Synthesis and X-ray structural characterization of cobalt(II), copper(II), and silver(I) complexes of triphenylphosphoniopropionate

Four transition-metal carboxylate-like complexes have been synthesized from the reaction of the tertiary phosphine betaine triphenylphosphoniopropionate, Ph₃P⁺(CH₂)₂CO ₂ ^– , with Co(ClO₄)₂· 6H₂O, Cu(ClO₄)₂·6H₂O, Cu(BF₄)₂·xH₂O, and AgClO₄, respectively, and fully characterized by single-crystal X-ray analysis. [CoPh₃P(CH₂)₂CO_{2 4}(H₂O)₂](ClO₄)₂·2H₂O, 1, space groupP¯ l witha=9.195(2),b=13.000(2),c=18.795(3) Å,=102.52(1),=90.12(1),=109.28(2)° andZ=1; [CuPh₃P(CH₂)₂CO_{2 4}][Cu₂ -Ph₃P(CH₂)₂CO₂ -O,O ₄(H₂O)₂] (ClO₄)₆· 4H₂O, 2, space groupP2_l/c witha=14.225(3),b=24.624(6),c=24.297(5) Å,=94.18(1)°, andZ=2; [CuPh₃,P(CH₂)₂CO₂Me₂N(CH₂)₂NMe₂(H₂O)₂](BF₄)₂,3, space groupP2_l/c witha=17.668(2),b=13.454(3),c=15.876(2) Å,=116.45(1)°, andZ=4; [Ag₂Ph₃P(CH₂)₂CO_{2 2}(ClO₄)]₂(ClO₄)₂,4, space groupP¯ l witha=10.925(2),b=13.110(3),c=18.795(3) Å,=82.93(3),=87.45(3),=67.49(3)°, andZ=2. In complex1, the cobalt(II) atom is located in an inversion center and coordinated by four unidentate betaine ligands and a pair oftrans aqua ligands, and strong hydrogen bonds are formed between the aqua ligands and the pendant oxygen atoms of the betaine ligands. In complex2, mononuclear and dinuclear cations coexist in the asymmetric unit. In the mixed-ligand complex3 the betaine ligand acts in the unidentate coordination mode andN,N,N,N-tetramethylethylenediamine (tmen) in the chelate mode. Complex4 contains a discrete centrosymmetric tetranuclear cations in which one pair of betaine ligands act in the bidentate bridging mode and the other in both bidentate and one-atom bridging modes.     

Synthesis and characterization of metal complexes of cobalt(II), nickel(II), copper(II), and silver(I) with syn-thiophene-2-aldoxime

Complexes of syn-thiophene-2-aldoxime (TDH) have been synthesised and characterized on the basis of elemental analysis, molecular weight, conductance, magnetic susceptibility and i. r. spectra. These are [Co(TDH)₄Cl₂], [Co(TD)₂], [Ni(TDH)₄Cl₂], [Ni(TD)₂(TDH)], [Cu(CH₃COO)₂(TDH)]₂, [Cu(TD)(OH)]₂ and AgNO₃ · 2TDH. In these complexes the ligand (TDH) functions as monodentate (coordinating through nitrogen atom) or bidentate (coordinating through the nitrogen and sulphur atoms). The C? S stretching frequency (of the thiophene ring) at 718 cm^?1 may be taken as the criteria for the denticity of this ligand. A shift to lower frequency is observed in the complex if the ligand acts as a bidentate. However, this band is not affected if the ligand acts as monodentate.     

Synthesis and characterization of cyclotetraphosphato complexes of Rh(I), Ir(I), Ru(II), and Pd(II)

The cyclotetraphosphate ion (P(4)O(12)(4)(-)) as a PPN (PPN = (PPh(3))(2)N(+)) salt reacts with [MCl(cod)](2) (M = Rh, Ir; cod = 1,5-cyclooctadiene) to give the dinuclear complexes (PPN)(2)[[M(cod)](2)(P(4)O(12))], in which the two metal moieties are situated trans to each other with respect to the P(4)O(4) ring in the solid state. In solution, however, these complexes exist as mixtures of trans and cis isomers. On the other hand, the P(4)O(12)(4)(-) ion reacts with 4 equiv of [Rh(cod)(MeCN)(x)](+) cation to give the tetranuclear complex [[Rh(cod)](4)(P(4)O(12))], where the four Rh(cod) fragments are bound to the P(4)O(12) platform alternately on both sides of the P(4)O(4) ring. Dinuclear P(4)O(12) complexes of ruthenium and palladium are also synthesized.     

Synthesis and characterization of biacetyldihydrazone complexes of cobalt(II), copper(II), nickel(II) and iron(III)

Summary Biacetyldihydrazone (BdH) complexes [M(BdH)₃](ClO₄)₂ (M=Co^IIor Cu^II) and [M(BdH)₃](NO₃)_2,3 (M = Ni^IIor Fe^III) have been prepared and characterized by chemical analysis, conductance measurements, electronic, i.r. and e.p.r. spectral studies and magnetic subsceptibilities measurements. A mononuclear octahedral configuration is proposed for all complexes studied.     

Coordination modes of 1-allyl benzotriazole: synthesis and characterization of cobalt(II), nickel(II), copper(II), copper(I) and silver(I) complexes

Summary The synthesis and coordination behaviour of 1-allylbenzotriazole (ABT), containing both -donating heterocyclic ring nitrogen(s) and a -bonding olefinic group, has been studied by complexation with Co^II, Ni^II, Cu^II, Cu^I and Ag^I salts. The solid complexes M(ABT)₂X₂ (M=Co, Ni or Cu and X=a counterion) and M(ABT)X (M=Cu or Ag and X=Br, I, or NO₃) have been characterised by¹H-n.m.r. (representative Cu^I species) and other physical data. Different modes coordination for the title ligand have been proposed based upon i.r. data which indicate the participation of a -donating ring nitrogen only in complexes with bivalent metal salts, and the involvement of both the ring nitrogen and the allylic olefinic component in bonding to a monovalent metal ion.¹H-n.m.r. data are qualitatively commensurate with participation of the allyl group in monovalent metal complexes.     

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

Summary Two binuclear Ag^I 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.     

Coordination chemistry of silanedithiolato ligands derived from cyclotrisilathiane: synthesis and structures of complexes of iron(II), cobalt(II), palladium(II), copper(I), and silver(I)

The coordination chemistry of chelating silanedithiolato ligands has been investigated on Fe(II), Co(II), Pd(II), Cu(I), and Ag(I). Treatment of M(OAc)(2) (M = Fe, Co, Pd) with cyclotrisilathiane (SSiMe(2))(3) in the presence of Lewis bases resulted in formation of Fe(S(2)SiMe(2))(PMDETA) (1), Fe(S(2)SiMe(2))(Me(3)TACN) (2), Co(S(2)SiMe(2))(PMDETA) (3), and Pd(S(2)SiMe(2))(PEt(3))(2) (4) (PMDETA = N,N,N',N',N' '-pentamethyldiethylenetriamine; Me(3)TACN = 1,4,7-trimethyl-1,4,7-triazacyclononane). The analogous reactions of M(OAc) (M = Cu, Ag) in the presence of PEt(3) gave rise to the dinuclear complexes M(2)[(SSiMe(2))(2)S](PEt(3))(3) [M = Cu (5), Ag (6)]. Complexes were characterized in solution by (1)H, (31)P[(1)H], and (29)Si[(1)H] NMR and in the solid state by single-crystal X-ray diffraction. Mononuclear complexes 1-3 have a four-membered MS(2)Si ring, and these five-coordinate complexes adopt trigonal-bipyramidal (for the PMDETA adducts) or square-pyramidal (for the Me(3)TACN adduct) geometries. In dimer 6, the (SSiMe(2))(2)S(2)(-) silanedithiolato ligand bridges two metal centers, one of which is three-coordinate and the other four-coordinate. The chelating effect of silanedithiolato ligands leads to an increase in the stability of silylated thiolato complexes.     

Synthesis and reactions of triphenylsilanethiolato complexes of manganese(II), iron(II), cobalt(II), and nickel(II)

Reactions of Fe[N(SiMe(3))(2)](2) with 1 and 2 equiv of Ph(3)SiSH in hexane afforded dinuclear silanethiolato complexes, [Fe(N(SiMe(3))(2))(mu-SSiPh(3))](2) (1) and [Fe(SSiPh(3))(mu-SSiPh(3))](2) (2), respectively. Various Lewis bases were readily added to 2, generating mononuclear adducts, Fe(SSiPh(3))(2)(L)(2) [L = CH(3)CN (3a), 4-(t)BuC(5)H(4)N (3b), PEt(3) (3c), (LL) = tmeda (3d)]. From the analogous reactions of M[N(SiMe(3))(2)](2) (M = Mn, Co) and [Ni(NPh(2))(2)](2) with Ph(3)SiSH in the presence of TMEDA, the corresponding silanethiolato complexes, M(SSiPh(3))(2)(tmeda) [M = Mn (4), Co (5), Ni (6)], were isolated. Treatment of 3a with (PPh(4))(2)[MoS(4)] or (NEt(4))(2)[FeCl(4)] resulted in formation of a linear trinuclear Fe-Mo-Fe cluster (PPh(4))(2)[MoS(4)(Fe(SSiPh(3))(2))(2)] (7) or a dinuclear complex (NEt(4))(2)[Fe(2)(SSiPh(3))(2)Cl(4)] (8). On the other hand, the reaction of 3a with [Cu(CH(3)CN)(4)](PF(6)) gave a cyclic tetranuclear copper cluster Cu(4)(SSiPh(3))(4) (9), where silanethiolato ligands were transferred from iron to copper. Silicon-sulfur bond cleavage was found to occur when the cobalt complex 5 was treated with (NBu(4))F in THF, and a cobalt-sulfido cluster Co(6)(mu(3)-S)(8)(PPh(3))(6) (10) was isolated upon addition of PPh(3) to the reaction system. The silanethiolato complexes reported here are expected to serve as convenient precursors for sulfido cluster synthesis.     

Synthesis and characterization of iron(II) and ruthenium(II) hydrido hydrazine complexes

Treatment of trans-[MHCl(dmpe)(2)] (M = Fe, Ru) with hydrazine afforded the hydrido hydrazine complexes cis- and trans-[MH(N(2)H(4))(dmpe)(2)](+) which have been characterized by NMR spectroscopy ((1)H, (31)P, and (15)N). Both cis and trans isomers of the Fe complex and the trans isomer of the Ru complex were characterized by X-ray crystallography. Reactions with acid and base afforded a range of N(2)H(x) complexes, including several unstable hydrido hydrazido complexes.     

Synthesis,characterization and biomimetic oxygenations of manganese(II), iron(III) and copper(II) pyridyl hydrazone complexes

The preparation and characterization of MnII, FeIII and CuII complexes of three tridentate pyridyl hydrazones are reported. The ligands were prepared via Schiff base condensation of 6-chloro-2-hydrazopyridine with alpha-formyl-(L1), alpha-acetyl-(L2), or alpha-benzoyl-(L3) pyridine. The structural characterization of the compounds prepared was based on elemental analyses, electrical conductance and magnetic moment measurements, 1H-n.m.r., i.r., u.v.-vis. and e.s.r spectroscopic methods. The overall structure and reactivity of the metal chelates critically depend on the ligand substituents within the carbonyl moiety. Octahedral and tetrahedral monomeric species were proposed for MnII complexes, and an octahedral environment for the FeIII complexes. Regarding the copper(II) complexes, a monomeric square-planar and a dimeric structure with a chloride bridge in square-pyramidal geometry were suggested. In the presence of molecular oxygen, MnII and CuII complexes catalyse the oxidative transformation of catechol (benzene-1,2-diol) to the corresponding o-benzoquinone. Iron(III) complexes catalyse the aerobic oxidation of catechol to the intradiol cleavage product. The catalytic activity has been correlated with the Lewis acidity of the metal centres created according to the nature of the ligand substituents. The probable mechanistic implications of the catalysed oxidation reactions are discussed. This revised version was published online in June 2006 with corrections to the Cover Date.     

2,2′-bipyridylamine complexes of silver(I), zinc(II) and cadmium (II) nitrates

Summary Coordination compounds formed by the interaction of 2,2bipyridylamine with silver(I), zinc(II) and cadmium(II) nitrates have been prepared and characterized by molecular conductance and i.r. spectral measurements down to 200 cm^–1 in the solid state. Silver([) and zinc(II) nitrates formed 1 : 1 complexes, while cadmium(II) nitrate gave a 1 : 2 complex with 2,2-bipyridylamine. Molar conductivities indicate that the silver complex behaves as a uniunivalent electrolyte while the zinc(II) and cadmium(II) complexes behave as unidivalent electrolytes in methanol and dimethylformamide. All the complexes are considered monomeric with terminally bonded monodentate nitrato groups. Four-coordinate tetrahedral, three-coordinate planar and six-coordinate octahedral stereo chemistries are suggested for the zinc(II), silver(l) and cadmium(II) nitrate complexes with 2,2-bipyridylamine, respectively.     

Synthesis,characterization and susceptibility of bacteria against Sulfamethoxydiazine complexes of copper(II), zinc(II), nickel(II), cadmium(II), chromium(III) and iron(III)

Complexes of sulfamethoxydiazine with Cu(II), Zn(II), Ni(II), Cd(II), Cr(III) and Fe(III) have been synthesized and characterized on the basis of conductivity measurements, elemental analyses, UV, IR, ¹H?NMR and thermal studies. It is shown that sulfamethoxydiazine behaves as a bidentate ligand, binding the metal ion through the sulfonyl oxygen and sulfonamide nitrogen. In vitro susceptibility tests of these complexes against Escherichia coli, Bacillus subtilis, Proteus vulgaris and Staphylococcus aureus were carried out. The results show that the antibacterial activities of the complexes of Zn(II), Cu(II), Cr(III) and Fe(III) are, in general, stronger than that of sulfamethoxydiazine, while the complexes of Cd(II) and Ni(II) are less active.     

Synthesis and characterization of silver(I), gold(I), and gold(III) complexes bearing a bis-dialkylamino functionalized N-heterocyclic carbene

Bis-1,3-[2-(diisopropylamino)ethyl]-imidazolium chloride, 1, has been prepared and used as a precursor for the synthesis of the corresponding silver(I) chloride complex 2. The single crystal structure analysis reveals that the complex dimerizes in the solid state. Transmetalation of 2 with (tht)AuBr (tht = tetrahydrothiophene) yields the (NHC)Au(I)Br complex 3. By treatment with bromine it is oxidized to (NHC)AuBr₃, 4, which is obtained as a yellow, microcrystalline powder. The UV-vis spectra of 4 are dependent on the pH-value and suggest a square-pyramidal structure in solution.     

Synthesis and spectroscopic characterization of Zn(II), Cd(II), and Hg(II) ciprofloxacin complexes

Ciprofloxacin metal co mplexes with general for mula [M(CPF)₂]X₂·nH₂O [M = Zn(II), Cd(II), and Hg(II)] have been synthesised and characterized using elemental analysis (CHN), spectroscopic (UV-Vis, IR, MS, and ¹H NMR) and ther mogravimetric (TG and DTA) data. Using the Coats-Redfern and Horowitz-Metzeger methods, kinetic analysis of the thermogravimetric data had been performed.     

Synthesis and chemical characterization of biologically important complexes of vanillin thiosemicarbazone with manganese(II), iron(II), cobalt(II), nickel(II), copper(II), zinc(II), cadmium(II), and mercury(II)

Summary Vanillin thiosemicarbazone (VTSC) has been used to isolate the complexes of the types [M(VTSC)₂(H₂O)₂]X₂ (M=Mn^II, Fe^II, Co^II, or Ni^II and X=Cl) and [M(VTSC)X₂]H₂O (M=Cu^II, Zn^II, Cd^II or Hg^II and X=Cl). Probable structures of these complexes are suggested on the basis of elemental analysis, molar conductance, magnetic moment and electronic and i.r. spectral data. The fungicidal activity of VTSC and the isolated complexes has been evaluated on pathogenic fungi,Alternaria (Sp.),Paecilomyces (Sp.) andPestalotia (Sp.).On leave from the University of Myosore.     

Synthesis,characterization and catalytic studies of iron(III), cobalt(II), nickel(II) and copper(II) complexes containing triphenylphosphine and β-diketones

A series of new β-diketonato complexes have been synthesized from the reactions of iron(III), cobalt(II), nickel(II) and copper(II) Ph₃P complexes with β-diketones (acetylacetone, benzoylacetone and dibenzoylmethane). All the complexes have been characterized by elemental analyses, spectral studies (i.r., electronic., magnetic., e.p.r., ¹H-n.m.r.) and cyclic voltammetry. The new complexes have been used as catalysts for aromatic coupling and oxidation reactions. Higher catalytic activity has been observed for the nickel(II) complexes compared to the other complexes.     

Synthesis and characterization of cationic heteronuclear complexes of platinum(II) and silver( I) bridged by alkynyl ligands

The dialkynyl complexes cis-[Pt(C CR)₂L₂] [R = Ph, L₂ = 2PPh₃, 2PEt₃, dppe (dppe = 1,2-bis(diphenylphosphino)ethane]; R ---^tBu, L₂ = 2PPh₃, dppe) react with silver perchlorate in a molar ratio 1:0.5 to give platinum-silver perchlorate salts of the type [Pt₂ Ag(C CR)₄L₄](ClO₄) in excellent yield. The X-ray crystal structure of [Pt₂Ag(C = CPh)₄(PPh₃)₄](ClO₄) 1 shows that the cation is formed by two nearly orthogonal cis-[Pt(C CPh)₂(PPh₃)₂] units connected through a silver cation which is unsymmetrically π-bonded to all four acetylene fragments. Similar reactions of cis-[Pt(C CR)₂L₂] with one equivalent of AgClO₄ afford cationic complexes of general formula [PtAg(C CR)₂L₂](ClO₄), which are believed to be salts, [Pt₂Ag₂(C CR)₄L₄](ClO₄)₂.     

Structure and dynamics of tetrakis(thiophosphinato)resorcinarene complexes of silver(I), gold(I), and palladium(II)

The coordination chemistry of the tetrakis(thiophosphinato)resorcinarene sulfur-donor ligands [(C6H2CH{CH2CH2Ph})4{OC(O)R}4{OP(=S)Ph2}4] (L), where R = OCH2Ph, 4-C6H4CH3, C6H11, C4H3S, or OCH2CCH, is reported. Both silver(I) and gold(I) form cationic complexes of the type [LM2]2+, in which the ligand acts as a bis(chelate) in forming complexes with linear S-M-S (M = Ag or Au) stereochemistry. Gold(I) also forms the unusual complex [L(AuCl)2][LAu2]2+, which forms a supramolecular polymer through intermolecular aurophilic attractions. Palladium(II) forms the complex [LPd2Cl2(mu-Cl)2], in which the dipalladium(II) unit extends the natural bowl structure of the resorcinarene. The solid-state and solution conformations of the complexes, as determined by X-ray structure determination and NMR spectroscopy, respectively, are similar, but several complexes were found to exhibit dynamic behavior in solution, involving either conformational mobility of the resorcinarene unit or intermolecular ligand exchange.     

Synthesis and characterization of Ni(II), Zn(II), and Cd(II) complexes with dithiophosphonate derivatives

Ammonium salts of p-methoxyphenyldithiophosphonic acid O-alkyl esters (H₃CO-C₆H₄-(RO)P(S)S⁻NH ₄ ⁺ ; R = C₂H₅,-CH₂CH₂CH₂CH₂-, and cyclopentyl) and their complexes with Ni²⁺, Cd²⁺, and Zn²⁺ were prepared. 2,4-Bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane-2,4-disulfide, the so-called Lawesson reagent, was treated with the corresponding alcohol to give the O-alkyl ester of the acid. Dry NH₃ was then purged through the solution of this ester to form the ammonium salt of the O-alkyl dithiophosphonic acids. Nickel complexes of these ligands were formed in acetic acid, while zinc and cadmium complexes were formed in water and an ethanol medium, respectively. The geometry of the coordinated atoms was square planar with Ni²⁺ and tetrahedral with Zn²⁺ and Cd²⁺. Using an alkanediol, two dithiophosphonic acids were bridged, thus forming a ligand with four S atoms for coordination. The zinc and cadmium complexes of these tetradentate ligands were also synthesized. The text was submitted by the authors in English.     

Synthesis and crystal structure characterization of iron(II), cobalt(II) and nickel(II) complexes with 1,3-bis(2-pyridylmethylthio)propane

Three new mononuclear complexes of nitrogen–sulfur donor sets, formulated as [Fe^II(L)Cl₂] (1), [Co^II(L)Cl₂] (2) and [Ni^II(L)Cl₂] (3) where L = 1,3-bis(2-pyridylmethylthio)propane, were synthesized and isolated in their pure form. All the complexes were characterized by physicochemical and spectroscopic methods. The solid state structures of complexes 1 and 3 have been established by single crystal X-ray crystallography. The structural analysis evidences isomorphous crystals with the metal ion in a distorted octahedral geometry that comprises NSSN ligand donors with trans located pyridine rings and chlorides in cis positions. In dimethylformamide solution, the complexes were found to exhibit Fe^II/Fe^III, Co^II/Co^III and Ni^II/Ni^III quasi-reversible redox couples in cyclic voltammograms with E_1/2 values (versus Ag/AgCl at 298 K) of +0.295, +0.795 and +0.745 V for 1, 2 and 3, respectively.