Showing papers in "Inorganic Chemistry in 1979"

Properties and reactivities of pentadentate ethylenediaminetetraacetate complexes of ruthenium(III) and -(II)

Abstract: The reaction of the pentadentate edta complex of ruthenium(III) with various entering ligands L has been studied as a function of pH, temperature, and L at 0.2 M ionic strength in aqueous solution. Over the pH range 0.8 to 8.5, the species Ru/sup III/(edta)H/sub 2/O/sup -/ is the sole form reactive in the substitution processes. Both forward (k/sub 1/) and reverse (k/sub -1/) rate constants Ru(edta)H/sub 2/O/sup -/ + L in equilibrium (k/sub 1/,k/sub -1/) Ru(edta)L/sup -/ + H/sub 2/O have been determined, as well as activation parameters for the complexation (k/sub 1/) process (L, k/sub 1/ in M/sup -1/s/sup -1/ (25/sup 0/C), k/sub -1/ in s/sup -1/ (25/sup 0/C), ..delta..H/sub 1//sup +/ in kcal mol/sup -1/, ..delta..S/sub 1//sup +/ in cal deg/sup -1/ mol/sup -1/): acetonitrile, 30 +- 7, 3.2 +- 0.2, 8.3 +- 0.5, -24 +- 4; thiocyanate, 270 +- 20, 0.5 +- 0.1, 8.9 +- 0.5, -18 +- 3; pyridine, 6300 +- 500, 0.061 +- 0.002; isonicotinamide, 8300 +- 600, 0.7 +- 0.2, 6.6 +- 0.5, -19 +- 3; pyrazine, 20,000 +- 1000, 2.0 +- 0.5, 5.7 +- 0.5, -20 +- 3. Forward rate constants for the analogous substitution reaction for Ru/sup II/(edta) H/sub 2/O/sup 2 -/more » (25/sup 0/C, 0.2 M ionic strength) are as follows: thiocyanate, 2.7 +- 0.2 M/sup -1/s/sup -1/; acetonitrile, 13 +- 1 M/sup -1/s/sup -1/; isonicotinamide, 30 +- 15 M/sup -1/s/sup -1/. The substitution reactions of Ru/sup III/(edta)H/sub 2/O/sup -/ proceed by an associative mechanism, while those of Ru/sup II/(edta)H/sub 2/O/sup 2/- appear to be dissociative in nature. Spectra and reduction potentials for the Ru(edta)L/sup -/2-/ complexes are reported. 4 figures, 11 tables.« less

Diagnostic features of transition-metal-SO/sub 2/ coordination geometries

Abstract: SO/sub 2/ complexes have been carefully examined in regard to possible correlations involving their physicochemical properties and SO/sub 2/ coordination geometries (coplanar MSO/sub 2/, pyramidal MSO/sub 2/, bridging MSO/sub 2/M, O,S-bonded SO/sub 2/, or ligand-SO/sub 2/ interaction). On a 1 : 1 basis, general correlations of geometry with SO infrared stretching frequencies, reversibility of SO/sub 2/ binding, and tendency of a complex to undergo the sulfato reaction can be made, but exceptions do exist. However, certain combinations of properties have been found to be diagnostic of specific geometries and appear to be useful criteria for identifying modes of SO/sub 2/ binding. The synthesis and properties of two new complexes, Ir(SPh)(CO)(PPh/sub 3/)/sub 2/(SO/sub 2/) and (RhCl(PPh/sub 3/)/sub 2/(SO/sub 2/))/sub 2/, are described in relation to the above correlations. These species as well as RhCl(PPh/sub 2/Me)/sub 3/(SO/sub 2/) were found to react with atmospheric oxygen to form sulfates, which also were isolated and characterized. 2 figures, 2 tables.

Catalysts of supported iron derived from molecular complexes containing one, two, and three iron atoms

Abstract: The syntheses and characterization of catalysts derived from Fe(CO)5, Fe,(C0)9, and Fe3(C0)12 supported on 7-AI2O3 are described. The temperature-programmed decomposition (TPDE) spectra of the Fe(CO), and Fe3(CO)12 catalysts are different, suggesting that the nuclearity of the precursor complex can influence the chemistry of supported complexes. Fe2(C0)9 dry mixed with A1203 probably undergoes some decomposition to Fe(CO)5 and Fe3(C0)12 prior to bonding to the support. Activation at low temperatures (51 50 "C) leads primarily to the formation of zerovalent subcarbonyl species, some of which are reversibly formed. Activation at high temperatures (2300 "C) leads to extensive oxidation of the Fe by reaction with the surface hydroxyl groups of the A1203 and loss of reversibility. Compared to the TPDE of the bulk unsupported carbonyls, A1203 stabilizes subcarbonyl species over a broad range of temperatures and inhibits their migration, preventing the formation of an Fe mirror. Chemisorption of CO indicates that catalyts derived from the iron carbonyls can be more than an order of magnitude more dispersed than catalysts synthesized by the traditional technique of impregnation with salts of Fe3+

Interaction of hydrazine with copper(II) chloride in acidic solutions. Formation, spectral and magnetic properties, and structures of copper(II), copper(I), and mixed-valence species

Abstract: : The reaction of hydrazine with copper(II) chloride in acidic aqueous solution has been shown to produce at least four distinct complexes. Hydrazine behaves as a reducing agent, leading to the white, diamagnetic copper(I) complex (N2H4)CuCl and the black paramagnetic mixed-valence copper(I,I,II) complex (N2H5)2Cu2Cl6. Blue and green copper(II) complexes (N2H5)2CuCl4 2H2O and (N2H5) CuCl3 are also formed. Infrared spectra establish the presence of coordinated hydrazinium ions in the blue, green, and black compounds. Structures are proposed for all of these materials based on spectroscopic and magnetic measurements.

Novel reactions of metal-metal bonds. Addition of sulfur dioxide and sulfur to dichlorobis(bis(diphenylphosphino)methane)dipalladium and the oxidation of coordinated sulfide

Abstract: Sulfur dioxide inserts into the metal-metal bond of Pd/sub 2/(dpm)/sub 2/X/sub 2/ (dpm = bis(diphenylphosphino)methane, X = Cl or Br), Pd/sub 2/(dam)/sub 2/Cl/sub 2/ (dam = bis(diphenylarsino)methane), and Pt/sub 2/(dpm)/sub 2/Cl/sub 2/. The adducts have been crystallized and characterized by infrared, electronic, and /sup 1/H NMR spectroscopy. The structure of Pd/sub 2/(dpm)/sub 2/(..mu..-SO/sub 2/)Cl/sub 2/ has been determined by x-ray crystallography. The compound crystallizes in the orthorhombic space group P2/sub 1/2/sub 1/2/sub 1/ with four molecules per unit cell of dimensions a = 15.582 (3), b = 16.457 (3), and c = 19.184 (5) A. Full-matrix least-squares refinement yields R = 0.069. The binuclear molecules contain two approximately planar palladium ions, each coordinated to a terminal chloride, a bridging sulfur dioxide, and two trans phosphorus donors from the bridging diphosphines. The ability of crystal packing forces to alter the Pd...Pd separation (3.383 (4) and 3.220 (4) A for the two crystallographically independent molecules) reflects the lack of a direct metal-metal bond. Pd/sub 2/(dpm)/sub 2/Cl/sub 2/ reacts with cyclo-octasulfur or propylene sulfide to give Pd/sub 2/(dpm)/sub 2/(..mu..-S)Cl/sub 2/, which has been crystallized and characterized by infrared, electronic, and /sup 1/H NMR spectra. Crystals of Pd/sub 2/(dpm)..mu..-S)Cl/sub 2/ are tetragonal, space groupmore » P4/sub 1/, with Z = 4 and cell dimensions a = 21.015 (4) and c = 14.281 (2) A. Refinement of this complex yields an R of 0.076. Oxidation of Pd/sub 2/(dpm)/sub 2/(..mu..-S)Cl/sub 2/ with m-chloroperbenzoic acid has been monitored by electronic spectroscopy at -60/sup 0/C; Pd/sub 2/(dpm)/sub 2/(..mu..-SO/sub 2/)Cl/sub 2/ is formed. The utility of the /sup 1/H NMR spectra of the methylene region of these dpm-bridged complexes in diagnosing the structure of the complexes is discussed. 5 figures, 8 tables.« less