Showing papers in "Transition Metal Chemistry in 1978"

Sulphur dioxide complexes of the platinum metals

Abstract: The structural, chemical and theoretical aspects of the coordination chemistry of sulphur dioxide complexes of the platinum metals have been reviewed. A detailed evaluation of the analogy between nitric oxide and sulphur dioxide ligands has been made, and it has been concluded that although the structural properties of complexes of these ligands are closely related, their oxidative-addition and oxidation reactions differ in many important respects.

The infrared spectra (3500-140 cm−1) of the 2,2'-bipyridine, 2-aminomethylpyridine and ethylenediamine adducts and the sodium tris-compounds of cobalt(II), nickel(II) and zinc(II) acetylacetonates

Abstract: The M(acac)2B and NaM(acac)3 complexes (M = Coll, Nill orZnll; acac=acetylacetonateanion; B=2,2′=bipyridine, 2-aminomethylpyridine or ethylenediamine) have been prepared and their i.r. spectra determined over the 3500-140 cm−1 range. Complete band assignments have been made on a comparative basis, with the effects of ligand substitution and metal ion substitution being considered. Bands in the i.r. spectra of the complexes which are associated with 2,2′-bipyridine, 2-aminomethylpyridine and ethylenediamine arc in excellent agreement with values previously established for these ligand and metal-ligand vibrations, in related complexes. Band assignments for acetylacetonate anion and metal-acetylacetonate vibrations substantiate those made in certain of the previously published papers. The method of assignment adopted has allowed the complete assignment of bands in the i.r. spectra of the metal complexes.

Stabilization of uranium(IV) in heteropoly anions

Abstract: The heteropoly anions [UIVMo12O42]8−(UMo12), [UIVW10O36]8− (UW10), [UIV(PW11O39)2]10 [U(PW11)2] and [UIV(SiW11O39)2]12 [U(SiW11)2] were examined by cyclic voltammetry on a wax-impregnated carbon electrode. Reversible one-electron oxidations were observed for UMo12 (E = +0.91 V vs see at pH = ca. 0), U(PW11 )2 (E = +0.60 V at pH 4.4) and U(SiW11)2 (E = +0.19 V at pH 4.4). No oxidation of UW10 was detected at potentials prior to oxygen discharge (ca. +0.9 V at pH 7). Controlled potential oxidation of aqueous solutions of UMo12 gave unstable solutions of [UVMo12O42]7−. Oxidation of U(PW11)2 was achieved in aqueous and nonaqueous (acetonitrile, propylene carbonate) solution. The electronic spectra of UVMo12 and UV(PW11)2 are reported and are discussed in terms of UO12 (/y) and UO8 (D4d) chromophores respectively. Possibilities for geometrical and optical isomers of U(XW 11)2 anions are considered. Solutions of brucinium salts of U(PWI I)2 and UW10 in dimethyl formamide show induced Cotton effects at wavelengths corresponding to the f-f transitions of UIV. The voltammograms of UMo12, ThMo12 and CeMo12 show an irreversible twelve-electron reduction at -0.25 V. The pale brown reduced solutions cannot be reoxidized to the original heteropoly anions.

Copper(I) complexes of neutral, deprotonated and protonated 4,6-dimethylpyrimidine-2 (1H)-thione

Abstract: The following copper(I) complexes of 4,6-dimethylpyrimidine-2(1H)-thione (HL), its protonated cation (H2L+) and deprotonated anion (L−) have been prepared: CuL, Cu(HL)X (X = Cl, Br or I), Cu(HL)2X (X = C1 or Br), Cu2(HL)3Br2, Cu(H2L)X2 (X = Cl or Br), Cu3(HL)2LA2 (A = ClO4 or BF4 ). The i.r. spectra show that in all the HL and L− complexes and in the Cu(H2L)Br2 complex, the ligands are S, N coordinated to the metal ion, while in Cu(H2L)Cl2 only the thiocarbonylic sulphur is coordinated, probably bridging two copper(I) atoms. Thev(CuN) (288–317 cm−1 ) andv(CuS) (191–225 cm−1 ) have uniform frequency values in all the complexes. The halide ions are, in all their complexes, wholly or in part coordinated giving twov(CuX) bands which may indicate an asymmetrical Cu-X ⋯Cu halide bridging bond.

Sulphoxide complexes of ruthenium

Abstract: Compounds of the type RuL4−nX2+n where L = dimethyl sulphoxide (DMSO), tetramethylene sulphoxide (TMSO) and X = Cl, Br or I for n = 0 and L = di-n-propyl sulphoxide (n-Pr2SO) and di-n-butyl sulphoxide (n-Bu2SO) X = Cl or Br for n = 1 and also Ru(DMSO)6Br3 have been prepared and studied The important ir bands of all compounds together with their electronic spectra and the thermograms of some of them are discussed In order to interpret the ir data, the corresponding deuteriated (DMSO-d6) analogues have also been prepared In the majority of the compounds of the type RuL4X2 the sulphoxide ligands are bonded through the sulphur atom; in a few cases, bonding through both S- and O-donor sites has been found A mixed type of bonding is also observed in Ru(DMSO)6Br3 and in RuL3X3

Synthesis and characterization of rhodium(III), iridium(III), ruthenium(III) and osmium(III) complexes containing sterically hindered heterocyclic ligands

Abstract: Some thiazolidine-2-thione and thiomorpholin-3-one complexes of rhodium(lll), iridium(III), ruthenium(III) and osmium(III) have been prepared and characterized by chemical analysis, conductivity measurements, room temperature magnetic moment studies, electronic, i.r. and far i.r. spectra and n.m.r. measurements. From the magnetic properties it was concluded that the above ligands form low-spin complexes with all the metal ions. The position and multiplicity of the metal-halogen stretching modes in the far-i.r. region have been extensively investigated and discussed; the results are particularly useful in distinguishing between themer- andfac-isomers in the octahedral compounds of the ML3 X3 type. The wavelengths of the principal electronic absorption peaks have been accounted for quantitatively in terms of the crystal field theory and the various parameters have been calculated. On the basis of the electronic spectra a trigonal bipyramidal geometry,D3h, has been established for the Ru(tm)2Cl3 complex; the Ir(rm)2Cl3 · H2O complex has also been prepared. It is penta-coordinated and a trigonal bipyramidal environment is suggested for the iridium(III) ion.

Nickel(II) and copper(II) complexes of 2,5-dimethyl-1,3,4-thiadiazole

Abstract: Nickel(II) and copper(II) complexes of 2,5-dimethyl-1,3,4-thiadiazole Ni(DTZ)X2 (X = Cl or Br) and M(DTZ)2X2 (M = Ni, X = 1 or N03; M = Cu, X = Cl, Br or NO3) have been prepared. The i.r. spectra show that in all the complexes the ligand is N,N- or N-bonded to the metal while the sulfur atom does not participate in coordination, and that the halide ions are coordinated forming terminal M-X bonds. The NO 3 - group is coordinated in both the nitrato complexes. Magnetic moments of 3.07–3.29 B.M. for the nickel(II) and 1.86–1.92 B.M. for the copper(II) complexes were observed. The Ni(DTZ)X2 complexes have a pseudo-tetrahedral [N2X2] coordination with N,N-bridging ligand molecules. The Ni(DTZ)2X2 and Cu(DTZ)2X2 complexes, with predominantly monodentate ligand, involve six-coordinate metal atoms with strong equatorial [N2X2] bonds and weaker axial bonds.

Behaviour of the thioamido entity in five-membered rings towards copper(II) chloride and bromide

Abstract: The thioamido group, when present as -NH · CS- in five-membered rings, reduces copper(II) to copper(I) in methanol. Evidence for CuL2X2 intermediates are obtained avoiding the reduction by N-alkylation. Crystalline CuL2X2 complexes have been obtained for L =N,N′-dimethyl- andN,N′-diethyl-1,3-imidazolidine-2-thione and X = Cl, Br.

Dimeric tetrahedral complexes of manganese(II) and iron(II) with benzoyl hydrazones

Abstract: Dimeric manganese(II)and iron(II)complexes, (ML)2, derived from benzoyl hydrazones ofo-hydroxyaryl aldehydes and ketones arc described and characterised by elemental analyses and by conductance, molecular weight, magnetic, electronic and i.r. spectral measurements. The dimeric nature of the complexes is revealed by i.r. spectra which show bands atca. 885 Mn2+ and 820 cm−1 Fe2+, characteristic of ring vibrations. The i.r. spectra reveal the terdentate nature of the ligands. The electronic spectra in dimethylformamide are consistent with the tetrahedral nature of the complexes. The appreciable lowering inμ eff is attributed to the presence of exchange interactions between two paramagnetic atomsvia oxygen bridges.

Polymeric coordination compounds of nickel(II), cobalt(II), and zinc(II) with oxalate ions as symmetric tetradentate bridging ligands

Abstract: Coordination compounds having the general formula ML2Ox are described, with Ox = oxalato dianion; M = Ni, Co and Zn; 1 = water and imidazoles. The compounds are characterised by chemical analyses, i.r., far-i.r., Raman, ligand field and e.s.r. spectra. Magnetic susceptibility measurements at low temperatures indicate a polymeric structure of ant i-ferromagnetically coupled M2+ ions.

Reactions of dichlorobis(cyclopentadienyl)titanium (IV) with multidentate Schiff bases

Abstract: Dichlorobis(cyclopentadienyl)titanium(IV), Cp2TiCI2, reacts with bidentate Schiff bases such as salicylideneaniline, salicylidene-o-toluidine, salicylidene-m-toluidine, salicylidene-p-toluidine and 2-hydroxy-l-naphthyl

New pentafluorothiophenoxo derivatives of tin, lead, antimony, bismuth, gold and platinum

Abstract: Salts of the anions [SnX5]−, [SnX4Cl⊥, [SnX3Cl2]−, [SnX3]−, [PbX3]−, [SbX4]−, [SbX3Cl]−, [SbX2Cl2]−, [BiX4]−, [AuCl2]−, [AuX2]−, [AuXCl]−, [AuX4]−, [Au2X6]2− and [PtX4]2−, where X− = C6F5S−, have been isolated and characterised. The neutral SbX3 and BiX3 species, have also been isolated and shown to be pyramidal monomers (19F.n.m.r., i.r., and Raman spectral evidence). Various physical properties of the complexes prepared, as well as their stereochemistries (where these could be ascertained), are similar to those of the known corresponding halogeno compounds of these elements. These results further demonstrate the pseudo-halide nature of the pentafluorothiophenoxide ion.

Bis-η5-cyclopentadienyl and Bis-η5-methylcyclopentadienylN,N-dialkyldithiocarbamato(chloro)titanium(IV) compounds

Abstract: Titanium(IV)N,N-dialkyldithiocarbamates of the type η5-Cp2Ti (S2CNR2)Cl and (η5-MeCp)2Ti(S2CNR2)Cl (R = Me, Et and i-Pr) have been prepared by the reaction of di--cyclopentadienyldichlorotitanium(IV) and bis-n-methylcyclopentadienyldichlorotitanium(IV) with sodium salts of dithiocarbamic acids in refluxing dichloromethane. Molecular weight, conductance and i.r. studies show these complexes to be monomeric nonelectrolytes in which the dithiocarbamate ligands are bidentate. Therefore, pentacoordination may be assigned to titanium(IV) atom in all six complexes. Electronic and proton n.m.r. studies spectra have also been recorded for the complexes.

Complexes of cobalt(II), nickel(II) and copper(II) with 4-amino-3,5-dimethylisoxazole

Abstract: Complexes of the type M(4-ADI)nX2 · mH2O (where 4-ADI = 4-amino-3,5-dimethylisoxazole; n = 1–4; X = Cl, Br, I, SCN, ClO4; m = 1–4) have been studied by i.r. and electronic spectroscopy, magnetic and conductivity measurements. The ligand behaves as a monodentate -NH2 bonded species in monomeric complexes, but as a bridging ligand-NH2 and -N(ring) bonded species in polymeric complexes. All the compounds have an octahedral stereochemistry, except Co(4-ADI)2X2 (X = Cl, Br, I) complexes, which are tetrahedral.

A dimeric high-spin nickel(II) compound with a transition to monomeric tetrahedral nickel(II)

Abstract: The synthesis and characterisation of dichloro[bis(3,5-dimethylpyrazolyl)methane]nickel(II) s described. At ambient temperature the compound is dimeric with chloro-bridged high-spin five-coordinate NiII

Palladium(II) complexes with primary thioamides

Abstract: Palladium(II) complexes of thioacetamide, thiooxamide,N o,N o-dimethylthiooxamide and ethyl thiooxamidate have been prepared and investigated by electronic and i.r. spectroscopy. It is concluded that the ligands always act as monodentate sulphur donors, and that planar [PdL4]X2 (X = Cl, Br or ClO4) compounds are formed. Theν(PdS) frequencies and the ligand field strengths are enhanced by electron donor groups and lowered by electron withdrawing groups.

Thermodynamics of copper(II) dicarboxylate coordination in aqueous solution

Abstract: The association of H+ and Cu2+ with malonate, maleate, succinate and phthalate ions has been investigated both potentiometrically and calorimetrically at 25° and I = 0.1 mol dm−3 (NaClO4). The structures of the complexes existing in aqueous solution are proposed on the basis of thermodynamic data.

Preparation of halogen-modified titanium(II) arene complexes and their electronic spectra

Abstract: Complexes of overall formula TiAl2X8 · Ar (X = Cl, Br or I, Ar = benzene or hexamethylbenzene) and the complexes containing various amounts of Br or I in addition to Cl were prepared both by a direct synthesis — the reduction of titanium tetrahalide by aluminium in the aromatic solvent and in excess of the corresponding aluminium halide — and by halogen exchange between the complexes and aluminium halides. The interpretation of the electronic spectra of the complexes is given on the assumption of pseudooctahedral symmetry of the ligand field. The values of 10 Dq and B obtained are compatible with the assignment.

Equilibria in complexes of N-heterocyclic molecules, part XXI. Kinetics of reaction of hydroxide with bis [2,4,6-tri (2-pyridyl)-1,3,5-triazine] iron (II) and ruthenium(II)

Abstract: The kinetics of reaction of HO− with [Ru(TPT)2]2+ and [Fe(TPT)2]2+ have been studied in detail. The former participates in an equilibrium with HO− yielding a pseudo-base by attack at the ligand and, at very high concentrations of HO−, dissociates to yield pure TPT quantitatively. [Fe(TPT)2]2+ dissociates rapidly in basic solution, even at 273 K, however, [Fe(TPT)(TPT · OH)]+ does in fact exist and the Fell and Rull reactions are quite similar, although that of Fell is much faster. The implications of these findings for the dissociation of [Fe(TPT)2]2+ over a wide range of pH are discussed.

X-ray photoelectron spectroscopy of alkaline earth metal uranate complexes

Abstract: X-ray photoelectron spectra for MgUO4−x, MgU3O8.9, CaUO4−x, Ca2UO5, Ca3UO6, Ca2U3O11, CaU2O7, CaU4O12, SrUO4, SrUO3.67, Sr2U3O11, SrU4O12.8, Sr2UO5, Sr3UO6, BaUO4, Ba3UO6, BaU2O7, Ba2U2O7 and Ba2U3O11 have been recorded. Recorded O(1s) peak positions range from 529.5 to 533.4 eV and certain trends can be related to data obtained from other studies. By contrast, the range of U(4f) peak positions is much smaller totalling 0.7 eV. All compounds show satellite structure to the high binding energy side of the U(4f) peaks. Satellites separated byca. 10 eV from the main peaks are assigned to a transition from the uranium-oxygen bonding band to the U(6d) conduction band.

Ethyltetramethylcyclopentadienyl complexes of cobalt, rhodium, iridium and ruthenium

Abstract: The syntheses of the ethyltetramethylcyclopentadienyl complexes Ru(η5-C5Me4Et)(CO)2Cl, CO(η 5-C5Me4Et)(CO)2, and [M(η 5-C5Me4Et)Cl2]2 (M = Rh or Ir) are described; the ruthenium complex reacts with triphenylarsine to give Ru(η 5-C5Me4Et)(AsPh3)(CO)Cl.1H and13C n.m.r. spectra, i.r. spectra and the physical properties of the compounds are discussed and contrasted with the known C5H5 and C5Me5 analogues.

Preparation and crystal structure of a nickel (II)-Uranyl(VI) binuclear chelate

Abstract: The structure of the heterobinuclear complex of Ni2+ and [U022]2+ with the tetraanionic ligand derived from the condensation of 1,2-diaminoethane with o-acetoacetylphenol has been determined from diffractometer data and refined to R = 7.2%. The crystals are monoclinic, P21 /a, with α = 20.65(2), b = 8.58(1), c = 14.68(2) A and β = 97.78(5); Z = 4. The ligand employed has two different coordination sets of atoms, N2O2 and O2O2, two oxygen atoms being common to both donor sets. In the complex the nickel ion, which is four coordinate but not square planar, is retained in the inner N2O2 chamber, whilst the uranyl ion is incorporated in the outer O2O2 chamber. A molecule of solvent is retained to preserve the preferred seven coordination of uranium.

Preparation and characterization of bis(cyclopentadienyl)zirconium (IV) oximate complexes

Abstract: Oximate complexes of bis(cyclopentadienyl)zirconium(IV) chloride (Cp2ZrCl2 ) having the general formulae Cp2Zr(Ox), Cp2Zr(OxH)Cl and Cp2Zr(OxH)2 [where OxH2 = RC6H4C(OH)R′: NOH, R = H, Me, R′= H, Me, Et, n-Pr; PhC: N(OH)CH(OH)Ph and R″C : N(OH)N(OH): CR″, R″ = H, Me and Ph] have been synthesized by reacting bis(cyclopentadienyl)zirconium(IV) chloride with the appropriate oxime in tetrahydrofuran in the presence of triethylamine at room temperature. The complexes have been characterized by their elemental analysis, i.r. and electronic spectra, molecular weight determination, electrical conductance and magnetic measurements.

Iron(III) acetates

Abstract: The compound, Fe2CI2(OH)2(MeCO2)2 · 2MeCO2H · H2O, combines with lithium and silver acetates to form Fe2Cl(OH)2(MeCO2)3 · 2MeCO2H and Fe2(OH)2(MeCO2)4 · H2O, respectively. Iron(III)chloride in tetrahydrofuran reacts with silver acetate to give a precipitate consisting of a mixture of Fe(MeCO2)3 and AgCl which, when extracted with boiling acetic acid, yields

Structural researches on the chelating behaviour of the biguanide ligand. The crystal structures of Co(C2H6N5)3 · 2H2O and Cu(C2H7N5)2CO3·4H20

Abstract: Crystals of the title compounds are both monoclinic, with unit cell dimensions:a = 9.293(5),b = 10.122(5),c = 16.737(7) A.β = 103.44(3)°,Z = 4, space groupP21/c for the cobalt derivative;a = 13.1s5(7),b = 17.546(s),c = 6.871(3) A,β = 107.01(4)°Z = 4, space groupP21/n for the copper derivative. The structures were solved from diffractometer data by the heavy-atom technique for the first compound and by direct methods for the second compound. Refinement by block diagonal least-squares gaveR = 5.9% for 3511 independent reflections andR = 8.8% for 2885 independent reflections for the cobalt and copper compound respectively. In both compounds the biguanide moiety behaves as a bidentate chelating ligand in a symmetrical tautomeric form, but it is deprotonated in the octahedral cobalt compound and neutral in the square planar copper compound.

Preparation and characterization of some pyridine-2,6-dicarboxylato thorium(IV) complexes

Abstract: The preparation of complexes of pyridine-2,6-dicarboxylic acid (H2PDC) with thorium(IV) is reported and discussed. The reactivity of Th(PDC)2 (H2O)4(1) was tested by preparing adducts with some neutral ligands. The complexes were characterized by i.r. spectroscopy, elemental analysis and thermal behaviour. Preliminary information on the structure of(1) obtained by x-ray analysis, are also reported.

Synthesis, spectroscopic and magnetic properties of copper complexes with a ligand containing the pyridoxal moiety

Abstract: Seven new copper(II)pyridoxal salicyloylhydrazone complexes have been prepared and characterized by vibrational and electronic spectra and magnetic measurements. The u.v. absorption band maxima are compared with those of metal chelates of Schiff bases obtained from condensation of pyridoxal with amines or amino acids.

Syntheses and spectroscopic studies on group IIB metal 1,4-benzodiazepine complexes

Abstract: The preparation and characterization of some zinc(II) and cadmium(II) halide complexes with 1,3-dihydro-7-nitro-5-phenyl-2H-1,4-benzodiazepin-2-one and 7-chloro-l-methyl-5-phenyl-3H-1,4-benzodiazepin-2-one are reported. The complexes have been studied by means of magnetic susceptibility measurements, i.r. and far-i.r. spectra and conductivity measurements. Assignments for metalligand and metal-halide modes have been made. The evidence suggests that the complexes, which contain 1 : 1.5, 1 : 1, 1 : 2 and 1 : 4 metal : ligand stoichiometric ratios, have a pseudotetrahedral symmetry, with the exception of Zn(Mog)4Br2 ·2H2O which is octahedral.

Palladium(II), platinum(II), rhodium(III) and iridium(III) complexes coordinated with 2-aryl-4,5-dimethyl-1,2,3-triazoles as bidentate nitrogen-carbon chelate ligands

Abstract: Cyclometallations of 2-aryl-4,5-dimethyl-1,2,3-triazoles [H(C-N)] occur with palladium(II), platinum(II), rhodium(III) and iridium(III) chloride. Pallaciation and platination form [MCI(C-N)]2, and rhodation and iridation [MCI(C-N)2]2 species. These complexes react with monodentate ligands, L, such as pyridine and tri-n-butylphosphine to give MCl(C-N)L and MCl(C-N)2 L complexes. Corresponding bromo and iodo complexes are prepared by metathesis with lithium bromide and iodide. Spectroscopic data suggest that MX(C-N)L compounds (X = Cl, Br or I) have a structure withtrans-C,X andtrans-N,L, while [MX(C-N)2 L] has atrans-N,N,cis-C,C, andcis-X,L structure.