Synthesis of complexes containing silacyclobutane groupings and variable valence metals

Conclusions On the example of the synthesis of the complexes of 1-methyl-1-(3-pyridyl)-1-silacyclobutane with the cobalt and nickel halides it was shown that it is possible to obtain the complexes of the transition metals with heterocyeles that contain four-member ed silicon-carbon groups.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 135–137, January, 1973.     

变价态离子电极的理论模型

本文建立了表述变价态离子电极特殊行为的理论模型, 阐明了S-δ经验式及用δ-PH作图法求双质子化离子pKal的潜在机理, 提出更为简便而准确的pKal二阶微商计算法, 并依据电极电位随溶液PH变化的关系求出pKa2。     

Thiosemicarbazone complexes of the platinum metals. A story of variable coordination modes

Salicylaldehyde thiosemicarbazone (H₂saltsc) reacts with [M(PPh₃)₃X₂] (M = Ru, Os; X = Cl, Br) to afford complexes of type [M(PPh₃)₂(Hsaltsc)₂], in which the salicylaldehyde thiosemicarbazone ligand is coordinated to the metal as a bidentate N,S-donor forming a four-membered chelate ring. Reaction of benzaldehyde thiosemicarbazones (Hbztsc-R) with [M(PPh₃)₃X₂] also affords complexes of similar type, viz. [M(PPh₃)₂(bztsc-R)₂], in which the benzaldehyde thiosemicarbazones have also been found to coordinate the metal as a bidentate N,S-donor forming a four-membered chelate ring as before. Reaction of the Hbztsc-R ligands has also been carried out with [M(bpy)₂X₂] (M = Ru, Os; X = Cl, Br), which has afforded complexes of type [M(bpy)₂(bztsc-R)]⁺, which have been isolated as perchlorate salts. Coordination mode of bztsc-R has been found to be the same as before. Structure of the Hbztsc-OMe ligand has been determined and some molecular modelling studies have been carried out determine the reason for the observed mode of coordination. Reaction of acetone thiosemicarbazone (Hactsc) has then been carried out with [M(bpy)₂X₂] to afford the [M(bpy)₂(actsc)]ClO₄ complexes, in which the actsc ligand coordinates the metal as a bidentate N,S-donorformingafive-membered chelate ring. Reaction of H₂saltsc has been carried out with [Ru(bpy)₂Cl₂] to prepare the [Ru(bpy)₂(Hsaltsc)]ClO₄ complex, which has then been reacted with one equivalent of nickel perchlorate to afford an octanuclear complex of type [Ru(bpy)₂(saltsc-H)₄Ni₄](ClO₄)₄.     

Ligand redox activity and mixed valency in first-row transition-metal complexes containing tetrachlorocatecholate and radical tetrachlorosemiquinonate ligands

Ligand noninnocence occurs for complexes composed of redox-active ligands and metals, with frontier orbitals of similar energy. Usually methods of analysis can be used to define the charge distribution, and cases where the metal oxidation state and ligand charge are unclear are unusual. Ligands derived from o-benzoquinones can bond with metals as radical semiquinonates (SQ(?-)) or as catecholates (Cat(2-)). Spectroscopic, magnetic, and structural properties can be used to assess the metal and ligand charges. With the redox activity at both the metal and ligands, reversible multicomponent redox series can be observed using electrochemical methods. Steps in the series may occur at either the ligand or metal, and ligand substituent effects can be used to tune the range of ligand-based redox steps. Complexes that appear as intermediates in a ligand-based redox series may contain both SQ and Cat ligands "bridged" by the metal as mixed-valence complexes. Properties reflect the strength of metal-mediated interligand electronic coupling in the same way that ligand-bridged bimetallics conform to the Robin and Day classification scheme. In this review, we will focus specifically on complexes of first-row transition-metal ions coordinated with three ligands derived from tetrachloro-1,2-benzoquinone (Cl(4)BQ). The redox activity of this ligand overlaps with the potentials of common metal oxidation states, providing examples of metal- and ligand-based redox activity, in some cases, within a single redox series. The strength of the interligand electronic coupling is important in defining the separation between ligand-based couples of a redox series. The complex of ferric iron will be described as an example where coupling is weak, and the steps associated with the Fe(III)(Cl(4)SQ)(3)/[Fe(III)(Cl(4)Cat)(3)](3-) redox series are observed over a narrow range in electrochemical potential.     

Inhibition of the oxidation reaction of cumene by complexes of metals of variable valence with dimethyl- and diphenylglyoxime

Conclusions The complexes of Co, Ni, Fe, and Cu with dimethyl- and diphenylglyoxime inhibit the initiated oxidation of cumene by reacting with the peroxide radicals.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1342–1344, June, 1971.     

Thermal investigations of cefadroxil complexes with transition metals

The cefadroxil (Cef) complexes with transition divalent metals of the formula MCef·nH₂O (where n=2 for M=Cu²⁺, Ni²⁺, Zn²⁺ and n=3 for Co²⁺) and CdCef_1.5·4H₂O were prepared and characterized by elemental and infrared spectra. The thermal analysis of the investigated complexes in air atmosphere was carried out by means of simultaneous TG-DSC technique. During heating in air they lose bound water molecules and then decompose to oxides: Co₃O₄, NiO, CuO, ZnO and CdO. The CdCef_1.5·4H₂O complex forms probably an intermediate product Cd₂OSO₄. The combined TG-FTIR technique was employed to study of decomposition pathway of the investigated complexes. The first mass loss step is the water loss of the complexes. Next, decomposition of cefadroxil ligand occurs with evolution of CO₂ and NH₃. At slightly higher temperature COS is observed according to decomposition of cephem ring. Additionally, as decomposition gaseous products: HCN, HNCO (HOCN), H₂CNH, CO, SO₂, hydrocarbons and carbonyl compounds were observed. The formation of metal sulfates is postulated as solid intermediate product of decomposition in the argon atmosphere. This revised version was published online in July 2006 with corrections to the Cover Date.     

Vibrational spectra of complexes of norbornadiene with transition metals

Russian Chemical Bulletin -     

Norbornadiene complexes of transition metals

Conclusions Correlations were established between the stereochemistry of 2-(-carbinol)norbornadiene complexes of rhodium and their mass spectra.This study is also communication 30 from the series Mass Spectrometry of Transition Metal- Complexes.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2701–2703, December, 1982.     

Flammability of macrocyclic polymers and their complexes with metals

The peculiarities of thermal degradation and the flammability of nitrogen-containing macrocyclic polymers have been investigated. It has been shown that the thermal and thermo-oxidative stability of these polymers depend on the structure of the macrocycle, the type of organic radicals of the main unit and the metal nature. The effect of the type of n-conjugated macromolecules, as well as of the planarity and symmetry of macrocycle, on thermal stability as well as flammability of macrocyclic polymers has been studied. Metals (Cu, Co, Ni) in the coordination sphere increase the thermal stability and decrease the thermo-oxidative degradation of macrocyclic polymers.     

Dipicolinate complexes of main group metals with hydrazinium cation

Some new coordination complexes of hydrazinium main group metal dipicolinate hydrates of formulae (N₂H₅)₂M(dip)₂.nH₂O (where, M = Ca,Sr,BaorPb andn = 0, 2, 4 and 3 respectively and dip = dipicolinate), N₂H₅Bi(dip)₂.3H₂O and (N₂H₅)₃Bi(dip)₃.4H₂O have been prepared and characterized by physico-chemical techniques. The infrared spectra of the complexes reveal the presence of tridentate dipicolinate dianions and non-coordinating hydrazinium cations. Conductance measurements show that the mono, di and trihydrazinium complexes behave as 1:1, 2:1 and 3 :1 electrolytes respectively, in aqueous solution. Thermal decomposition studies show that these compounds lose water followed by endothermic decomposition of hydrazine to give respective metal hydrogendipicolinate intermediates, which further decompose exothermically to the final product of either metal carbonates (Ca, Sr, Ba and Pb) or metal oxycarbonates (Bi). The coordination numbers around the metal ions differ from compound to compound. The various coordination numbers exhibited by these metals are six (Ca), seven (Ba), eight (Sr) and nine (Pb and Bi). In all the complexes the above coordination number is attained by tridentate dipicolinate dianions and water molecules. The X-ray diffraction patterns of these compounds differ from one another suggesting that they are not isomorphous.     

Structural diversity of 1,2,4-diazaphospholide complexes with alkali metals

Treatment of H[3,5-Ph2dp] (Hdp = 1H-1,2,4-diazaphosphole) with nBuLi or KH, or the reaction of K[3,5-tBu2dp] with an excess amount of O2, afforded the dimeric species [(eta2,eta1-3,5-Ph2dp)Li(THF)2]2 and the polymeric complexes [(eta2:eta4-3,5-Ph2dp)K(Et2O2]n, and [[(eta2:eta5-3,5-tBu2dp)K(THF)][eta2(N,N)-eta3(O,P,O)-3,5-tBu2dp-(O,O)O2K]]n, respectively.     

Direct C-H carboxylation with complexes of the coinage metals

Advances into the functionalisation of C-H bonds by coinage metal complexes that make use of carbon dioxide are described.     

Macrocyclic complexes of transition metals with divalent polyaza units

A new series of 14–16-membered hexaazamacrocyclic complexes [ML¹X₂] and [ML²X₂] (M = Co^II, Ni^II, Cu^II and Zn^II; X = Cl or NO₃) have been synthesized by template condensation of phenylenediamine, primary diamines and formaldehyde solution 35% in MeOH and have been characterized by i.r., 1H-n.m.r., e.p.r., and u.v. spectroscopy as well as by magnetic susceptibility and conductivity measurements. An octahedral geometry has been suggested for all the complexes.     

Trimellitate complexes of divalent transition metals with hydrazinium cation

New dihydrazinium divalent transition metal trimellitate hydrates of empirical formula (N₂H₅)₂M(Html)₂·nH₂O, where n = 1 for M = Co or Ni, and n = 2 for M = Mn, Zn, or Cd (H₃tml = trimellitic acid), and monohydrazinium cadmium trimellitate, [(N₂H₅)Cd(Html)_1.5·2H₂O] have been prepared and characterized by physico-chemical methods. Electronic spectroscopic, and magnetic moment data suggest that Co and Ni complexes adopt an octahedral geometry. The IR spectra confirm the presence of monodentate carboxylate anion (Δν = ν_asy(COO^?) ? ν_sym(COO^?) > 190 cm^?1) and coordinated N₂H₅ ⁺ ion (ν_N–N 1015 ? 990 cm^?1) in all the complexes. All the complexes undergo endothermic decomposition eliminating CO₂ in the temperature region 200–250 °C, followed by exothermic decomposition (in the range of 500–570 °C) of organic moiety to give the respective metal carbonate as the end products except nickel and cobalt complexes, which leave respective metal oxides. X-ray powder diffraction patterns reveal that Ni and Co complexes are isomorphous as are those of, Zn(II) and Cd(II) of the type, (N₂H₅)₂M(Html)₂·2H₂O.     

Reaction of peroxydisuccinic acid with salts of metals of variable valence

Conclusions A study was made of the effect of the salts FeSO₄, MnSO₄, and CoSO₄ on the decomposition of peroxydisuccinic acid in aqueous medium. Both the composition and the yield of the reaction products are determined to a large degree by the nature of the metal ion.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2060–2062, September, 1971.