Syntheses, structures and vibrational spectroscopy of some 1:2 and 1:3 adducts of silver(I) oxyanion salts with pyridine and piperidine bases containing non-coordinating 2(,6)-substituents

Synthetic, single crystal X-ray structural characterizations and vibrational spectroscopic studies are recorded for a number of adducts of 1:2 stoichiometry of silver(I) oxyanion salts for oxyanions of differing basicity (perchlorate, nitrate, carboxylate (as trifluoroacetate (≡‘tfa’))), with a variety of pyridine (≡‘py’) or piperidine (≡‘pip’) bases hindered in the 2- (and, sometimes, 6-) position(s) by methyl or non-coordinating functionalities of other types, the ligands employed being 2-methylpyridine (‘2mp’), 2,6-dimethylpyridine (‘lut’), 2,4,6-trimethylpyridine (‘coll’), quinoline (‘quin’), 2,2,6,6-tetramethylpiperidine (‘tmp’), 2-amino-,6-methylpyridine (‘nmp’), 2-methoxypyridine (‘mop’) and 2-cyanomethylpyridine (‘pcn’); studies are also recorded of adducts with the parent, ‘py’, base and with 4-cyanopyridine (‘cnp’). In the majority of the complexes, the NAgN motif predominates, as might be expected, variously distorted from linearity in response to changes in (competing) basicities of the nitrogen base and any nearby anion or solvent molecule; an unusual variation is found in the highly hindered tmp/tfa adduct which is a monohydrate with interacting water displacing the rather basic anion, the converse being the case in the corresponding nitrate, also a monohydrate. With the less-hindered base mpy, both nitrate and trifluoroacetate are binuclear, with O and OCO bridges corresponding to centrosymmetric four- and eight-membered rings, respectively; the quin/nitrate adduct is more complex, also binuclear but with bis(chelating) nitrate. AgNO₃:py (1:3) is found to be binuclear, while with Agtfa/py, a 3:2 adduct [Ag(py)₂][Ag₂(tfa)₃]_(∞|∞) is found with a novel, polymeric, strongly interacting anion. A further pair of 1:3 adducts, AgNO₃:2np (2np = 2-aminopyridine) and Agtfa:nmp, both mononuclear [AgL₃]⁺X⁻ are described, differing in the modes of interaction of silver with the three N-bases. In all simple NAgN systems with aromatic ligands, the pair of ligand ‘planes’ is disposed quasi-parallel.The far-IR spectra of [AgL₂]Y (L = lut, coll; Y = ClO₄, NO₃, tfa) and of [Ag(py)_n](ClO₄) (n = 2,4) have been recorded and the ν(AgN) bands assigned in the range 80-240 cm⁻¹. For the L = lut, coll complexes, there is a clear trend of decreasing ν(AgN) following increasing r(AgN) as the interaction with the counterion increases along the series Y = ClO₄, NO₃, tfa.     

Structural aspects of some 2:1 dipyridylamine complexes of some copper(II) salts: An interesting new polymorph of the binuclear carbonate/perchlorate tetrahydrate adduct

Recent work has described the structural characterization of the complexes :dpyam:H₂O (1:4:4), X′ = ClO₄, BF₄, ‘dpyam’ = dipyridylamine, as a pair of triclinic Z = 1 isomorphs, the cations being modelled in terms of pairs of copper atoms bridged by a carbonate ion disordered about a crystallographic inversion centre. This work has been revisited in the course of describing a new polymorph of the perchlorate in a triclinic cell of twice the size, in which the carbonate unit, now non-disordered, bridges a pair of crystallographically independent copper atoms which display distinctly different coordination environments, one close to the square-pyramidal norm, the other not. Studies of adducts of the form [(dpyam)₂CuX]X′(·nH₂O) are also recorded. The X/X′ = propionate/iodide adduct is found to be isomorphous with its acetate/BF₄ but, interestingly, not its propionate/Cl counterpart. ‘Low’-temperature redeterminations of the NCO/Cl · 4H₂O and nitrite/ClO₄ adducts are also recorded, enabling definition of the hydrogen-bonding scheme in the former.     

The structural definition of adducts of stoichiometry MX:dpex (2:3)(∞), M = Cu, Ag, X = simple anion, dpex = Ph2E(CH2)xEPh2, E = P, As

Single crystal X-ray structural characterizations are recorded for a number of adducts of MX:dpex (2:3) stoichiometry (MX = simple univalent copper or silver salt; dpex = Ph₂E(CH₂)_xEPh₂ (E = P, As)). CuX:dppe (2:3) (X = Cl, Br, I, CN) are binuclear [(dppe-P,P′)CuX(P-dppe-P′)CuX(P,P′-dppe)], all centrosymmetric. AgX:dpex (2:3) (dpex = ‘dpae’ (Ph₂As(CH₂)₂AsPh₂), X = Br, F₃CCO₂ (= ‘tfa’), F₃CSO₃ (≡ ‘tfs’); dpex = ‘dpape’ (Ph₂As(CH₂)₂PPh₂), X = CN, SCN, OClO₃) are one-dimensional polymers ?-E′)₁AgX(E-dpex-E′)₂-AgX(E-dpex-E′)₁AgX?, P, As sites scrambled in the latter. AgNO₃:dpam (2:3) is also a one-dimensional polymer, ?AgO·NO·OAg(As-dpam-As)AgO·NO·OAg? (‘dpam’ ≡ Ph₂As(CH₂)₂AsPh₂). AgX:dpae (2:3) (X = I, CN, ClO₄, NO₃) and AgX:dpape (2:3) (X = Br, I, NO₃) are two-dimensional polymers with large 30-membered macrocyclic rings; similar webs are found for dppx ligands in AgOH:dppb (2:3) and AgNCO, Agtfa:dpph (2:3) with 42- and 54-membered rings. Complexes AgX:dpape (1:3) (X = Cl, Br) are defined as mono-nuclear [XAg(Ph₂P(CH₂)₂AsPh₂)₃] arrays, the unidentate ligands predominantly P-bound. Synthetic procedures for the adducts are reported, selected compounds being characterized both in solution (¹H, ³¹P NMR, ESI MS) and in the solid state (IR).     

Synthesis and structural characterization of adducts of silver(I) carboxylate salts AgX (X = CF3COO, CH3COO) with ER3 (E = P, As; R = Ph, cy, o-tolyl) and oligodentate aromatic bases derivative of 2,2′-bipyridyl, L, AgX:PR3:L (1:1:1)

Twenty-one adducts of the form AgX:ER₃:L (1:1:1) (X = CF₃COO (‘tfa’), CH₃COO (‘ac’), E = P, As; R = Ph, cy, o-tolyl; L = 2,2′-bipyridyl (‘bpy’)-based ligand) have been synthesized and characterized by analytical, spectroscopic (IR, far-IR, ¹H, ¹⁹F and ³¹P NMR) and single crystal X-ray diffraction studies. The resulting complexes are predominantly of the form [(R₃E)AgL]⁺X⁻, with a trigonal EAgN₂ coordination environment, the planarity of which may be perturbed by the approach of anion or solvent. The carboxylate anions have been found to be uni-, or semi-bidentate, or also completely ionic, as in the complexes [Ag(PPh₃)(bpy)(H₂O)](tfa) and [Ag(PPh₃)(dpk · H₂O)](tfa) (‘dpk · H₂O’ = bis(2-pyridyl)ketone (hydrated)). The complexes Agac:PPh₃:dpa (1:1:1) and Agac:P(o-tol)₃:dpa:MeCN (1:1:1:1) are dinuclear, with bridging unidentate acetate and terminal unidentate dpa (‘dpa’ = bis(2-pyridyl)amine).     

Syntheses and structures of adducts of stoichiometry MX:dpex (2:1)(n), M = Cu, Ag, X = (pseudo-) halogen, dppx = Ph2E(CH2)xEPh2, E = P, As

Single crystal X-ray studies have defined the structures of a number of adducts of the form MX:dpex (2:1), M = univalent coinage metal (Cu, Ag), X = (pseudo-)halide, dpex = bis(diphenylpnicogeno)alkane, Ph₂E(CH₂)_xEPh₂, E = P, As, of diverse types, some novel. The adducts of AgCl,Br:dppm and AgNCO:dpem (x = 1) are tetranuclear as is the AgNO₃:dppp (x = 3) array, all derivative of the familiar ‘step’ structure while the combination CuCN:dppm yields a two-dimensional web of twenty-membered macro/metallacycles. Synthetic procedures for all adducts have been reported. All compounds have been characterized both in solution (¹H, ¹³C, ³¹P NMR, ESI MS) and in the solid state (IR).     

Structural characterizations of some adducts of silver(I) nitrate and perchlorate with some cyclic di- (or tri-) ene organic ligands

Single crystal X-ray structural characterizations of some adducts of silver(I) nitrate and perchlorate with assorted organic poly-ene ligands (nbd = norbornadiene, bicyclo[2.2.1]hepta-2,5-diene; cod = 1,5-cyclooctadiene; cdt ≡ trans,trans,cis-cyclododeca-1,5,9-triene) are reported, all being polymeric in form (with the exception of mononuclear ionic AgClO₄:cod (1:2)), with chains comprised of alternating silver and nitrate/perchlorate components substituted or linked by unsaturated donors which complete the coordination spheres of the silver atoms. In AgNO₃:nbd (2:1) (a redetermination), pairs of silver/nitrate strands are linked in a one-dimensional polymer by the nbd ligands. In AgNO₃:nbd (1:1)_∞, meandering silver/nitrate strands containing pairs of independent silver and nitrate units in a crystallographic mirror plane are linked to either side with parallel planes by nbd ligands. In AgNO₃:cod (1:1)_∞, the cod ligands ‘chelate’ to the silver atoms in a silver/nitrate chain. In AgNO₃:cdt (1:2)_∞, pairs of ‘unidentate’ cdt ligands are pendant from a silver/nitrate chain, while in the (1:1)_∞ adduct, the cdt ligands bridge pairs of silver atoms from an adjacent chain forming a two-dimensional web. A common form of the bridging nitrate group in the above is as an O,O′-NO₃-O′,O″ bis-chelate, the pair of the bis-oxygen chelates having a common oxygen atom.     

Synthesis and structural characterization of adducts of silver(I) perchlorate with PR3 (R = Ph, cy, o-tolyl) and oligodentate aromatic bases derivative of 2,2′-bipyridyl, L, AgClO4:PR3:L (1:1:1)

Ten novel adducts of the form AgClO₄:PR₃:L (1:1:1) (R = Ph, cy, o-tolyl; L = 2,2′-bipyridyl (‘bpy’), 2,2′-biquinoline (‘bq’), bis(2-pyridyl)amine (‘dpa’), bis(2-picolyl)amine (‘dpca’)) have been synthesized and characterized by analytical, spectroscopic (IR, far-IR, ¹H and ³¹P NMR) and single crystal X-ray diffraction studies. The solid state molecular structures show that the complexes predominantly take the form [(R₃P)AgL]⁺X⁻, with a trigonal PAgN₂ coordination environment, where the approach of the anion or the solvent may perturb the planarity of the silver environment. The ClO₄ anion shows uni- or semi-bidentate coordination, except in the complexes AgClO₄:PR₃:dpca (1:1:1) (R = Ph and o-tolyl), where the anion remains uncoordinated and the dpca donor is a three-coordinate pincer-like ligand.     

Syntheses, structures and vibrational spectroscopy of some unusual silver(I) (pseudo-) halide/unidentate nitrogen base polymers

The meagre (structurally defined) array of 1:2 silver(I) (pseudo-)halide:unidentate nitrogen base adducts is augmented by the single-crystal X-ray structural characterization of the 1:2 silver(I) thiocyanate:piperidine (‘pip’) adduct. It is of the one-dimensional ‘castellated polymer’ type previously recorded for the chloride: ?Ag(pip)₂(μ-SCN)Ag(pip)₂? a single bridging atom (S) linking successive silver atoms. By contrast, in its copper(I) counterpart, also a one-dimensional polymer, the thiocyanate bridges as end-bound SN-ambidentate: ?CuSCNCuSCN? A study of the 1:1 silver(I) bromide:quinoline (‘quin’) adduct is recorded, as the 0.25 quin solvate, isomorphous with its previous reported ‘saddle polymer’ chloride counterpart.Recrystallization of 1:1 silver(I) iodide:tris(2,4,6-trimethoxyphenyl)phosphine (‘tmpp’) mixtures from py and quinoline (‘quin’)/acetonitrile solutions has yielded crystalline materials which have also been characterized by X-ray studies. In both cases the products are salts, the cation in each being the linearly coordinated silver(I) species [Ag(tmpp)₂]⁺, while the anions are, respectively, the discrete [Ag₅I₇(py)₂]²⁻ species, based on the already known but unsolvated [Cu₅I₇]²⁻ discrete, and the polymeric, arrays, and polymeric . The detailed stereochemistry of the [Ag(tmpp)₂]⁺ cation is a remarkably constant feature of all structures, as is its tendency to close-pack in sheets normal to their P-Ag-P axes.The far-IR spectra of the above species and of several related complexes have been recorded and assigned. The vibrational modes of the single stranded polymeric AgX chains in [XAg(pip)₂]_(∞|∞) (X = Cl, SCN) are discussed, and the assignments ν(AgX) = 155, 190 cm⁻¹ (X = Cl) and 208 cm⁻¹ (X = SCN) are made. The ν(AgX) and ν(AgN) modes in the cubane tetramers [XAg(pip)]₄ (X = Br, I) are assigned and discussed in relation to the assignments for the polymeric AgX:pip (1:2) complexes, and those for the polymeric [XAg(quin)]_(∞|∞) (X = Cl, Br) compounds. The far-IR spectra of [Ag(tmpp)₂]₂[Ag₅I₇(py)₂] and its corresponding 2-methylpyridine complex show a single strong band at about 420 cm⁻¹ which is assigned to the coordinated tmpp ligand in [Ag(tmpp)₂]⁺, and a partially resolved triplet at about 90, 110 and 140 cm⁻¹ which is assigned to the ν(AgI) modes of the [Ag₅I₇L₂]²⁻ anion. An analysis of this pattern is given using a model which has been used previously to account for unexpectedly simple ν(CuI) spectra for oligomeric iodocuprate(I) species.     

The structural definition of adducts of stoichiometry AgX:dppf (1:1)(n), X = simple anion, dppf = bis(diphenylphosphino)ferrocene

Single crystal X-ray structural characterizations are recorded for an array of adducts of the form AgX:dppf (1:1)_(n), X = simple (pseudo-)halide or oxy-anion, ‘dppf’ = bis(diphenyl phosphino)ferrocene, for adducts X = Cl (new phase), Br, I, SCN, OCN, CN, NO₃ (new phase), O₂CCH₃, n = 2, the form being dimeric [(dppf-P,P′)Ag(μ-X)₂Ag(P,P′-dppf)], for X = I, SCN, [Ag(μ-X)₂(P-dppf-P′)₂Ag′]; for X = O₂CCF₃, n = ∞, the form is an extended polymer: ?Ag(O · CO · CF₃)(P-dppf-P′)Ag′(O?. A dichloromethane solvate phase of CuI:dppf (1:1)₂ (also centrosymmetric) is also recorded. Synthetic procedures for all adducts have been reported. All compounds have been characterized both in solution (¹H, ¹³C, ³¹P NMR, ESI MS) and in the solid state (IR). The topology of the structures in the solid state was found to depend on the nature of the counterion.     

New oligo-/poly-meric forms for MX:dpex (1:1) complexes (M = Cu, Ag; X = (pseudo-)halide; dpex = Ph2E(CH2)xEPh2, E = (P), As; x = 1, 2)

Single-crystal X-ray structural characterizations of MX:dpam (1:1) (‘dpam’ = Ph₂AsCH₂AsPh₂) are reported for MX = AgCl, Br; CuI, CN/Cl (all isomorphous) and AgI, AgSCN, CuSCN arrays, all being of the novel form [(μ-X){M(μ-X)(As-dpam-As′)₂M′}]_∞, essentially the familiar M(E-dpem-E′)₂M′ binuclear array with both ‘bridging’ and (linking) ‘terminal’ (pseudo-)halides involved in the polymer. A different arrangement of bridging and linking entities is found with AgX:dpae (1:1)_2(∞|∞), X = Br, NCO, ‘dpae’ = Ph₂As(CH₂)₂AsPh₂, now comprising [M(μ-X)₂(As-dpae-As)M] kernels linked by As-dpae-As′, while in the thiocyanate analogue units are linked by the dpae ligands into a two-dimensional web. Synthetic procedures for all adducts have been reported. All compounds have been characterized both in solution (¹H, ¹³C, ³¹P NMR, ESI MS) and in the solid state (IR).     

Synthesis and structural characterization of adducts of silver(I) nitrate with ER3 (E = P, As, Sb; R = Ph, cy, o-tolyl, mes) and oligodentate aromatic bases derivative of 2,2′-bipyridyl, L, AgNO3:ER3:L (1:1:1)

Twenty-one adducts of the form AgNO₃:ER₃:L (1:1:1) (E = P, As, Sb; R = Ph, cy, o-tolyl, mes; L = 2,2′-bipyridyl (‘bpy’)-based ligand), together with AgNO₃:Pcy₃:tpy (2:2:1) and AgNO₃:PPh₃:tpy (1:2:1) (‘tpy’ ≡ (2,2′:6,2″-terpyridine)), have been synthesized and characterized by analytical, spectroscopic (IR, far-IR, ¹H and ³¹P NMR) and single crystal X-ray diffraction studies. The resulting complexes are predominantly of the form , with trigonal EAgN₂ coordination environments, the planarity of which is perturbed by the approach of the nitrate anion. The nitrate ion shows uni- or (semi-)bidentate coordination, excepting the complex AgNO₃:P(o-tol)₃:dpca (1:1:1) (dpca = bis(2-picolyl)amine) where the anion is uncoordinated, the donor dpca being a pincer-tridentate. The complex AgNO₃:Pcy₃:tpy (2:2:1), also reported, is dinuclear with a bridging unidentate nitrate and a terpyridine, the latter bridging through its central ring, with the peripheral rings forming chelates to either side, whereas the complex AgNO₃:PPh₃:tpy (1:2:1) is ionic with a five-coordinate silver, bonded to tridentate tpy and two phosphines.     

Synthesis and structural characterization of the adducts of silver(I) perchlorate and nitrate with triphenylphosphine and bis(pyrazolyl)methane ligands of 1:1:1 stoichiometry

Six new adducts of the form AgX:PPh₃:H₂C(pz^x)₂ (1:1:1) (H₂C(pz^x)₂ = H₂C(pz)₂ = bis(pyrazolyl)methane or H₂C(pz^Me2)₂ = bis(3,5-dimethylpyrazolyl)methane; X = ClO₄, NO₃, SO₃CF₃) have been synthesized and characterized by analytical, spectroscopic (IR, far-IR, ¹H and ³¹P NMR) and two of them also by single crystal X-ray diffraction studies for comparison with counterpart adducts with 2,2′-bipyridyl (‘bpy’) derivatives reported in a previous paper, the bpy-derived ligands forming five-membered chelate rings, while the present H₂C(pz^x)₂ should, potentially, form six-membered rings. Such is the case, the two adducts exhibiting quasi-planar N₂AgP coordination environments, perturbed by the approach of the oxyanion, unidentate in the case of the perchlorate but, in the case of the nitrate, an interesting disordered aggregate of differing unidentate modes.     

Syntheses, structures and vibrational spectroscopy of some 1:1 and 1:2 adducts of silver(I) oxyanion salts with 2,2′-bis(pyridine) chelates

Syntheses and room-temperature single-crystal X-ray structure determinations are recorded for a number of adducts of 1:1 stoichiometry of silver(I) oxyanion salts (perchlorate, nitrate, trifluoroacetate (‘tfa’) (increasing basicity)) with 2,2′-bis(pyridine) ligands (2,2′-bipyridyl, ‘bpy’; 2,2′-biquinolyl, ‘bq’; 2,2′-dipyridylketone, ‘dpk’; 2,9-dimethylphenanthroline, ‘dmp’). The adducts take two forms: (a) neutral mononuclear molecules, in which the 2,2′-bis(pyridine) ligand behaves as a chelate, with the silver coordination number dependent on the denticity of the anion; these are Agtfa:bpy (1:1) and AgClO₄:bq (1:1) (and various (ionic) acetonitrile or pyridine solvates AgClO₄:bq/dmp:MeCN/py (1:1:1), in which the solvent molecules are coordinated); and (b) one-dimensional polymers. The latter are diverse: in AgClO₄:bpy, dpk (1:1), the anion is discrete, the polymer made up of an array of two-coordinate silver atoms linked by bpy ligands twisted about their central connecting element. In AgNO₃:bpy, bq (1:1), the bpy ligands are chelating with the oxyanions bridging, cf. previously reported AgNO₃:dpk (1:1), in which the nitrate chelates the metal, with the dpk bridging, chelating N,O to one silver, while the other nitrogen bridges to the next. With Agtfa, a novel binuclear adduct has been isolated in conjunction with the hydrated ligand, Agtfa:dpk:(dpk · H₂O) (1:1:2). The far-IR spectra of several of these complexes show bands that can be assigned to the ν(AgN) modes, the positions of these bands correlating well with the relative Ag-N bond lengths.Syntheses and single-crystal X-ray structural characterizations are also reported for various adducts of silver(I) perchlorate, nitrate and trifluoromethanesulfonate with bpy, bq, ‘phen’ (= 1,10-phenanthroline), and ‘dmp’, of stoichiometry AgX:L (1:2). In each case the complex is ionic [AgL₂]X; the silver atom is four-coordinate, but diverse and remarkable variations in stereochemistries associated with changes in the interligand N-Ag-N angles, presumably influenced by the different packing arrangements, are observed.     

Extended molecular networks based on Zn and Cd imparting N-substituted imidazole

Synthesis of complexes with the formulations [M(CPI)₂Cl₂] (M = Zn, 1; M = Cd, 4) and [M(CPI)₆](X)₂ (M = Zn, X = NO₃⁻, 2; X = ClO₄⁻, 3; M = Cd, X = NO₃⁻, 5; X = ClO₄⁻, 6) have been achieved from the reactions of MCl₂, M(NO₃)₂·xH₂O and M(ClO₄)₂·xH₂O (M = Zn, Cd) with 1-(4-cyanophenyl)-imidazole (CPI). Complexes 1-6 have been characterized by elemental analyses and spectral studies (IR, ¹H, ¹³C NMR, electronic absorption and emission). Molecular structures of 1, 2, 3 and 6 have been determined crystallographically. Weak interaction studies on the complexes revealed presence of various interesting motifs resulting from C-H···N, C-H···Cl and π-π stacking interactions. The complexes under study exhibit strong luminescence at ∼450 nm in DMSO at room temperature.     

Transition metal halide salts of 8-methylquinolinium: Synthesis and structures of (8-methylquinolinium)2 MX4·nH2O (M = Cu, Co, Zn; X = Cl, Br; n = 0, 1)

The reactions of metal(II) chlorides and bromides with 8-methylquinoline (8-mequin) in neutral and acidic solutions were investigated. The reaction with ZnCl₂, ZnBr₂, CoCl₂, CoBr₂, CuCl₂ or CuBr₂ with the appropriate HX in water or aqueous ethanol gave complexes of the formula (8-mequin)₂MX₄ (1, M = Cu, X = Cl; 2, M = Cu, X = Br; 3, M = Co, X = Cl; 4, M = Co, X = Br) or (8-mequin)₂ZnX₄·nH₂O (5, X = Cl, n = 0; 6, X = Br, n = 0; 7, X = Cl, n = 1; 8, X = Br, n = 1). Crystals of 1, 2 and 4-8 suitable for single crystal X-ray diffraction were obtained and the structures reported. Compounds 1 and 2 crystallize in the monoclinic space group C2/c, while 4-8 crystallize in the triclinic space group, . Variable temperature magnetic susceptibility data indicate very weak interactions for the copper compounds 1 and 2, while the magnetic behavior of 3 and 4 is dominated by single ion anisotropy, with weaker antiferromagnetic interactions.     

Synthesis, spectroscopy and structural characterization of silver(I) complexes containing unidentate N-donor azole-type ligands

From the interaction between azole-type ligands L and AgX (X = NO₃ or ClO₄) or [AgX(PPh₃)_n] (X = Cl, n = 3; X = MeSO₃, n = 2), new ionic mononuclear [Ag(L)₂]X and [Ag(PPh₃)₃L][X] or neutral mono-([Ag(PPh₃)_nL(X)]) or di-nuclear ([{Ag(PPh₃)(L)(μ-X)}₂]) complexes have been obtained which have been characterized through elemental analysis, conductivity measurements, IR, ¹H NMR and, in some cases, also by ³¹P{¹H} NMR spectroscopy, and single-crystal X-ray studies. Stoichiometries and molecular structures are dependent on the nature of the azole (steric hindrance and basicity), of the counter ion, and on the number of the P-donor ligands in the starting reactants. Solution data are consistent with partial dissociation of the complexes, occurring through breaking of both Ag-N and Ag-P bonds.     

Synthesis and characterization of a series of N3O-ligated mononuclear Mn(II) halide complexes

Treatment of a N₃O-donor chelate ligand (mpppa = N-methyl-N-((6-pivaloylamido-2-pyridyl)methyl)-N-(2-pyridylethyl)amine; bpppa = N-benzyl-N-((6-pivaloylamido-2-pyridyl)methyl)-N-(2-pyridylmethyl)amine) with equimolar amounts of Mn(ClO₄)₂ · 6H₂O and Me₄NX (X = Cl, Br, I) in methanol resulted in the production of a series of mononuclear Mn(II) halide complexes of the formula [(L)Mn-X(CH₃OH)]ClO₄ (L = mpppa or bpppa). X-ray crystallographic studies of [(mpppa)Mn-Cl(CH₃OH)]ClO₄ · CH₃OH (2 · CH₃OH), [(mpppa)Mn-Br(CH₃OH)]ClO₄ · CH₃OH (4 · CH₃OH), [(mpppa)Mn-I(CH₃OH)]ClO₄ · CH₃OH (6 · CH₃OH), and [(bpppa)Mn-I(CH₃OH)]ClO₄ · O₂(CH₂CH₃)₂ (7 · O(CH₂CH₃)₂) revealed for each a mononuclear Mn(II) center having tetradentate coordination of the chelate ligand, one coordinated halide anion, and one molecule of coordinated methanol. An increase in the Mn-X distance through the halide series (Cl, Br, I) correlates linearly with the increase in the radius of the anion. The magnetic moment of each halide complex, measured via Evans method in methanol, is consistent with the presence of a high-spin distorted octahedral Mn(II) center. The EPR features of the halide complexes in methanol do not change as a function of the nature of the halide coordinated to the Mn(II) center.     

Syntheses, spectroscopic and structural characterization of some (solvated) binuclear adducts of the form Ag(oxyanion):dpem(:S) (1:1(:x))2 (oxyanion = ClO4, F3CCO2, F3CSO3; dpem = Ph2E(CH2)EPh2 (E = P, As))

Syntheses, spectroscopic (IR, NMR and ESI MS) and single crystal X-ray structural characterizations are reported for a wide variety of adducts of Ag(oxyanion):dpem(:S) (1:1(:n))₂ (oxyanion = ClO₄, F₃CCO₂ (tfa) F₃CSO₃ (tfs); dpem = Ph₂E(CH₂)EPh₂) stoichiometry among which the basic Ag(Ph₂E(CH₂)EPh₂)₂Ag core is diversely perturbed by interactions with anions and solvent molecules. ESI MS and ³¹P NMR spectroscopy indicated that dinuclear species also exist in solution.     

Synthesis, spectroscopic and structural characterization of adducts of stoichiometry CuX:dppe (1:2) (X = I, ClO4, BH4, O3SCF3, SCN, dppe = Ph2P(CH2)2PPh2)

Syntheses and spectroscopic features (IR, NMR and ESI MS) are reported for five 1:2 adducts of CuX with dppe (X = I, ClO₄, NCS, O₃SCF₃ (tfs) BH₄; dppe = Ph₂P(CH₂)₂PPh₂). ESI MS and ³¹P NMR spectroscopy indicate that these species dissociate in solution yielding free diphosphine and 3:2 species. A single crystal X-ray structure determination has been carried out on Cu(dppe)₂NCS defining a four-coordinate complex of the form [(P,P′-dpex)M(P-dpex)X] for M = Cu, the thiocyanate being N-bound; the ionic [Cu(P,P′-dppe)₂]tfs has also been structurally characterized.     

Synthesis, characterization, and reactivity of (π-allyl)palladium(II) wrap-around complexes with 1,3-dienes

Synthesis of a series of cationic “wrap-around” complexes, η³-, η²- (CH₂-CH-CHR-CH₂-CH₂-CHCHX) Pd(II)L⁺ (R = H, CH₃; X = H, Cl, CO₂Me; L = PPh₃, P(C₄H₄N)₃), is described. These chelate complexes were prepared by exposure of π-allyl chloride dimers, (η³-(CH₂-CX-CH₂)PdCl)₂, to either 1,3-butadiene or isoprene to yield π-allyl chloride dimers of the type (η³-CH₂CHCRCH₂CH₂CH = CH(X)PdCl)₂ which result from insertion of the diene into each π-allyl unit. Abstraction of chloride with either AgSbF₆ or NaB(Ar_F)₄ in the presence of L gives the cationic wrap-around complexes in high yields. Single crystal X-ray diffraction studies of 8a (R = -CH₃, X = -Cl, L = PPh₃) and 9a (R = -H, X = -Cl, L = PPh₃) show that Pd(II) adopts essentially a square planar geometry and the chelate arm occupies a syn orientation with respect to the allyl unit. Exposure of these wrap-around complexes to nitriles of differing basicities displaces the chelated alkene to varying extents and allows assessment of the relative strengths of chelation as a function of substituents, X and R. Initial rapid displacement of the chelated alkene yields a syn-π-allyl isomer which equilibrates with the anti-π-allyl isomer which cannot close to form a chelate. Treatment of 8b with 1,3-butadiene gives not polybutadiene but 2-chloro-4-methyl-1,E-4,6-heptatriene and 2-chloro-4-methyl-1,Z-4,6-heptatriene. Formation of these trienes is first-order in butadiene. This reaction serves as a model for chain-transfer in the polymerization of butadiene.