Spectrochemical properties of molybdo- and tungsto-heteropolyanions containing Ce(IV) or Ce(III) as a heteroatom

The absorption and MCD spectra in the VIS-UV region of the traditional Silverton-type polyanion [Ce(IV)Mo₁₂O₄₂]^8? and Weakley-type polyanions, [X(W₅O₁₈)₂]^itn? [X = Ce(IV) and Ce(III)], have been measured and two charge-transfer transitions, ligand-to-heteroatom and intra-ligand, are discussed.     

Crystalline phase effects on esca valence bands of Zr(IV) and Ti(IV) acid phosphates

The valence bands (V.B.) of ESCA spectra of Zr(IV) and Ti(IV) acid phosphates in different crystalline phases are reported. The various bands are assigned by comparison with Li₃PO₄. Variations on changing the crystalline phase for compounds having the same M(IV) ion are found. Two types of molecular orbitals are mainly involved. One related to PO bonds is affected by the crystalline phase. The other, related to M(IV)O bonds and confined into the layers of the compounds, are less sensitive to crystalline environment. Variation in the symmetry of the tetrahedral type PO^3?₄ anion are proposed to be mainly responsible of the observed effects.     

Halide and complex halogeno anions as salts of oxinato bis(η5-indenyl)titanium(IV)/zirconium(IV) chelates

Bis(η⁵-indenyl)titanium(IV) dichloride and bis(η⁵-indenyl)zirconium(IV) dichloride, when treated with 8-hydroxyquinoline (oxine) in aqueous medium form ionic derivatives of the type [(η⁵-C₉H₇)₂ML]⁺Cl^? (M = Ti(IV), Zr(IV), L is the conjugate base of oxine). A number of halide and complex halogeno anions present in aqueous solution were isolated as salts of these ionic complexes giving derivatives of the type, [(η⁵-C₉H₇)₂ML]⁺X^? (X = Br^?, I^?, ZnCl₃(H₂O)^?, CdCl₄^2?, HgCl₃^?). Conductivity measurements in nitrobenzene indicate that these complexes are electrolytes. Both the IR and ¹H NMR spectral studies demonstrate that the ligand L is chelating. Consequently there is tetrahedral coordination about the titanium(IV) or zirconium(IV) ion.     

Kinetics and mechanism of the interaction of hexaaquochromium(III) with octacyanomolybdate(IV) ions

The kinetics of the interaction of hexaaquochromium(III) ion with potassium octacyanomolybdate(IV) have been studied using conductance and spectrophotometric data. The mechanism of the reaction is discussed and the effect of H⁺ ion and the ionic strength on the rate of the reaction determined. The reaction is found to be pseudo-first order with respect to potassium octacyanomolybdate(IV) and inverse first order with [H₃O⁺]. The rate of the reaction increases with increase in ionic strength and temperature. Activation parameters have been calculated using the Arrhenius equation and have the values ΔE^* = 1.3 × 10² kJ mol^?1, ΔH^* = 129 kJ mol^?1, ΔS^* = ?315 e.u., ΔF^* = 2.3 × 10² kJ and A = 1.5 × 10^?3. The mechanism proposed is based on ion-pair formation and the rate equation obtained is given by: k_obs=$\text{[}{}_{\mathrm{kK}}{}_{\mathrm{<mtext>E</mtext>}}\text{[H}{}_3\text{O}{}^{\mathrm{+}}\text{]+}\text{k′K′k}{}_{\mathrm{E}}\text{k}{}_{\mathrm{h}}\text{][Mo(CN)}{}_8{}^{\mathrm{4?}}\text{]}\text{[H}{}_3\text{O}{}^{\mathrm{+}}\text{]+}\text{k}{}_{\mathrm{<mtext>h</mtext>}}\text{+[}\text{K}{}_{\mathrm{<mtext>E</mtext>}}\text{[H}{}_3\text{O}{}^{\mathrm{+}}\text{]+}\text{K′}{}_{\mathrm{E}}\text{k}{}_{\mathrm{h}}\text{][Mo(CN)}{}_8{}^{\mathrm{4?}}\text{]}$     

Bis(indenyl)titanium(IV) and zirconium(IV) complexes of monofunctional bidentate salicylidimines

Dichlorobis(indenyl)-titanium(IV) and -zirconium(IV), (C₉H₇)₂TiCl₂ and (C₉H₇)₂ZrCl₂, react with bidentate Schiff bases such as salicylidene aniline, salicylidene-o-toluidine, salicylidene-m-toluidine and salicylidene-p-toluidine in a 1:1 molar ratio in refluxing tetrahydrofuran in the presence of triethylamine to yield complexes of the type (C₉H₇)₂Ti(SB)Cl and (C₉H₇)₂Zr(SB)Cl, respectively where SB is the anion of the corresponding Schiff base, SBH. The new derivatives have been characterised on the basis of their elemental analyses, conductance measurements and spectral (IR, ¹H NMR and electronic) studies.     

Formation and thermodynamic properties of mixed complexes of Cd(II) with thiourea and nitrite or thiosulphate ions as ligands

Formation and thermodynamic parameters of mononuclear mixed complexes Cd(SCN₂H₄)_n(NO₂)^2?p_p and Cd(SCN₂H₄)_n(S₂O₃)^2(1?p_p in aqueous solution were investigated by potentiometric measurements at different temperatures and μ = 1 for KNO₃.     

Nitrosolates and related compounds—IX: Coordination compounds of divalent copper,nickel and cobalt with nitroacetate(2−) ions as chelating ligands. Crystal and molecular structure of potassium bis[nitroacetato(2−)]cuprate(II)-water (1/1)

The syntheses of K₂[Cu(nac)₂]·H₂O (4), [Cu(nac)(N-N)(H₂O)]·H₂O (N-N = bpy, phen; 5,6) and [M(nac)(N-N)₂]·xH₂O (M = Ni, Co; 7–10) with nitroacetate(2?) ions (nac^2?) as chelating ligands are described.The structure of 4 has been determined by single crystal X-ray diffraction and contains square planar [Cu(nac)₂]^2? units in which the nitro and carboxyl groups of the two chelate ligands are in cis positions. Two of the units form a centrosymmetric dimer with a four-membered CuOCu“O”-ring, the dimers being connected by exo-oxygens of the ligands into two-dimensional layers. The water molecules and the potassium ions are arranged between the layers; there are two kinds of potassium ions with distorted (1+4+1) and (2+4+3) coordinations respectively.     

Reactions of collman complex with tin(IV) and germanium(IV) porphyris,formation of [tin(II) and germanium(II) porphyrins] tetracarbonyliron and crystal structure of [2,3,7,8,12,13,17,18-octaethylporphinato tin(II)] tetracarbonyliron

The action of Na₂Fe(CO)₄ with tin(IV) and germanium(IV) porphyrins affords metal(II) porphyrin complexes [(por)M(II)Fe(CO)₄] (por = porphyrinate, M - Sn(II) or Ge(II)). The molecular structure of [(oep)Sn(II)Fe(CO)₄] was solved by X-ray diffraction techniques. The molecular structure of [(oep)Sn(II)Fe(CO)₄] was solved by X-ray diffraction techniques : the Sn coordination is square pyramidal with the iron in axial position (Sn-Fe = 2.492(1)Å) whereas the Fe coordination is trigonal bipyramidal. Mössbauer parameters provide convincing evidence for the formal zero oxidation state of the iron atom.     

Pentamethylcyclopentadienylplatinum(IV) complexes

Reaction of dichloro(η⁴-pentamethylcyclopentadiene)platinum with bromine yields a η⁵-pentamethylcyclopentadienylplatinum(IV) complex which is formulated as [C₅Me₅PtBr₃PtC₅Me₅]Br₃.     

New mixed heteropolytungstates containing Ge(IV) or Sn(IV)

New mixed heteropolyanions with formulae XZW₁₁O₃₉(OH)^m?[X = Si, Ge, B, As(V), Ga, Co(II), Zn; Z = Ge(IV), Sn(IV)] and X₂′ZW₁₇O₆₁(OH)^7?[X′= As(V), P(V);Z = Ge(IV), Sn(IV)] were prepared. Crystal systems of the potassium salts were determined. The stability range of the anions is given in terms of the pH. The acids corresponding to the salts were obtained and their neutralization studied. Spectroscopic and polarographic reduction studies are reported.     

Isolation of dithiocarbamate anions as salts of biscyclopentadienyl titanium(IV) chelates

A series of [Cp₂TiL]⁺[RR′NCS₂]^? complexes, where L is the conjugate base of acetylacetone, benzoylacetone or 8-hydroxyquinoline and R = CH₃, R′ = C₆H₅CH₂; R = C₂H₅, R′ = C₆H₄CH₃; R = H, R′ = C₅H₉; RR′ = C₆H₁₂, have been synthesised in aqueous medium by the reaction of [Cp₂TiL]⁺Cl^? with RR′NCS^?₂Na⁺. Conductivity measurements in nitrobenzene solution indicate that these complexes are electrolytes. Both the IR and NMR studies demonstrate that the ligand L is chelating in all these complexes. Consequently, tetrahedral coordination about the titanium atom is proposed. In addition to these studies, elemental analyses and magnetic susceptibility have been carried out for these complexes.     

Hafnium(IV)-nitrilotriacetate and hafnium(IV)-fluoride complexes investigated using an ion-selective electrode

Models of plutonium solution chemistry in vivo require formation constants which are difficult to obtain but hafnium(IV) is biochemically similar t     

Tetrahedral and octahedral coordination for cobalt(II) complexes of N-isopropyl-2-pyrrolidinone

Complexes of the formulas [Co(NIPP)₄](ClO₄)₂ and [Co(NIPP)₆](ClO₄)₂ have been synthesized and isolated (NIPP = N-isopropyl-2-pyrrolidinone). IR spectra and conductance data are presented as proof that perchlorate coordination in [Co(NIPP)₄](ClO₄)₂ does not occur. Vibrational spectra indicate that coordination occurs through the NIPP carbonyl oxygen for both complexes. Spectral parameters obtained from the electronic spectra and magnetic moments indicate tetrahedral and octahedral coordination for [Co(NIPP)₄](ClO₄)₂ and [Co(NIPP)₆](ClO₄)₂, respectively. The powder X-ray diffraction data appear to support the assignments of these two geometries. The crystal-field prediction that Δ(T_d)/Δ(O_h) = 0.44 is in reasonably good agreement with the experimental results.     

Reactions of nickel ions with nitroso-naphthols—IV formation kinetics of nickel (1-nitroso-2-naphthol-6-sulphonate)

The formation kinetics of Ni(1-nitroso-2-naphthol-6-sulphonate) are reported in the temperature range 20-30°C at an ionic strength of 0.1 M. Both the acidic (HL^?) and basic (L^2? forms of the ligand react with nickel ions, the latter at a much higher rate. The rate constants are similar in magnitude to those observed with 1-nitroso-2-naphthol-3, 6-disulphonate and variation of rate constant with respect to temperature is reproduced by the equation.     

Complexes of Pt(II) and Pt(IV) with disubstituted purines

Mixed-ligand complexes of Pt(II) and Pt(IV) with 2,6-diaminopurine and 6-thioguanine were synthesized and characterised. The complexes were prepared in acidic and basic media. The binding of the ligands to the metal ion varies according to the pH of the medium. Thus, in the complexes of 6-thioguanine, the ligand acts as a monodentate ligand coordinating through the neutral C₆-SH group in the acidic medium and in the basic medium as a bidentate ligand binding to the metal ion through C₆S^? and N₇, forming a five-membered chelate ring. In an acidic medium 2,6-diaminopurine forms mononuclear complexes with Pt(II) and Pt(IV) binding through N₇. In a basic medium binuclear hydroxobridged complexes are formed with Pt(IV) and the ligand is monodentate, coordinating through N₇.     

Chemistry of iron complexes—IV. Spectroscopic,magnetic and other properties of complexes of iron(II) iodide and iron(II) tetracarbonyl iodide with b

Bis(tertiaryphosphine/arsine oxides), Ph₂E(O) (CH₂)_nE(O)Ph₂ react with iron(II) iodide and iron(II) tetracarbonyliodide forming com     

Magnetochemical properties of tetranuclear rhodoso and Pfeiffer chromium(III) complexes in a series of compounds

Seven salts of the structurally related tetranuclear rhodoso and Pfeiffer chromium(III) complexes were prepared. Magnetic susceptibilities were measured and the energy splittings of the electronic ground state caused by exchange interactions were determined. There are marked differences in the low-temperature magnetic properties. Crystal packing and hydrogen bonding effects are the most likely causes for the differences in the exchange-splitting pattern.     

π-Allylmetal chemistry.IV. Structures and equilibria in Crotylplatinum(II) complexes

Simple methods to prepare crotylplatinum(II) complexes of the type, Pt(CH₂CHCHMe)Cl(PPh₃)₂ and Pt(CH₂CHCHMe)C1L (L PPh₃, AsPh₃), are described. ¹H NMR and vibrational spectral evidence suggests that the σ-allylic form is the dominant species in a benzene solution of Pt(CH₂CHCHMe)Cl(PPh₃)₂, while in chloroform this compound has the ionic α-allyl structure with both the anti and syn-methyl isomers present. Various rate processes exhibited by Pt(CH₂CHCHMe)C1L₂ (L PPh₃ , AsPh₃) in different solvents have been discussed in terms of the structures of intermediate σ-allylic complexes and the different coordinating abilities of L.     

Mono- and bisphenoxy derivatives of bis(indenyl)zirconium(IV)

A series of (C₉H₇)₂Zr(OAr)Cl and (C₉H₇)₂Zr(OAr)₂ complexes, where Ar = C₆H₅, p-ClC₆H₄, α-C₁₀H₇, or β-C₁₀H₇, have been synthesised by the reaction of bis(indenyl)zirconium(IV)-dichloride with an appropriate phenol in a 1:1 and 1:2 molar ratio in refluxing benzene in the presence of triethylamine. These complexes have been characterised by elemental analyses, conductance measurements and spectral (IR, ¹H NMR and electronic) studies.     

New syntheses of platinum (IV) and platinum (VI) fluorides

γ-Ray and peroxide-initiated additions of dimethylether to F-cyclobutene, F-cyclopentene, and F-cyclohexene give mixtures of $\text{cis-}$ and $\text{trans-}$ adducts in each case, with a clear preference for $\text{trans}$-addition with F-cyclobutene. Selective bromination of the adducts occurs but the position of chlorination depends dramatically on solvent. Fluorination with cobalt trifluoride is very efficient.