Synthesis and spectral studies ofo-hydroxyacetophenone (N-benzoyl)glycyl hydrazone and some of its lanthanide(III) complexes

Summary o-Hydroxyacetophenone (N-benzoyl)glycyl hydrazone (o-HABzGH) has been characterized by i.r.,¹H n.m.r.,¹³C n.m.r. and mass spectral studies, and its complexes of the types [Ln(o-HABzGH)Cl₂(H₂O)₂]Cl and [Ln(o-HABzGH–2H)OH(H₂O)₃], where Ln=La, Pr, Nd, Sm and Eu, have been synthesized. The structures of the complexes have been studied by conductance, magnetic, electronic, i.r.,¹H n.m.r. and¹³C n.m.r. spectral techniques. The hypersensitive bands of the electronic spectra suggest coordination numbers six and seven around Nd^III in its adduct and neutral complexes respectively. I.r. and n.m.r. spectral data suggest a neutral bidentate behaviour for the ligand in the adducts and a dinegative tridentate nature in the neutral complexes.     

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

Summary Cu^II 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 Cu^II complexes show either modest or no growth inhibitory activity against Paecilomyces variotii. Some of the thiosemicarbazones demonstrated significant activity against tumour cell strains.     

Ruthenium(II) complexes containing bidentate Schiff bases and their antifungal activity

The reactions of ruthenium(II) complexes, [RuHCl(CO)(PPh₃)₂(B)] [B = PPh₃, pyridine (py) or piperidine (pip)], with bidentate Schiff base ligands derived by condensing salicylaldehyde with aniline, o-, m- or p-toluidine have been carried out. The products were characterised by analytical, i.r., electronic, ¹H-n.m.r. and ³¹P-n.m.r. spectral studies and are formulated as [RuCl(CO)(L)(PPh₃)(B)] (L = Schiff base anion; B = PPh₃, py or pip). An octahedral structure has been tentatively proposed for the new complexes. The Schiff bases and the new complexes were tested in vitro to evaluate their activity against the fungus Aspergillus flavus.     

Ruthenium(II) ligated to tetradentate diaminodithioethers: synthesis,characterisation and electrochemistry

Ruthenium(II) complexes containing two tetradentate ligands, 1,2-bis(o-aminophenylthio)ethane (L¹) and 1,2-(oaminophenylthio)xylene (L²), have been prepared. The complexes, which are of the type Ru(L)Cl₂ [L = L¹ (1);/L² (2)], [Ru(L)(PPh₃)Cl]Cl [L = L¹ (3); L² (4)] and [Ru(L)(bpy)](PF₆)₂ [L = L¹ (5);/L² (6)], were characterised by elemental analysis, i.r., u.v.-vis. and n.m.r. spectroscopy and their electrochemical behaviour has been examined by cyclic voltammetry using a glassy carbon working electrode and an Ag/AgCl electrode as the reference electrode. This revised version was published online in June 2006 with corrections to the Cover Date.     

Octanuclear Palladacycles with B(3)–H Bond Activation of o-Carborane†

Herein, we describe the synthesis of a carborane-supported octanuclear palladacycle complex, Pd₈(o-C₂B₁₀H₁₀CS₂CH₃)₄Cl₄(CH₃CN)₄ (complex 1 ), with B(3)–H activations on o-carborane ligand. The substitution reaction of 1 has been explored, and three of its substituted complexes Pd₈(o-C₂B₁₀H₁₀CS₂CH₃)₄Cl₄(L)₄ (L = ^tBuNC, 2 ; L = C₅H₅N, 3 ; L = C₄H₈S, 4 ) have been synthesized. The m- and p-carborane disubstituted ligands m- and p-C₂B₁₀H₁₀(CS₂CH₃)₂ (ligands 5 and 6 ) as well as their B—H activated carborane complexes [m-C₂B₁₀H₉(CS₂CH₃)₂PdCl] ( 7 ) and [p-C₂B₁₀H₈(CS₂CH₃)₂][PdCl(^tBuNC)]₂ ( 8 ) have also been synthesized by the similar method. All of these complexes have been characterized, including X-ray single crystal diffraction, NMR spectroscopy, IR spectroscopy and elemental analysis methods.      

Neutral,cationic and dicationic seven-coordinate complexes of molybdenum(II) and tungsten(II) containing mono- and bidentate nitrogen donor ligands

Summary The seven-coordinate complexes [MI₂(CO)₃(NCMe)₂] (M=Mo or W) react with two equivalents of L(L=py, 4Me-py, 3Cl-py or 3Br-py) or one equivalent of NN {NN=2,2-bipyridine(bipy), 1,10-phenanthroline(phen), 5,6-dimethyl-1, 10-phenanthroline (5,6-Me₂-1, 10-phen), 5-Nitro-1, 10-phenanthroline (5-NO₂-1, 10-phen) and C₆H₄(o-NH₂)₂ (o-diam) (for M=Mo only)} in CH₂Cl₂ at room temperature to give the substituted products [MI₂(CO)₃L₂] or [MI₂(CO)₃(NN)] (1–17) in high yield. The compounds [MI₂(CO)₃(NCMe)₂] react with two equivalents of NN (for M=W, NN=bipy; for M=Mo, NN=phen) to give the dicationic salts [M(CO)₃(NN)₂]2I(18–19). The compounds [MI₂(CO)₃(NCMe)₂] (M=Mo or W) react with two equivalents of 5,6-Me₂-1, 10-phen to yield the monocationic dicarbonyl compounds [MI(CO)₂(5,6-Me₂-phen)₂]I (20 and21). The dicationic mixed ligand complexes [M(CO)₃(bipy)(5,6-Me₂-phen)]2I (22 and23) are prepared by reacting [MI₂(CO)₃(NCMe)₂] with one equivalent of bipy, followed by anin situ reaction with 5,6-Me₂-1, 10-phen to afford the products22 and23. The complexes (1–23) described in this paper have been characterised by elemental analysis (C, H and N), i.r. spectroscopy and, in selected cases,¹Hn.m.r. spectroscopy. Magnetic susceptibility measurements show the compounds to be diamagnetic.     

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

Summary Cu^II 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.     

Oxocation complexes,Part X. Oxomolybdenum(V) and dioxomolybdenum(VI) complexes with tri- and tetra-dentate Schiff bases

Summary Many new oxomolybdenum(V) and dioxomolybdenum(VI) complexes have been synthesized with tri- and tetradentate Schiff bases derived by the condensation of salicylaldehyde, thiosalicylaldehyde,o-hydroxyacetophenone, 3-carboxysalicyclaldehyde or acetylacetone with aminoalcohols, polymethylenediamines ando-phenylenediamines. Mononuclear oxothiolato Schiff base complexes of molybdenum(V) have been prepared for the first time. Quadridentate Schiff bases derived from salicylaldehyde and substituted salicylaldehydes ando-phenylenediamine have also been successfully employed to isolate dioxomolybdenum(VI) complexes in the solid state, in which two oxygen atoms of the MoO₂ group arecis- to each other, similar to the situation observed for other dioxomolybdenum(VI) complexes of salicylaldehyde-polymethylenediamine Schiff base ligands.Structures have been determined with the help of elemental analyses, magnetic susceptibilities, molar conductances, i.r., electronic and¹H n.m.r. spectral data.For Part IX, K. Dey, R. K. Maiti and J. K. Bhar,Indian J. Chem., in press.     

ortho-, meta- and para-nitrophenylgold(I) complexes

Treatment of [BzPh₃P][AuCl₂] with [Hg(x-C₆H₄NO₂)₂] (x = o, m, or p) gives anionic gold(I) complexes of the type [BzPh₃P][Au(R)Cl](R = o-, m- or p-C₆H₄NO₂, Bz = C₆H₅CH₂). The chloro ligand in [Au(o-C₆H₄NO₂)Cl]^? can be replaced by bromo or iodo ligands by use of NaBr or NaI. The anions [Au(R)Cl]^? react with neutral monodentate ligands, L, to give neutral mononuclear complexes [Au(R)L] (R = o-C₆H₄NO₂, L = PPh₃, AsPh₃; R = m-C₆H₄NO₂, L = PPh₃) and with 1,2-bis(diphenylphosphino)ethane (dpe) to give [Au₂(R)₂(dpe)] (R = o-C₆H₄NO₂). The corresponding [Au(p-C₆H₄NO₂)Cl]^? reacts with PPh₃ or AsPh₃ to give mixtures containing [AuClL]. The anionic ortho-nitrophenylgold(I) complex is much more stable than its meta- or para-nitrophenyl isomers. These are thought to be the first reports of nitrophenylgold(I) complexes.     

Synthesis and characterization of palladium(II) complexes of some tellurium heterocycles

Summary A series of square planar complexes of the type [PdX₂L₂] where X=Cl, Br, I; L=telluracyclopentane (tcp), telluracyclohexane (tch) or benzotelluracyclopentane (btp) have been synthesised. The complexes were characterised by far-i.r., n.m.r. and u.v.-vis. spectroscopy. The data implytrans-geometries except for the complex [PdCl₂(tch)₂] where a mixture ofcis- andtrans-isomers is obtained.     

Novel metal-based antimicrobial agents of copper(II) complexes: Synthesis,spectral characterization and DNA interaction study

Few novel mixed ligand copper(II) complexes of the type [Cu(L)(Cl)₂(H₂O)], [Cu(L)₂]Cl₂, [Cu(L)L¹] and [Cu(L)(phen)H₂O]Cl₂ (where L is the ligand obtained from the condensation of N-(2-aminoethyl)-1,3-propanediamine with m-nitrobenzaldehyde (L_a)/o-chlorobenzaldehyde (L_b)/benzaldehyde (L_c)/p-methoxybenzaldehyde (L_d)/p-hydroxybenzaldehyde (L_e)/furfuraldehyde (L_f)/pyrrole-2-carboxaldehyde (L_g); L¹ is another ligand obtained from the condensation of anthranilic acid with salicyaldehyde; phen = 1,10-phenanthroline) have been synthesized and characterized by the spectral and analytical techniques. From these data, it is found that the ligands adopt distorted octahedral geometry on metalation with Cu(II) ion. The XRD data indicate that the complexes are polycrystalline with nanosized grains. The SEM images of [Cu(L_a)phen(H₂O)]Cl₂ and [Cu(L_f)₂]Cl₂ complexes show that they have leaf and cauliflower like morphology. The in vitro biological screening effects of the investigated compounds have been tested against the bacteria such as Escherichia coli, Klebsiella pneumoniae, Salmonella typhi, Pseudomonas aeruginosa and Staphylococcus aureus and fungi such as Aspergillus niger, Rhizopus stolonifer, Aspergillus flavus, Rhizoctonia bataicola and Candida albicans by the well diffusion method. A comparative study of MIC values of the Schiff base ligands and their complexes indicates that the complexes exhibit higher antimicrobial activity than the free ligands. An electrochemical study of the copper complexes containing electron withdrawing substituted ligands reveals that they prefer to bind to DNA in Cu(II) rather than Cu(I) oxidation state.     

Ruthenium(II) carbonyl complexes with tridentate Schiff bases and their antibacterial activity

The products obtained by reacting ruthenium (II) complexes [RuHCl(CO)(PPh₃)₂(B)] [B = PPh₃, pyridine (py) or piperidine (pip)] with tridentate Schiff base ligands derived by condensing salicylaldehyde or o-vanillin with o-aminophenol and o-aminothiophenol, have been characterised by analytical, i.r., electronic, ¹H-n.m.r. and ³¹P-n.m.r. spectral studies and formulated as [Ru(L)(CO)(PPh₃)(B)] (L = bifunctional tridentate Schiff base anion, B = PPh₃, py or pip). An octahedral structure has been tentatively proposed for the new complexes. Some have been tested for the in vitro growth inhibitory activity against bacteria Escherichia coli, Bacillus sp. and Pseudomonas sp.     

Synthetic and structural studies of some trivalent lanthanide metal complexes of o -hydroxyacetophenone (N-benzoyl)glycyl hydrazone

o-Hydroxyacetophenone (N-benzoyl)glycyl hydrazone (o-HABzGH) forms complexes of the types [M(o-HABzGH)Cl₂(H₂O)₂]Cl and [M(o-HABzGH-2H)OH(H₂O)₂], where M = Y(III), Gd(III), Tb(III) and Dy(III). The complexes have been characterized by elemental analyses, molar conductance, magnetic susceptibility, infrared, electronic,¹H NMR and¹³C NMR spectral techniques. The nephelauxetic ratio (β), covalency (δ), bonding parameter (b ^1/2) and angular overlap parameter (η) have been calculated from Dy(III) complexes. Infrared and NMR spectral studies show thato-HABzGH acts as a neutral bidentate ligand in the adduct complexes and as a dinegative tridentate one in the neutral complexes. A coordination number of six has been proposed for the metal ion in all the complexes.     

Complexes of Copper(II) Aryl Carboxylates with Picoline N-Oxides

Copper(II) aryl carboxylates on interaction with 2-picoline N-Oxide (2-picNO), 3-picoline N-Oxide (3-picNO) and 4-picoline N-Oxide (4-picNO) in acetone or ethyl acetate yield 1:1 adducts. These are regarded as binuclear bridged complexes of composition Cu₂(RC₆H₄COO)₂L₂ where R is o-, m-, p-CH₂; o-, m-Cl: o-NO₂; m-, p-CH₂O; and L is 2-, 3-, and 4-picNO ligand. With 4-picNO some 1:2 adducts have also been obtained.     

A new (E,E)-dioxime and its mono and heterotrinuclear complexes containing an 18-membered dithiatetraazamacrocycle

The novel (E,E)-dioxime, 5,6:ll,12:17,18-tribenzo-2,3-bis(hydroxyimino)-7,16-dithia-9, 14-dioxo-l,4,10,13-tetraazacyclooctadecane (H₂L) has been synthesized by reacting (E,E)-dichloroglyoxime (2) with 2,3:8,9:14,15-tribenzo-4,13-di-thia-6,11-dioxa-l,7,10,16-tetraazahexzadecane (3), prepared by the reaction of N,N-bis(chloroacetyl)-1, 2-phenylene-diamine (1) with 2-aminothiophenol. Mononuclear complexes (4, 5) of this ligand have been synthesized by reacting the vic-dioxime (H₂L) with K₂PtCl₄ and NiCl₂ · 6H₂O, respectively. Heterotrinuclear complexes (6)and(7) have been prepared by the reaction of (4) and (5) mononuclear complexes with [Cu(MeCN)₄]PF₆. The structures of the vic-dioxime and its mono and trinuclear complexes were identified by elemental analysis, ¹H- and ¹³C-n.m.r, i.r. and m.s. data.     

Synthesis and physico-chemical studies of novel mixed-ligand cyanonitrosyl {CrNO}5 complexes of chromium with benzyl-, benzoyl- and acetyl-pyridines

Summary Novel mixed-ligand cyanonitrosyl complexes of chromium(I), [Cr(NO)(CN)₂(L)₂(H₂O)], (where L=2-, 3-, or 4-benzylpyridine, 2-(4-chlorobenzyl)pyridine, 2-, 3-, or 4-benzoylpyridine, 3-(4-methylbenzoyl)pyridine, or 2-, 3-, or 4-acetylpyridine) have been prepared by the interaction of potassium pentacyanonitrosylchromate(I) monohydrate, K₃[Cr(NO)(CN)₅]·H₂O with L. The complexes, characterized by elemental analyses, magnetic measurements, e.s.r. and i.r. spectral studies, contain chromium(I) in a low-spind ⁵-configuration. An octahedral structure, where CN istrans to CN, L istrans to L, and NO istrans to water is proposed for all the complexesEnemark and Feltham⁽¹⁾ have proposed circumventing the problem of the non-innocent nature of the nitrosyl ligand by considering nitrosyls as containing the {MNO} ⁿ group, wheren is the number of electrons of M, plus the number of electrons in the ^*-orbital of the NO (or more convenientlyn is the number of d-electrons if nitrosyl is regarded as being coordinated as NO⁺)     

Palladium(II) and platinum(II) complexes with N-substituted methionines

Summary As an approach to systems containing methionine residues, 3-acetyl-4-hydroxy-6-methyl-2H-pyran-2-one (HDh, dehydroacetic acid) was treated with L-methionine (MetH) or L-methionine methylester (MetM). By condensation at the acyl group and transfer of the phenolic hydrogen on the nitrogen atom, the related ligands DhMetH and DhMetM, were isolated, and form complexes of formula [MX₂(L)₂](M = Pd or Pt, L = DhMetM, X = Cl, Br or I; L = DhMetH, X = Cl or Br) and [MI₂(DhMetH)] with palladium and platinum dihalides. The reaction of the DhMetK carboxylate with MCl₂ in various media is discussed. Ligands and complexes were characterized by i.r. and n.m.r. (¹H and¹³C) spectroscopy and, in some cases, by thermogravimetric measurements. The ligands behave as monodentate sulphur donors, the 12 complexes showing atrans geometry except for [PtCl₂(DhMetH)₂], which is probably a mixture ofcis andtrans isomers.     

Complexes of cobalt(II) aryl carboxylates with quinoline and isoquinoline

Summary Several new complexes of cobalt(II) aryl carboxylates Co(O₂CC₆H₄R)₂ (R =o-Me;o,m-Cl:o,m-NO₂ andm-MeO) have been prepared by refluxing an ethanolic solution of the respective cobalt(II) aryl carboxylate with quinoline (Q) and isoquinoline (IQ). The quinoline complexes are green or purple while isoquinoline complexes are pink to reddish pink. All are neutral and soluble in common organic solvents. Analytical data indicate that quinoline complexes are of 1:1 stoichiometry. Magnetic and spectral studies show them to possess the usual copper(II) acetate monohydrate type dimeric carboxylate bridged structures. formulated as Co₂(O₂CC₆H₄R)₄Q₂, in which cobalt(II) is in a square pyramidal geometry. By contrast, isoquinoline yields monomeric bisamine complexes oftrans-octahedral configuration containing bidentate chelating carboxylate groups.     

Characterization and electrochemical studies of molybdenum(VI) dioxodialkylbipyridyl complexes. X-ray crystal structure of MoO2(o-MeC6H4CH2)2(bipy)

Summary New Mo^VI-dioxodialkyl complexes, MoO₂R₂(bipy), R = CH₂CH₂Ph and p-MeC₆H₄CH₂; bipy = 2,2-bipyridine, have been synthesized. The i.r. and the ¹H-n.m.r. spectra of these complexes are noted. The structure of MoO₂(o-MeC₆H₄CH₂)₂(bipy) was determined by X-ray analysis. Significant differences in the redox characteristics of these dioxodialkylcompounds are reflected in the contrasting patterns: whereas reduction of MoO₂-(CH₂CH₂Ph) ₂(bipy) is a reversible one-electron process, under similar conditions MoO₂(p-MeC₆H₄CH₂)₂(bipy) and MoO₂(o-MeC₆H₄CH₂)₂(bipy) are reduced irreversibly. Similarly, solutions of MoO₂(CH₂CH₂Ph)₂(bipy) remain unchanged but oxygenated organic products are formed from MoO₂(p-MeC₆H₄CH₂)₂(bipy) and MoO₂ (o-MeC₆H₄CH₂)₂(bipy).     

Synthesis,characterization and antimicrobial activity of cobalt(II), nickel(II)and copper(II) complexes with new asymmetrical Schiff base ligands derived from 7-formyanil-substituted diamine-sulphoxine and acetylacetone

Asymmetric 7-formyanil-substituted-imino-4-(4-methyl-2-butanone)-8-hydroxyquinoline-5-sulphonic acid (Schiff bases), react with Co^II, Ni^II and Cu^II ions to give 1:2, 1:1 and 2:1 complexes as established by conductometric titrations in 1:1 DMF:H₂O. The complexes were investigated by elemental analyses, molecular weight determinations, molar conductance, magnetic moments, thermal analysis, i.r., u.v.–vis. and e.s.r. spectra. The complexes have an octahedral crystal structure and general formula [ML·(OH₂)₂], where M^II = Co, Ni and Cu, and L = Na[7—X—HL], (—X— = (CH₂)₂, (CH₂)₃, p-C₆H₄, o-C₆H₄). Antimicrobial activity of these new ligands and their transition metal complexes has been screened in vitro on common fungi and bacteria.