Complexes Of Stoicheiometry Research Articles

New organyltellurium ligands. 1,2-bis( p-ethoxyphenyltelluromethyl)benzene and tetrakis( p-ethoxyphenyltelluromethyl)methane

The synthesis and characterisation, particularly by 13C NMR spectrocopy, of 1,2-bis( p-ethoxyphenyltelluromethyl)benzene and tetrakis( p-ethoxyphenyltelluromethyl)methane are reported. A preliminary investigation of the coordination chemistry of 1,2-bis( p-ethoxyphenyltelluromethyl)benzene (I) has given complexes of stoicheiometry [PdCl·(I)], [PtCl·(I)] and [HgCl·(I)], which are insoluble and generally intractable. Some physical data, particularly low frequency infrared spectra and 125Te Mössbauer spectra, are briefly discussed.

Dinuclear metal complexes. Part 4. Electrochemical studies of macrocyclic dicopper(II) complexes. Investigation of the effect of solvents, donor groups, and steric constraints on the stability of mixed-valence copper(II)–copper(I) complexes

Two series of macrocyclic dicopper(II) complexes of stoicheiometry [Cu2L][ClO4]2·2H2O have been synthesized and characterized. Compounds belonging to series (1) are derived from the 6,12,18,24-substituted (H,H,Me,Me; H,H,Me,Ph; Me,Me,Me,Ph; Me,Me,Ph,Ph) macrocycie 7,11;19,23-dimetheno-9,21-dimethyl-1,5,13,17-tetra-azacyclotetracosa-5,7,9,12,17,19,21,24-octaene-25,26-diol (H2L). Complexes belonging to series (2) are related to those of series (1) by replacement of two of the –CHN– linkages by –CH2–NH– groups and the segment containing two azomethine linkages having the 6,12-substituents H,H; Me,Me; Me,Ph; Ph,Ph. The electrochemistry of these compounds has been investigated in MeCN and CH2Cl2 solvents using platinum and glassy carbon electrodes. In all cases cyclic voltammograms show sequential one-electron transfers at two different potentials, and from these data the conproportionation constant (Kc) and free energy of the mixed-valent species (ΔGc) have been evaluated. Electrochemical results have been analysed in terms of the effect due to solvent, donor groups, and steric constraints. Values of Kc for all of the compounds are greater in MeCN than those in CH2Cl2, and the Kc value for any compound belonging to series (1) is greater than its analogue in series (2). Factors affecting stability and intramolecular electron-transfer rates of CuIICuIL+ species are discussed.

Seven-co-ordination in metal complexes of quinquedentate macrocyclic ligands. Part IV. Crystal and molecular structures of two pentagonal bipyramidal iron (II) complexes

The crystal structures of two iron(II) complexes of stoicheiometry [FeL(NCS)2], where L is a 15- or 16-membered ‘N5’ macrocycle, have been determined. Crystals of (I)(L = C15N5H23) are triclinic with a= 12.923(11), b= 7.165(9), c= 11.673(8)A, α= 93.24(11), β= 90.75(11), γ= 110.40(12)°, Z= 2, space group P. Crystals of (II)(L = C16N5H25) are monoclinic, space group P21/c with a= 7.746(8), b= 11.747(12), c= 24.367(18)A, β= 102.08(12)°Z= 4. The two structures were solved by Patterson and Fourier methods from 1 057 and 1 131 independent reflections above background collected by counter methods and refined to R 0.058 and 0.060, respectively. In both structures, the metal atoms have distorted pentagonal bipyramidal environments with the thiocyanate ligands in axial positions and the five nitrogen aioms of the macrocycle in equatorial positions. The Fe–N bond lengths and the conformations of the girdles are different in the two molecules as a consequence of the extra CH2, group in (II). However, both molecules have similar structures to those of the analogous FeIII cations.

Reactions of some conjugated diynes with cobalt carbonyl compounds

Treatment of dodecacarbonyltetracobalt with the conjugated diynes RC≡CC≡CR (R = CH3, C6H5) yields complexes of stoicheiometry [Co2(CO)6]2- (RC2C2R). The same complexes are obtained from octacarbonyldicobalt and the appropriate diyne. ��� A similar type of complex was obtained from para-(C6H5C2)2C6H4 and Co4(CO)12. Surprisingly, this complex was not isolated on reaction of the diyne with Co2(CO)8. ��� The infrared, nuclear magnetic resonance, and mass spectra of the complexes are given, and the probable structures of the compounds are deduced from these spectroscopic properties.

Nitrile complexes of tervalent molybdenum

Complexes of stoicheiometry [MoCl5L]2–(L = MeCN, EtCN, CH2:CH·CN, and PhCN), and [MoCl3L3]0(L = MeCN, EtCN, CH:2CH·CN, PhCN, and PhCH2·CN), have been isolated and their properties investigated. Assignments for the electronic spectra are discussed and evidence is presented that chlorine–metal charge transfer occurs at lower energies than for the nitrile–metal transitions.

Iodine adducts of Co-ordinated isothiocyanate groups

The previously known complexes of stoicheiometry M py4(NCS)2(I2)2, where M = Co or Ni, have been prepared anew, and these, and a related new compound, Ni(4-methylpyridine)4(NCS)2(I2)2, have been shown by spectroscopic studies to contain the grouping M–NCS–I–I.