Showing papers in "Transition Metal Chemistry in 1996"

E.s.r. studies on acylhydrazine and hydrazone copper(II) sulfate complexes

Abstract: CuII complexes of the [CuL2(SO4)]·nH2O and [CuL′(SO4)(H2O)2]·nH2O type, where L = benzoylhydrazine (PhCONHNH2; BH) or iso-propanone benzoylhydrazone (PhCONHN:CMe2; IBH), L′= iso-nicotinoylhydrazine (NC5H4CONHNH2; INH) or isopropanone iso-nicotinoylhydrazone (NC5H4CONHN: CMe2; IINH); n = 0–2, were prepared and characterized by elemental analyses, molar conductances, and electronic, e.s.r. and i.r. spectral measurements. The electronic and e.s.r. spectra suggest a tetragonally distorted octahedral geometry in the solid state as well as in DMSO solution. The e.s.r. data also reveal an axial symmetry for most of the complexes in the solid state and in DMSO solution at 300 and 77 K, while the complex of IBH is isotropic at 300 K. The ΔMs = 2 transition observed for this complex suggests that it is a dimer. BH and INH bond to CuII through the C-O and NH2 groups, whereas IBH and IINH bond through C-O and C-N groups.

Tetradentate Schiff base oxovanadium(IV) complexes

Abstract: Eleven oxovanadium(IV) complexes of tetradentate Schiff bases, obtained by condensating two moles of an o-hydroxycarbonyl compound with a diamine, have been prepared and characterized by elemental analysis, m.p., and i.r. and electronic spectra. The i.r. and electronic spectra of the free ligand and the complexes are compared and discussed. The Gaussian analysis of the vis. spectra of the complexes, normally C1 or Cs, in MeCN yielded four peaks at ca. 12000, 15000, 17700 and 20000–23000cm−1, assigned to the four d-d transitions.

Copper(II) complexes of 2-formyl-,2-acetyl- and 2-benzoylpyridine N (4)- o-, N (4)- m-, N (4)- p -chlorophenylthiosemicarbazones

Abstract: CuII complexes of 2-formyl, 2-acetyl- and 2-benzoylpyridine N(4)-o-, N(4)-m- and N(4)-p-chlorophenylthiosemicarbazones, coordinated either as a neutral or monoanionic ligand, have been prepared and characterized. I.r., electronic and e.s.r. spectra of the complexes, as well as 1H- and 13C-n.m.r. spectra of the thiosemicarbazones, have been obtained. Both the thiosemicarbazones and their CuII complexes show either modest or no growth inhibitory activity against Paecilomyces variotii. Some of the thiosemicarbazones demonstrated significant activity against tumour cell strains.

Copper(II) complexes of 2-formyl-, 6-methyl-2-formyl- and 2-benzoylpyridine N (4)-(2-methylpyridinyl)-, N (4)-(2-ethylpyridinyl)-and N (4)-methyl(2-ethylpyridinyl)thiosemicarbazones

Abstract: The title complexes of general formula [Cu(HL)Cl2] or [Cu(L)Cl] have been isolated and characterized by 1H and 13C-n.m.r., i.r. and electronic spectra. The i.r., electronic and e.s.r. spectral data for the CuII complexes are compared with those of previously studied complexes. The antitumour and antiviral activities of the thiosemicarbazones and their complexes are discussed.

From novel complexing conditions to novel coordination compounds of nickel(ii) with dithiooxamide and its bulky analogues

Abstract: Novel complexing processes in the NiII-dithiooxamide, NiII-N,N′-diphenyldithiooxamide and NiII-quinoxaline-2,3-dithiol systems, which have not been used in coordination chemistry before, namely complexing in a nickel(II)hexacyanoferrate(II) gelatin-immobilized matrix in contact with an aqueous solution of the corresponding ligand, have been studied. Under these specific conditions, in the NiII-dithiooxamide system, five different coordination compounds are formed, four of which are insoluble in H2O. In the NiII-quinoxaline-2,3-dithiol system, three different complexes formed (each of them insoluble in H2O) and, in the NiII-diphenyldithiooxamide system, only one insoluble complex is formed. Whereas, complexing in solution or the solid phase, formation of only one complex is observed in each of systems cited

Medicinal chemistry and pharmacology of gold compounds

Abstract: The only current clinical application for gold drugs is in the treatment of rheumatic diseases, primarily rheumatoid arthritis. Little has changed in this area since the introduction of the orally available gold drug auranofin in 1985. There has been considerable research effort to find alternative therapeutic applications for gold drugs, particularly for the treatment of cancer, but after promising early indications the lead candidate [Au(dppe)2]Cl failed to enter clinical trials due to cardiotoxicity. Despite this setback research in this field has not abated. Recent work in our own laboratory has indicated that stable gold(III) compounds have activity in disease models of human cancer and this may be the way forward in this area. Gold compounds also have potential as antimicrobial agents, particularly against topical infections. The most interesting advances in the pharmacology of gold drugs have come from studies on their mechanism of action. The diverse effects of gold drugs on the immune system have been known for some time but there has been no satisfactory biochemical explanation for these observations. Recent work on the effect of gold compounds on gene transcription provides a new clue to this mechanism. After 60 years of chrysotherapy perhaps an improved understanding of the molecular and biochemical mechanism of gold compounds will provide the impetus for new advances in the medical use of gold drugs.

Binuclear copper(II) complexes of 5-nitrosalicylaldehyde N(3)-substituted thiosemicarbazones

Abstract: Binuclear copper(II) complexes with six 5-nitrosalicylaldehyde N(3)-substituted thiosemicarbazones have been prepared and characterized. I.r., electronic and e.s.r. spectra of the complexes, as well as i.r., electronic, and 1H-and 13C-n.m.r. spectra of the thiosemicarbazones, have been obtained. The crystal structure of a monomeric copper(II) complex of 5-nitrosalicylaldehyde piperidyl-thiosemicarbazone, H25NO2Sapip, grown from DMF solution, has been solved. Neither the thiosemicarbazones or their binuclear copper(II) complexes show growth inhibitory activity against Aspergillus niger, but the copper(II) complexes show some activity against the fungus Paecilomyces variotii.

Formation of cobalt(II), nickel(II) and copper(II) chloro complexes in alcohols and the Irving-Williams order of stabilities

Abstract: CoII chloro complexes were studied in MeOH at 25 °C and at constant ionic strength of 1 mol dm−3. Formation of three complexes is postulated for which the overall stability constants are calculated: logβ1 = 1.2, log β2 = 1.7 and log β3= 1.4. The electronic spectra and the formation curves of the identified species are presented for the first time in this medium. The results are compared with those obtained in other alcohols and increasing stability with increasing molecular weight of the solvents is established. Further comparative study showed that the maximum stability of the chloro complexes is found with the CuII ion as the central atom. This confirms the Irving-Williams order of stabilities for the first transition metal complexes in this alcoholic medium and the result is explained in terms of the second ionization potential of the elements.

Synthesis, characterization and antitumour properties of metal(II) solid complexes with Morin

Abstract: Six metal(II) complexes with Morin ML2·nH2O [L = Morin(2′-OH group deprotonated); M = Mn, Co, Ni, Cu, Zn, or Cd; n = 2 or 3] have been synthesized and characterized by elemental analysis, molar conductance, i.r., 1H-n.m.r., t.g.-d.t.a and u.v.-vis. spectroscopic techniques and by fluorescence analysis. Comparative antitumour activities of Morin·2H2O and two complexes [ZnL2·3H2O and CuL2·2H2O] were tested by in vitro screening. The results show that the inhibitory ratio of complexes against the tested tumour cells was higher than that of Morin.

Metal complexes of salicylhydroxamic acid: equilibrium studies and synthesis

Abstract: The complex formation equilibria involved in the binary and ternary systems of MII-SHAM and MII-SHAM-L [M = Cu, Ni, Co, Zn, Cd, Mn, Hg, Ca or UO2; SHAM = salicylhydroxamic acid; L = the ligating agent, N-(2-acetamido)iminodiacetic acid (ADA), iminodiacetic acid (IDA) or nitrilotriacetic acid (NTA)] were investigated by the potentiometric technique at 25 °C and ionic strength 0.1 m NaNO3. The results indicate the formation of 1∶1 and 1∶2 (metal ion:ligand) SHAM complexes. The formation of mixed-ligand complexes followed a stepwise mechanism, whereby an ML complex was first formed, followed by the ligation of SHAM. The relative stability of the mixed-ligand complex was compared with that of the binary complex. The concentration distribution of the complexes possibly formed in solution was evaluated. Solid complexes of SHAM were prepared and characterized by microanalysis, conductivity, i.r., electronic and n.m.r. spectroscopies, and magnetic susceptibility measurements.

Copper(II) complexes of 2-formyl-, 2-acetyl- and 2-benzoyl-pyridine N(4)-phenyl-, N(4)-o-methoxyphenyl-, N(4)-p-methoxy-phenyl- and N(4)-p-nitrophenylthiosemicarbazones

Abstract: CuII complexes of 2-formyl-, 2-acetyl- and 2-benzoylpyridine N(4)-phenyl-, N(4)-o-methoxyphenyl-, N(4)-p-methoxyphenyl- and N(4)-p-nitrophenyltniosemicarbazones, coordinated either as neutral or monoanionic ligands, have been prepared and characterized. I.r., electronic and e.p.r. spectra of the complexes, as well as 1H-and 13C-n.m.r. spectra of the thiosemicarbazones, have been obtained. Both the thiosemicarbazones and their complexes show either modest or no growth inhibitory activity against Paecilomyces variotii. However, some of these thiosemicarbazones possess significant activity against a number of tumour cell strains.

Coordination behaviour of 2-guanidinobenzimidazole towards cobalt(II), nickel(II), copper(II) and zinc(II). An experimental and theoretical study

Abstract: The following coordination compounds derived from 2-guanidinobenzimidazole (2GB) (1); [Ni(2GB)2]Cl2· H2O, (2); [Ni(2GB)2]Br2·3H2O, (3); [Ni(2GB)2-(NO3)2, (4); [Ni(2GB)2](OAc)2, (5); [Cu(2GB)Cl2], (6); [Cu(2GB)Br2], (7); [Cu(2GB)2]Br2·2H2O, (8); [Cu(2GB)2](NO3)2·H2O, (9); [Cu(2GB)2](OAc)2· H2O, (10); [Zn(2GB)Cl2]·H2O, (11); [Zn(2GB)Br2]·H2O, (12); [Co(2GB)Cl2(H2O)2]·5H2O, (13); [Co-(2GB)2Cl2]·3H2O, (14); [Co(2GB)2(H2O)2](NO3)2· 4H2O, (15); and [Co(2GB)2(H2O)2](OAc)2, (16) have been synthesized and characterized by i.r. and electronic spectroscopy. In addition (6)–(10) were analysed by e.p.r. The X-ray diffraction structure of compound (4) was obtained. It crystallizes in the monoclinic system, C2/c (a = 22.511(7), b = 6.735(6) and c= 15.345(5)A, β =115.31(3)°, Z = 4, final R = 0.0360 and R w = 0.0388 for 1167 observed independent reflections). The nickel(II) atom coordinates two ligands in a square-planar geometry through the imidazolic N(3) and the guanidino N(12). The probable ligand isomers involved in the coordination were determined by theoretical calculations, and the possible structures of the coordination compounds were investigated in order to verify that the experimentally proposed structures were stable. Two different types of coordination compounds were found. One, where the ligand is chelating through the imidazolic N(3) and the guanidino N(12), which is the case for most of the complexes [(2)–(13)]. With only one ligand in the coordination sphere, the structure was either tetrahedral (copper and zinc chloride and bromide complexes) or octahedral (cobalt). With two chelating 2GB units a square-planar geometry was stabilized [(2)–(5) and (8)–(10)]. The second type of coordination behaviour was observed in the cobalt compounds [(14)–(16)]. Here the ligand coordinates monodentate through the imidazolic N(3); the structure is tetrahedral.

Regioselective homogeneous hydrogenation of heteroaromatic nitrogen compounds by use of [RuH(CO)(NCMe)2(PPh3)2]BF4 as the precatalyst

Abstract: The complex [RuH(CO)(NCMe)2(PPh3)2]BF4 (1) is an efficient and regioselective catalyst precursor for the hydrogenation of polyaromatic nitrogen compounds such as quinoline (Q), isoquinoline (iQ), indole (ln), 5,6- and 7,8-benzoquinoline (BQ) and acridine (A) under relatively mild reaction conditions (125 °C, 4 atm H2). The order of individual initial rates was: A > Q > 5,6-BQ > 7,8-BQ > ln > iQ, reflecting both steric and electronic effects. For the regioselective homogeneous hydrogenation of A to 9,10-dihydroacridine (DHA) catalysed by complex (1), a kinetic study was carried out; the experimentally determined rate law was r = k 1 [Ru] [H2]. These findings are consistent with a mechanism involving the hydrogenation of [RuH(CO)(A)(NCMe)(PPh3)2]BF4 to yield DHA and the unsaturated species [RuH(CO)(NCMe)(PPh3)2]BF4 in the rate-determining step.

Kinetics of oxidation of l -lysine and l-phenylalanine by anodically-generated manganese(III) in aqueous ethanoic acid

Abstract: [Mn(OAc)3] was prepared by the electrolytic oxidation of Mn(OAc)2 in aqueous AcOH. The electrogenerated MnIII species was characterized by spectroscopic and redox potential studies. The kinetics of oxidation of the amino acids (AA) l-lysine and l-phenylalanine by the MnIII in aqueous AcOH were investigated and the rate law: $$rate = k\left[ {Mn^{III} } \right]^x \left[ {AA} \right]_0 \left[ {OAc^ - } \right]^x \left[ {H^ + } \right]^{ - x} $$ where x = 0.5 was observed. The effects of addition of the reduced product [MnII] and anions such as F-, Cl- and ClOinf4sup−were investigated. Solvent isotope studies in D2O (40% v/v) showed that the reaction rate decreases in D2O medium. A mechanism consistent with the observed results is proposed and discussed.

Synthesis and spectroscopic studies of trinuclear uranyl complexes with compartmental ligands H4L derived from 2,6-dipicolinoyl-hydrazine and 4-acyl-1-phenyl-3-methyl-pyrazolones-5 (where acyl = benzoyl, acetyl, iso-butyryl or iso-valeroyl)

Abstract: The potentially trinucleating ligands H4L were synthesized in situ by reacting 2,6-dipicolinoyl-hydrazine with 4-acyl-1-phenyl-3-methyl-pyrazolones-5 (acyl = benzoyl, acetyl, iso-butyryl or iso-valeroyl) in a 1∶2 molar ratio. These ligands react with an excess of uranyl acetate dihydrate to yield trinucleating uranyl complexes [(UO2)3(L)(DMF)4(OAc)2] · (H2O)5. Tentative structures for the complexes have been proposed on the basis of elemental analyses, i.r. and electronic data. The force constant (f) for the vas(O=U=O) vibration and values for the U-O distance, RU-O, are calculated. The spectral studies support the trinuclear structure.

Kinetics and mechanism of oxidation of (aqua-2-aminomethyl-pyridine) chromium(III) by N-bromosuccinimide

Abstract: The kinetics of oxidation of (aqua-2-aminomethyl-pyridine) CrIII by N-bromosuccinimide (NBS) in aqueous solution to yield chromium(VI) has been studied spectrophotometrically over the 25–40 °C range. The reaction rate is first order with respect to both [NBS] and [CrIII], and increases with increasing pH between 7.6 and 8.6. The thermodynamic activation parameters were calculated. The experimental rate law is consistent with a mechanism in which the deprotonated [Cr(L)2(OH)]2+ was considered to be the most reactive form compared to its conjugate acid. It is assumed that electron transfer takes place via an inner-sphere mechanism.

New substituted titanocene, zirconocene and hafnocene dichlorides

Abstract: Twentytwo new substituted metallocene Cp1Cp2MCl2 (M = Ti, Zr or Hf) dichlorides have been prepared and the catalytic activity of some of them in alkene polymerization has been primarily evaluated

Synthesis, characterization and antitumour studies on N-salicyl-N′-thiobenzohydrazide and its copper(II) complex

Abstract: The new potential tetradentate ligand N-salicyl-N′-thiobenzohydrazide (H2SBTH) and its Cu complex, [Cu(SBTH)], have been prepared and characterized by physico-chemical studies. In vivo antitumour activity of [Cu(SBTH)] has been tested against breast tumour in C3H/J strain mice; LD50 values were also calculated. The cytotoxicity and antitumour effect of [Cu(SBTH)] is a maximum at 100 mg kg-1 body weight injected intraperitoneally in mice carrying breast tumour. In vitro results of the ligand and the complex on P-815 (murine mastocytoma) and K-562 (human erythroleukemia cells) indicate that these compounds show significant inhibition on 3H-thymidine and 3H-uridine incorporation in DNA and RNA in these tumour cells. Light microscopic study of the treated tumour mass demonstrated that certain cellular degradation, such as disappearance of mitotic figures, loss in cellular compactness, distortion of nucleus and disruption of cytoplasmic boundaries, take place in complex-treated mice with tumours.

Binuclear iron(III)-iron(III) complexes with the tetradentate Schiff base N,N′-bis (salicylidene)ethylenediamine and dicarboxylic acids or dithiooxamide as bridging ligands

Abstract: Complexes of the type [(Fe(salen))2L]·xH2O (L = glutarate, adipate, pimelate or suberate dianion, x = 0 or L = dithio oxamidate dianion, x = 2) have been prepared and studied by elemental analyses, i.r. and electronic spectra, and magnetic measurements. A dimeric structure with an octahedral arrangement of FeIII (S = 5/2) is proposed. Some of the complexes have been characterized by temperature-dependent magnetic susceptibilities, but an antiferromagnetic exchange interaction was found only for [(Fe(salen))2dta]·2H2O (H2dta = dithio-oxamide).

Synthesis and spectroscopic studies of complexes containing the Schiff base 1-acetylferrocene(thio)semicarbazone

Abstract: [RuCl2(CO)2] n reacts with the Schiff base 1-acetylferrocenethiosemicarbazone, [Fe(η-Cp)(η-C5H4MeC=NN-HCSNH2)] to give [Fe(η-Cp)(η-C5H4MeC=NN-HCSNH2)RuCl2(CO)2] and with 1-acetylferrocenesemicarbazone [Fe(η-Cp)(η-C5H4MeC=NN-HCSNH2)] to give [Fe(η-Cp)(η-C5H4MeC=NN-HCSNH2)RuCl2-(CO) 2]. Spectroscopic data indicate that the Schiff bases act as bidentate ligands and coordinate to ruthenium via the hydrazinic N and either the S or O atoms, respectively, giving stable heterobimetallic complexes, which have been characterized by i.r. and 1H-n.m.r. spectroscopies, and elemental analyses.

Ternary complexes of N-(2-acetamido)iminodiacetic acid and some aromatic acids. Isolation and stability constants in solution

Abstract: Ternary 1:1:1 complexes of YIII, CoII, NiII, CuII, LaIII, CeIII and UO 2 2+ with N-(2-acetamido)iminodiacetic acid (H2ADA) as primary ligand and salicylic, anthranilic or phthalic acid as secondary ligand are described. The complexes of CoII and CuII were isolated and characterized by microanalysis, molar conductance measurements, thermal analysis, i.r. and u.v.-vis. spectra. The formation constants of the 1∶1∶1 ternary complexes were determined potentiometrically in 20% (w/w) EtOH-H2O at 24 °C. The stabilities of the 1∶1∶1 M n+ :ADA2−:aromatic acid ternary complexes are higher than those of the corresponding 1∶1 M n+ :aromatic acid binary complexes.

Synthesis and properties of cyano-bridged nickel(ii)-iron(iii) complexes

Abstract: Four kinds of novel CN-bridged NiII-FeIII complexes, [NiLn(NC)Fe(CN)5] −, have been synthesized and characterized by elemental analysis, i.r. and u.v.-vis. spectral analysis, and magnetic moments. The formation of cyanide bridges is evident from the i.r. and u.v.-vis. spectra by the appearance of v(CN) shifts and changes in λmax with respect to the mononuclear parent complex [Fe(CN)6]3−. The magnetic properties indicate the existence of magnetic spin interactions between NiII and FeIII through the cyanide bridge.

Crystal and molecular structure, and electronic properties of hexakis(imidazole)copper(II) formate

Abstract: The crystal and molecular structure of [Cu(Im)6] (HCOO)2 (Im = imidazole) has been determined by X-ray diffraction methods. The compound is built of centrosymmetric Cu(Im) inf6 sup2− cations and non-coordinated HCO2 − anions, linked through H-bonds giving a layered structure in the ac plane. The coordination polyhedron around the Cu atoms can be described as a rhombically-distorted octahedron (CuN2N′2N′'2 chromophores). Both electronic and e.p.r. spectra are indicative of an essentially d x2− y2 ground state for the CuII ions. No exchange coupling has been detected down to 4.2 K by means of magnetic susceptibility measurements. This feature is discussed on the basis of the structural data.

Preparation and characterization of metal complexes containing a NS donor ligand derived from S -benzyldithiocarbazate and p -nitrobenzaldehyde. X-ray crystal structure of the nickel(II) chelate

Abstract: A series of metal (Cu, Ni, Zn, Cd and Pd) complexes of a Schiff base ligand derived from S-benzyldithiocarbazate and p-nitrobenzaldehyde were prepared and characterized. The Schiff base acts as a single negatively-charged bidentate ligand forming stable neutral metal complexes. Magnetic and spectroscopic data suggest a square planar structure for the CuII, NiII and PdII chelates. Single X-ray diffraction analysis of the NiII chelate established that the Schiff base loses a proton from its tautomeric thiol form and coordinates to the metal via the thiolato sulfur and β-nitrogen. The geometry around NiII is square planar with two equivalent Ni-N and Ni-S bonds; the two nitrobenzyl rings and the coordination plane are almost isoplanar, giving a delocalized electronic system.

Equilibrium and kinetic studies of cobalt(II) complexation by folic acid

Abstract: The equilibrium and kinetics of the complexation of CoII by folic acid have been studied at 25 °C, the ionic strength being regulated with KNO3 in the 5.6–7.3 pH range. Kinetic studies were performed using the stopped-flow method. Under our experimental conditions one process was observed; a reaction which took place within a few seconds. The results are consistent with the formation of a 1∶1 complex between the reactants and a mechanism is proposed to account for the observed behaviour. Equilibrium constants for the CoII and folic acid system, as well as activation parameters, are reported.

Nickel(II) and copper(II) complexes of ONS ligands formed from 2-hydroxyacetophenone and S-alkyldithiocarbazates and the X-ray crystal structure of the [Ni(Ap-SMe)py] complex (Ap-SMe = anion of the 2-hydroxyacetophenone Schiff base of S-methyl-dithiocarbazate)

Abstract: New nickel(II) and copper(II) complexes of general formulae [M(Ap-SR)] and [Ap-SR)B] (Ap-SR = dianionic forms of the Schiff bases of 2-hydroxyacetophenone and S-alkyl esters of dithiocarbazic acid; M = NiII or CuII; R = Me or CH2Ph; B = py, phen or dipy have been synthesized and characterized by a variety of physicochemical techniques. Magnetic and spectroscopic data support an oxygen-bridged binuclear structure for the [M(Ap-SR)] complexes. The [M(Ap-SR)py] complexes are four-coordinate and square planar, whereas the [M(Ap-SR)B] complexes (B = phen or dipy) are five-coordinate and probably trigonal bipyramidal. The [Cu(Ap-SR)B] complexes (B = py, phen or dipy) obey the Curie-Weiss law over the 298-93 K range.

Preparation and characterization of mononuclear nickel(ii) and copper(ii) complexes of a hexaazamacrobicyclic ligand

Abstract: The structure of the hexaazamacrobicycle, sarcophagine, (diAMMEsar)·2H2O, formed by extracting Co ion from the [Co(diAMMEsar H2)]Cl5·-H2O cage with 8-hydroxyquinoline, has been determined by elemental analysis, and i.r., u.v.-vis., 1H-n.m.r. and mass spectroscopies. Two octahedral complexes, [M(diAMM-EsarH2)]Cl4·2H2O (M = NiII or CuII), have been prepared and characterized. The e.s.r. spectrum of the CuII complex in the solid state indicates spin-exchange interaction between the CuII ions. However, in CD3OD-D2O (10%) at 77K, the spectrum is characteristic of a compound having axial symmetry (d x 2−y 2).

2,4′-Bipyridyl complexes with silver(I) and copper(II).

Abstract: AgI and CuII complexes with 2,4′-bipyridyl (2,4′-bipy or L) with the general formulae AgL2X (where X = NO inf3 sup− or ClO4 -), CuL2X2·2H2O (X = Cl- or Br-), CuL4SO4·4H2O, CuL4(NO3)2·2H2O and CuL4(ClO4)2·H2O have been isolated pure and characterized by analytical, spectral and magnetic measurements. The thermal decomposition of these complexes was studied under non-isothermal conditions in air.

Synthesis, structure and characterization of binuclear silver(I) complexes

Abstract: Two binuclear AgI complexes, [{Ag(dppp)}2](NO3)2 (1) and [{Ag(dppb)}2(NO3)]2 (2) (dppp = Ph2P(CH2)3PPh2, dppb = Ph2P(CH2)4PPh2], were synthesized and characterized by elemental analysis, t.g., i.r. and 31P-n.m.r. spectra. Single crystals of complex (2) were obtained from MeOH-CHCl3. The X-ray crystal structure shows that the dppb ligand is bidentate, with two ligands bridging two metal ions to form a centrosymmetric dimer.