nan Effendy

Crystal structures and spectroscopic studies of the mononuclear complex [AgBr(PPh3)2] and binuclear [Ag2X2(PPh3)4]·2CHCl3(X = Cl or Br)

The structure of the silver(I) complexes [AgBr(PPh3)2] and [Ag2X2(PPh3)4]·2CHCl3(X = Cl or Br) have been determined by single-crystal X-ray diffraction. The complex [AgBr(PPh3)2] crystallizes in the monoclinic space group C2/c and contains discrete monomeric [AgBr(PPh3)2] units with essentially trigonal-planar AgBrP2 co-ordination, and a crystallographic two-fold axis of symmetry coincident with the Ag–Br bond. The geometric parameters for the silver atom environment are: Ag–Br 2.568(1), Ag–P 2.458(2)A, P–M–P 124.14(5), P–M–Br 117.93(3)°. The complexes [Ag2X2(PPh3)4]·2CHCl3(X = Cl or Br) are isomorphous, monoclinic, space group C2/c, and contain [Ag2X2(PPh3)4] dimers. Each of the two silver atoms in the structure is four-co-ordinated by forming bonds with the P atoms of the two phosphine ligands and the two doubly bridging halide atoms. The Ag and X atoms lie in a plane, and each of the molecules in the unit cell has a C2 axis which passes through the two X atoms. A chloroform molecule is hydrogen bonded to each X atom. The far-IR spectra of these complexes show bands which are assigned to ν(AgX) modes, and the spectra of these and the unsolvated dimer [Ag2Cl2(PPh3)4] are analysed to yield information about the Ag–X bonding. The Raman spectrum of [AgBr(PPh3)2] shows a band which is assigned to a ν(AgP) mode, an assignement which is confirmed by the observation of similar bands in the Raman spectra of the isostructural gold(I) complexes [AuX(PPh3)2](X = Cl, Br or I). The solid-state cross-polarization magic-angle spinning (CP MAS)31P NMR spectra of the silver complexes show multiplets die to 1J(AgP) coupling. The spectra of the dimers show separate chemical shifts for the crystallographically inequivalent phosphorus atoms, and 2J(PP) coupling between these atoms. The splitting patterns are interpreted in terms of the silver co-ordination environment.

Synthesis, characterization and X-ray structural studies of novel dinuclear silver(I) complexes of poly(azolyl)borate ligands

Abstract A series of Ag(I) complexes of tris- and tetrakis-(pyrazolyl)hydroborates, tetrakis(imidazol-1-yl)borate, and hydrotris(3-methyl-1-imidazolyl-2-thione)borate, namely the previously recorded [Ag{HB(pz) 3 }] 2 , [Ag{HB(3,5-Me 2 pz) 3 }] 2 , [Ag{B(pz) 4 }] n , together with [Ag{HB(4-Brpz) 3 }] 2 , [Ag{B(3-Mepz) 4 }] n , [Ag{B(im) 4 }] n (Him=imidazole) and [Ag{Tm}] 2 (Tm=hydrotris(3-methyl-2-thioxo-1-imidazolyl)borate) have been synthesized and further characterized by elemental analysis, IR, Far–IR, 1 H, 13 C NMR spectroscopy, and in the case of [Ag{Tm}] 2 , also by a single-crystal X-ray study. Variable-temperature 1 H NMR spectra indicate that [Ag{HB(3,5-Me 2 pz) 3 }] 2 , [Ag{HB(4-Brpz) 3 }] 2 , and [Ag{B(pz) 4 }] n are fluxional, with a pyrazolyl ring exchange process occurring rapidly at 293 but not at 193 K, whereas [Ag{HB(pz) 3 }] 2 and the crystalline form of [Ag{HB(3,5-Me 2 pz) 3 }] 2 are not fluxional, even at room temperature. The reactions between K[HB(pz) 3 ], K[HB(3,5-Me 2 pz) 3 ], K[B(pz) 4 ] or K[Tm] and AgNO 3 in presence of N -and S -donor, unidentate or bidentate ligands such as pyrazole, imidazole, 1-10-phenanthroline and 1-methylimidazoline(2,3 H )thione (Hmimt) were investigated. We also report the results of positive ion FAB MS studies carried out for selected derivatives.

Silver(I) derivatives with new functionalised acylpyrazolonates

Abstract Silver(I) acylpyrazolonate derivatives of formula [Ag(Q)(R 3 P)] 2 and [Ag(Q)(R 3 P) 2 ], (QH=1-phenyl-3-methyl-4-R′(Cue605O)-pyrazol-5-one; Q O H, R′=furane; Q S H, R′=thiophene; R=Ph, Cy, o -tol), have been synthesised and characterised, both in the solid state and in solution. The derivatives [Ag(Q)(R 3 P)] 2 contain dinuclear AgO 2 NP units with the acylpyrazolonate coordinating in a bridging O , O ′-Q- N fashion. The [Ag(Q)(R 3 P) 2 ] are tetrahedral species, with the distortion from ideal geometry increasing with the bulk of the phosphine. The [Ag(Q)(R 3 P) 2 ] derivatives are fluxional in chloroform solution when R 3 P is sterically hindered (R=Cy or o -tol), dissociating partially to the [Ag(Q)(R 3 P)] fragment and free R 3 P. [Ag(Q S )(Ph 3 P)] 2 reacts with 1-methyl-2-mercaptoimidazole (Hmimt) affording the compound [Ag(Hmimt)(Ph 3 P)(Q S )] and [Ag(Q O )(Ph 3 P)] 2 reacts with 1-methyl-imidazole (Meim) affording the compound [Ag(Meim)(Ph 3 P)(Q O )], whereas [Ag(Q S )(Ph 3 P)] 2 reacts with 1,10-phenanthroline (phen), affording the compound [Ag(phen)(Ph 3 P)](Q S ). Finally [Ag(Q S )(Ph 3 P) 2 ] reacts with phen producing the ionic species [Ag(phen)(Ph 3 P) 2 ](Q S ).

Solution and mechanochemical syntheses, and spectroscopic and structural studies in the silver(I) (bi-)carbonate: triphenylphosphine system.

Syntheses of a number of adducts of silver(I) (bi-)carbonate with triphenylphosphine, both mechanochemically, and from solution, are described, together with their infra-red spectra, (31)P CP MAS NMR and crystal structures. Ag(HCO(3)):PPh(3) (1:4) has been isolated in the ionic form [Ag(PPh(3))(4)](HCO(3))·2EtOH·3H(2)O. Ag(2)CO(3):PPh(3) (1:4) forms a binuclear neutral molecule [(Ph(3)P)(2)Ag(O,μ-O·CO)Ag(PPh(3))(2)](·2H(2)O), while Ag(HCO(3)):PPh(3) (1:2) has been isolated in both mononuclear and binuclear forms: [(Ph(3)P)(2)Ag(O(2)COH)] and [(Ph(3)P)(2)Ag(μ-O·CO·OH)(2)Ag(PPh(3))(2)] (both unsolvated). A more convenient method for the preparation of the previously reported copper(I) complex [(Ph(3)P)(2)Cu(HCO(3))] is also reported.

Silver derivatives of tris(pyrazol-1-yl)methanes. A silver(I) nitrate complex containing a tris(pyrazolyl)methane coordinated in a bridging mode

Abstract The reaction of AgX (X=ClO4, NO3 or SO3CH3) acceptors with excesses of tris(pyrazol-1-yl)methane ligands L (L=CH(pz)3, CH(4-Mepz)3, CH(3,5-Me2pz)3, CH(3,4,5-Me3pz)3 or CH(3-Mepz)2(5-Mepz)) yields 1:1 [AgX(L)], 2:1 [Ag(L)2]X or 3:2 [(AgX)2(L)3] complexes. The ligand to metal ratio in all complexes is dependent on the number and disposition of the Me substituents on the azole ring of the neutral ligand and on the nature of the Ag(I) acceptor. All complexes have been characterized in the solid state as well as in solution (medium- and far-IR, 1H and 13C NMR and conductivity determinations) and the solid-state structures of [Ag(NO3){(pz)3CH}](∞/∞) and [Ag{(3,5-Me2pz)3CH}2]NO3 determined by single crystal X-ray studies.

Oligo-nuclear silver thiocyanate complexes with monodentate tertiary phosphine ligands, including novel ‘cubane’ and ‘step’ tetramer forms of AgSCN : PR3 (1 : 1)4

Adducts of a number of tertiary pnicogen ligands ER(3) (triphenyl-phosphine and -arsine (PPh(3),AsPh(3)), diphenyl,2-pyridylphosphine (PPh(2)py), tris(4-fluorophenyl)phosphine (P(C(6)H(4)-4F)(3)), tris(2-tolyl)phosphine (P(o-tol)(3)), tris(cyclohexyl)phosphine (PCy(3))), with silver(I) thiocyanate, AgSCN are structurally and spectroscopically characterized. The 1:3 AgSCNu2009:u2009ER(3) complexes structurally defined (for PPh(3),AsPh(3) (diversely solvated)) take the form [(R(3)E)(3)AgX], the thiocyanate X = NCS being N-bound, thus [(Ph(3)E)Ag(NCS)]. A 1:2 complex with PPh(2)py, takes the binuclear form [(pyPh(2)P)(2)Ag()Ag(PPh(2)py)(2)] with an eight-membered cyclic core. 1:1 complexes are defined with PPh(2)py, P(o-tol)(3) and PCy(3); binuclear forms [(R(3)P)Ag()Ag(PR(3))] are obtained with P(o-tol)(3) (two polymorphs), while novel isomeric tetranuclear forms, which may be envisaged as dimers of dimers, are obtained with PPh(2)py, and, as further polymorphs, with PCy(3); these latter may be considered as extensions of the cubane and step forms previously described for [(R(3)E)AgX](4) (X = halide) complexes. Solvent-assisted mechanochemical or solvent-assisted solid-state synthesis methods were employed in some cases, where complexes could not be obtained by conventional solution methods, or where such methods yielded a mixture of polymorphs unsuitable for solid-state spectroscopy. The wavenumbers of the ν(CN) bands in the IR spectra are in broad agreement with the empirical rule that distinguishes bridging from terminal bonding, but exceptions occur for compounds that have a double SCN bridged dimeric structure, and replacement of PPh(3) with PPh(2)py apparently causes a significant decrease in ν(CN) to well below the range expected for bridging SCN in these structures. (31)P CP MAS NMR spectra yield additional parameters that allow a correlation between the structures and spectra.

Solution and solid-state structural properties of silver(I) poly(pyrazolyl)borate compounds with bidentate diphosphines

Abstract New silver(I) derivatives containing bidentate tertiary phosphines and anionic poly(pyrazol-1-yl)borates have been prepared from AgNO3 and bis(diphenylphosphino)methane (dppm), 1,2-bis(diphenylphosphino)ethane (dppe), 1,3-bis(diphenylphosphino)propane (dppp), 1,4-bis(diphenylphosphino)butane (dppb) or 1,1′-bis(diphenylphosphino)ferrocene (dppf) and K[H2B(pz)2], K[H2B(3,5-Me2pz)2], K[B(pz)4] or K[B(3-Mepz)4] (pzH=pyrazole); their solid state and solution properties have been investigated through analytical and spectroscopic measurements (IR, 1H and 31P NMR). The 1H and 31P NMR spectra have been interpreted with equilibria that involve mono- and di-nuclear complexes, or the presence of 1:1 and 1:2 silver-diphosphine species. The compounds are soluble in chlorinated solvents and are non-electrolytes in CH2Cl2 and acetone solutions. The structures of [(dppf){Ag(pz)2BX2}], X=H, pz have been determined by single crystal X-ray studies, the poly(pyrazolyl)borates being always bidentate with the silver(I) centers in distorted tetrahedral geometries.

Spectroscopic and structural studies on 1 : 2 adducts of silver(I) salts with tricyclohexylphosphine

Adducts of a number of silver(I) salts, AgX, with tricyclohexylarsine, of 1∶1 AgX∶As(C6H11)3 stoichiometry have been synthesized for Xxa0=xa0Cl, Br, I, NO3, NCO or CN and subjected to room temperature single crystal X-ray determinations and studies of their low frequency vibrational spectra. The chloride is binuclear [{(C6H11)3As}Ag(µ-Cl)2Ag{As(C6H11)3}], isomorphous with its previously recorded P(C6H11)3, Xxa0=xa0Cl, Br counterparts, the silver environment being quasi-planar, trigonal AsAg(µ-Cl)2; the nitrate is isomorphous, with a central planar Ag(µ-O)2Ag array, a pair of oxygen atoms, one from each of a pair of symmetry-related nitrate groups, bridging the two silver atoms. The present bromide, unlike its P(C6H11)3 counterpart, is not a dimer, but, like the iodide, a ‘cubane’ tetramer; the iodide is isomorphous with its P(C6H11)3 analogue, a crystallographic 2 axis passing through a pair of opposed faces of the tetramer, but the bromide is of a new type, rhombohedral space group R. Remarkably, the cyanate is also of the cubane form, the first recorded (other than an organometallic) incorporating a first-row atom, obtained unsolvated and bis(pyridine) solvated. The cyanide is a linear polymer .xa0.xa0. {(C6H11)3As}2AgNCAgCN{As(C6H11)3}2AgNC .xa0.xa0. (‘α’ phase, from 2-methylpyridine); a second ‘β’ phase was obtained from 2,4,6-trimethylpyridine, of similar form, while from pyridine, a solvate of 3∶4∶2 AgCN∶As(C6H11)3∶py stoichiometry [{Ag[As(C6H11)3]2(py)}2(CN)][Ag(CN)2] was obtained. The structure of the Exa0=xa0Pxxa0=xa0CN unsolvated 1∶1 analogue was also determined, also being a linear polymeric array like its Exa0=xa0As counterpart. The far-IR spectra of the halide complexes exhibit bands due to ν(AgX) vibrational modes at 229, 148 cm–1 (Xxa0=xa0Cl), 167, 151, 125, 109 cm–1 (Xxa0=xa0Br) and at 111, 86 cm–1 (Xxa0=xa0I). These spectra were interpreted in terms of idealised C2h Ag2Cl2 and Td Ag4X4 structures of the silver halide cores.

Metal ion recognition. Interaction of new oxygen-nitrogen donor macrocycles with selected transition and post-transition metal ions

As part of an ongoing investigation of the factors influencing metal ionrecognition, we have investigated structure/function relationships involvingthe metal-ion binding by three new N-benzyl-substituted, 15- and 16-membered,macrocyclic ligands incorporating N2O 3- and N 3O 3-donor sets (withthe N 3O 3-system consisting of a N 2O 3-macrocyclic ring with an attachedCH 2CH 2NCH 2C 6H 5 pendant arm). Selected solid complexes of thelatter ligand were isolated and the X-ray structures of individual Ni(II) and Ag(I) complexeswere obtained.Where solubility permitted, potentiometric titration studies in 95% methanolwere employed to investigate the binding affinities of all three ligand derivativestowards Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Ag(I) and Pb(II). The 15-memberedN 2O 3-ring was found to be selective for Ag(I) over the other six metalsinvestigated, including Cu(II). However, the presence of a further nitrogen donorin the form of the pendant benzylamine functionality in the N 3O 3-donorsystem results in an increase in its binding affinity for Ag(I) but an even greaterincrease occurs for Cu(II). As a consequence, the latter ion is now more stronglybound than Ag(I). The factors influencing these respective selectivities are discussed.

True and quasi-isomorphism in tetrakis(acetonitrile)coinage metal(I) salts

Salts of the family [M(NCMe)4]+X− (M = Cu, Ag; X− = [BF4]−, [ClO4]−, [PF6]− crystallize in the space groups Pna21 or P212121 with very similar cell dimensions. This gives rise to two sets of true isomorphs (four members in Pna21, two in P212121), and a solvated species (Cu/PF6/MeCN) with a distorted P212121 lattice. Across the two space groups and regardless of the choice of metal atom or anion, the underlying basic structures are virtually identical in the six unsolvated cases, consisting of alternate sheets of cations and anions, mainly held together by C–H⋯C,N and C,N⋯C,N interactions, and a columnar cation–anion motif perpendicular to the sheets maintained by C–H⋯F,O interactions. The pair of concomitant polymorphs found with Cu/BF4 in both Pna21 and P212121 can readily be described as being quasi-isomorphous. Using a Hirshfeld surface approach and a tri-cationic structural synthon extracted from the asymmetric units, the common underlying pattern of close intercomponent approaches has been analysed and quantified. The structure of the Ag/PF6 complex is new; low-temperature redeterminations are recorded for the Ag/ClO4 and the Cu/PF6/MeCN complexes.