethoxysalicylaldiimine) (H(2)L(1)) have been synthesized and characterized. The X-ray crystal structure determinations of 13 of these compounds reveal that they are all isostructural. All of these complexes crystallize with the same orthorhombic P2(1)2(1)2(1) space group with closely similar unit cell parameters. Typically, the structure consists of a diphenoxo-bridged 3d-4f dinuclear core, self-assembled to two dimensions due to the intermolecular nitrate...copper(II) or nitrate...nickel(II) semicoordination and weak C-H...O hydrogen bonds. Despite that, the metal centers of the neighboring units are well separated (the ranges of the shortest intermolecular contacts (A) are (M...M) 7.46-7.60, (Ln...Ln) 8.56-8.69, and (M...Ln) 6.12-6.20). Variable-temperature (5-300 K) magnetic susceptibility measurements of all the complexes have been made. The nature of exchange interactions in the Cu(II)Ln(III) systems has been inferred from the Deltachi(M)T versus T plots, where Deltachi(M)T is the difference between the values of chi(M)T for a Cu(II)Ln(III) system and its corresponding Ni(II)Ln(III) analogue. Ferromagnetic interactions seem to be exhibited by the Cu(II)Gd(III), Cu(II)Tb(III), Cu(II)Dy(III), Cu(II)Ho(III), Cu(II)Tm(III), and Cu(II)Yb(III) complexes, while, for the Cu(II)Er(III) complex, no definite conclusion could be reached. On the other hand, among the lower members of the series, the complexes of Ce(III), Nd(III), and Sm(III) exhibit antiferromagnetic interactions, while the Cu(II)Pr(III) and Cu(II)Eu(III) analogues behave as spin-uncorrelated systems. The observations made here vindicate the proposition of Kahn (Inorg. Chem. 1997, 36, 930). The Deltachi(M)T versus T plots also suggest that, for most of the Cu(II)Ln(III) complexes, the exchange interactions are fairly strong, which probably could be related to the small dihedral angle (ca. 4 degrees) between the CuO(2) and LnO(2) planes.     

Structure and magnetic properties of oxychalcogenides A2F2Fe2OQ2 (A = Sr, Ba; Q = S, Se) with Fe2O square planar layers representing an antiferromagnetic checkerboard spin lattice

The oxychalcogenides A2F2Fe2OQ2 (A = Sr, Ba; Q = S, Se), which contain Fe2O square planar layers of the anti-CuO2 type, were predicted using a modular assembly of layered secondary building units and subsequently synthesized. The physical properties of these compounds were characterized using magnetic susceptibility, electrical resistivity, specific heat, (57)Fe Mossbauer, and powder neutron diffraction measurements and also by estimating their exchange interactions on the basis of first-principles density functional theory electronic structure calculations. These compounds are magnetic semiconductors that undergo a long-range antiferromagnetic ordering below 83.6-106.2 K, and their magnetic properties are well-described by a two-dimensional Ising model. The dominant antiferromagnetic spin exchange interaction between S = 2 Fe(2+) ions occurs through corner-sharing Fe-O-Fe bridges. Moreover, the calculated spin exchange interactions show that the A2F2Fe2OQ2 (A = Sr, Ba; Q = S, Se) compounds represent a rare example of a frustrated antiferromagnetic checkerboard lattice.     

Nature of copper(II)-lanthanide(III) magnetic interactions and generation of a large magnetic moment with magnetic anisotropy of 3d-4f cyclic cylindrical tetranuclear complexes [CuIILLnIII(hfac)2]2, (H3L = 1-(2-hydroxybenzamido)-2-(2-hydroxy-3-methoxybenzylideneamino)ethane and Hhfac = hexafluoroacetylacetone,LnIII = Eu,Gd, Tb,Dy)

A cyclic cylindrical 3d-4f tetranuclear structure, in which the 3d and 4f magnetic ions are arrayed alternately, has been found to be a suitable molecular design to produce a large magnetic moment and large magnetic anisotropy. Complexes 3-10 with the chemical formula [MLLn(hfac)2]2 ((MII, LnIII) = (Cu, Eu) (3), (Cu, Gd) (4), (Cu, Tb) (5), (Cu, Dy) (6), (Ni, Eu) (7), (Ni, Gd) (8), (Ni, Tb) (9), (Ni, Dy) (10)) have been synthesized, where H3L = 1-(2-hydroxybenzamido)-2-(2-hydroxy-3-methoxybenzylideneamino)ethane and Hhfac = hexafluoroacetylacetone. The powder X-ray diffractions and FAB-mass spectra demonstrated that these complexes assume a similar tetranuclear structure. The crystal structures of 4 and 5 showed that each complex has a cyclic cylindrical tetranuclear CuII2LnIII2 structure, in which the CuII complex functions as a "bridging ligand-complex" to two adjacent LnIII ions. The temperature-dependent magnetic susceptibilities from 2 to 300 K and the field-dependent magnetizations at 2 K from 0 to 5 T have been measured for four pairs of CuII2LnIII2 and NiII2LnIII2, in which compound NiII2LnIII2 containing diamagnetic NiII ion was used as the reference complex to evaluate the CuII-LnIII magnetic interaction. Comparison of the magnetic properties of the CuII2LnIII2 complex with those of the corresponding NiII2LnIII2 complex showed that the magnetic interaction between CuII and EuIII ions is weakly ferromagnetic and that between CuII and either of GdIII, TbIII, and DyIII ions is ferromagnetic. Complex CuII2GdIII2, 4, has an S = 8 spin ground state, due to the ferromagnetic spin coupling between SGd = 7/2 and SCu = 1/2 with coupling constants of J1 = +3.1 cm-1 and J2 = +1.2 cm-1. The magnetic measurements showed that compounds 5 and 6, CuII2LnIII2 (LnIII = Tb, Dy), exhibit large magnetic moments and large magnetic anisotropy due to the LnIII ion.     

Module-based assembly of copper(II) chloranilate compounds: syntheses, crystal structures, and magnetic properties of [[Cu(2)(CA)(terpy)(2)][Cu(CA)(2)]](n)() and [[Cu(2)(CA)(terpy)(2)(dmso)(2)][Cu(CA)(2)(dmso)(2)](EtOH)](n)(H(2)CA = chloranilic acid, terpy = 2,2':6',2' '-terpyridine, dmso = dimethyl sulfoxide)

Two new copper(II) compounds of chloranilate and 2,2':6',2' '-terpyridine have been synthesized, and the structures have been solved by the single-crystal X-ray diffraction method. The crystal structure of [[Cu(2)(CA)(terpy)(2)][Cu(CA)(2)]](n)(1), where H(2)CA = chloranilic acid and terpy = 2,2':6',2' '-terpyridine, consists of two modules, the dimer unit [Cu(2)(CA)(terpy)(2)](2+) and the anionic mononuclear unit [Cu(CA)(2)](2)(-), forming an alternated chain. The chain is stabilized by semicoordinating and additional but efficient secondary bonding interactions. The crystal structure of [[Cu(2)(CA)(terpy)(2)(dmso)(2)][Cu(CA)(2)(dmso)(2)](EtOH)](n)(2), where dmso = dimethyl sulfoxide, consists of solvent molecules and two discrete modules, the dimer unit [Cu(2)(CA)(terpy)(2)(dmso)(2)](2+) and the anionic mononuclear unit [Cu(CA)(2)(dmso)(2)](2)(-). The dimer units form a layer by secondary bonding interactions, and the monomer units and ethanol molecules are introduced between the layers. The magnetic properties of 1 and 2 have been investigated in the temperature range 2.0-300 K. A weak ferromagnetic interaction was observed in 1, J(a) = 2.36 cm(-)(1) and zJ(b) = -0.68 cm(-)(1) while no exchange coupling was observed in 2.     

Parametrization of the magnetic behavior of the triangular spin ladder chains organically templated: (C2N2H10)[M(HPO3)F3] (M(III) = Fe, Cr, and V). Crystal structure and thermal and spectroscopic properties of the iron(III) phase

A new iron(III) phosphite templated by ethylenediamine has been synthesized using solvothermal conditions under autogenous pressure. The (C2N2H10)[Fe(HPO3)F3] compound has been characterized by single-crystal X-ray diffraction data and spectroscopic and magnetic techniques. The crystal structure is formed by chains extended along the c axis and surrounded by ethylenediammonium cations. A study by diffuse-reflectance spectroscopy has been performed, and the calculated Dq, B, and C parameters for the Fe(III) cations are 1030, 720, and 3080 cm(-1), respectively. The M?ssbauer spectrum at room temperature is characteristic of Fe(III) ions. The electron spin resonance (ESR) spectra carried out at different temperatures show isotropic signals with a g value of 2.00(1). The thermal evolution of the intensity of the ESR signals indicates the existence of antiferromagnetic interactions for the Fe(III) phase. The magnetic susceptibility data of the Cr(III) and V(III) compounds show antiferromagnetic couplings. The J-exchange parameters of the Fe(III) and Cr(III) compounds have been calculated by using a model for a triangular spin ladder chain. The values are J1 = -1.63(1) K and J2 = -0.87(2) K with g = 2.02 for the Fe(III) phase and J(1) = -0.56(2) K and J2 = -0.40(2) K with g = 1.99 for the Cr(III) compound. In the case of the V(III) phase, the fit has been performed considering a linear chain with the magnetic parameters D = 2.5 cm(-1) and J = -1.15(1) K.     

Dinuclear cobalt(II) and copper(II) complexes with a Py2N4S2 macrocyclic ligand

The interaction between Co(II) and Cu(II) ions with a Py(2)N(4)S(2)-coordinating octadentate macrocyclic ligand (L) to afford dinuclear compounds has been investigated. The complexes were characterized by microanalysis, conductivity measurements, IR spectroscopy and liquid secondary ion mass spectrometry. The crystal structure of the compounds [H(4)L](NO(3))(4), [Cu(2)LCl(2)](NO(3))(2) (5), [Cu(2)L(NO(3))(2)](NO(3))(2) (6), and [Cu(2)L(μ-OH)](ClO(4))(3)·H(2)O (7) was also determined by single-crystal X-ray diffraction. The [H(4)L](4+) cation crystal structure presents two different conformations, planar and step, with intermolecular face-to-face π,π-stacking interactions between the pyridinic rings. Complexes 5 and 6 show the metal ions in a slightly distorted square-pyramidal coordination geometry. In the case of complex 7, the crystal structure presents the two metal ions joined by a μ-hydroxo bridge and the Cu(II) centers in a slightly distorted square plane or a tetragonally distorted octahedral geometry, taking into account weak interactions in axial positions. Electron paramagnetic resonance spectroscopy is in accordance with the dinuclear nature of the complexes, with an octahedral environment for the cobalt(II) compounds and square-pyramidal or tetragonally elongated octahedral geometries for the copper(II) compounds. The magnetic behavior is consistent with the existence of antiferromagnetic interactions between the ions for cobalt(II) and copper(II) complexes, while for the Co(II) ones, this behavior could also be explained by spin-orbit coupling.     

Electronic structure and normal vibrations of CH3(OCH2CH2)nOCH3-M+-CF3SO3- (n = 2-4, M = Li, Na, and K)

Electronic structure and the vibrational frequencies of CH(3)(OCH(2)CH(2))(n)OCH(3)-M(+)-CF(3)SO(3)(-) (n = 2-4, M = Li, Na, and K) complexes have been derived from ab initio Hartree-Fock calculations. The metal ion shows varying coordination from 5 to 7 in these complexes. In tetraglyme-lithium triflate, Li(+) binds to one of the oxygens of CF(3)SO(3)(-) (triflate or Tf(-)) unlike for potassium or sodium ions, which possess bidentate coordination. Structures of glyme-MTf complexes thus derived agree well with those determined from X-ray diffraction experiments. The metal ion binds more strongly to ether oxygens of tetraglyme than its di- or triglyme analogues and engenders contraction of SO (for oxygens binding to metal ion) bonds with consequent frequency upshift for the corresponding vibration in the complex relative to those in the free MTf ion pairs. Complexation of the diglyme with LiTf engenders the largest downshift (91 cm(-1)) for the SO(2) stretching vibration of the free anion, which suggests stronger binding of lithium to the diglyme than the tri- (79 cm(-1)) or tetraglyme (70 cm(-1)). A frequency shift in the opposite direction for the SO (where oxygens do not coordinate to the metal) and CF(3) stretchings, which stems from the ion-polymer and anion-ion interactions, has been noticed. These frequency shifts have been analyzed using natural bond orbital analysis and difference electron density maps coupled with molecular electron density topography.     

Synthesis and characterization of novel dinuclear copper(I) complexes. Dimerization of [CuL(PPh3)2] (L = methyl 3-hydroxy-3-(p-R-phenyl)-2-propenedithioate)

We report the synthesis of new copper(I) complexes 6a-e from methyl 3-hydroxy-3-(p-R-phenyl)-2-propenedithioate ligands. These complexes were characterized by IR and 1H, 13C, and 31P NMR spectroscopy. The expected O,S-coordination mode was confirmed by the X-ray diffraction studies of 6b and 6e. The unexpected dimerization of 6b-e leads to the formation of four novel dinuclear copper(I) compounds (7b-e). The dinuclear complex structure was fully established by the X-ray diffraction analysis of 7a, in which the presence of a Cu-Cu interaction was observed.