Mario Nardelli

Structure and catalytic activity of phosphine-substituted ruthenium carbonyl carboxylates

Abstract The structures of the [{Ru(CO) 2 (μ-OOCCH 3 )L} 2 ] with L = P n Bu 3 , P t Bu 3 or P i Pr 3 have been determined and their catalytic activity tested in the hydrogenation of internal and terminal olefins, of the carbonyl double bond and of both free and esterified carboxylic groups. There is a correlation between the PRuRuP torsion angle and the catalytic activity of the complex.

Structural researches on organotin(iv) compounds. synthesis and structure of nitratotriphenyl(triphenylphosphine oxide)tin(iv)

Abstract A nitrato-complex of organotin(IV) containing triphenylphosphine oxide, Sn(C 6 H 5 ) 3 (NO 3 ) [(C 6 H 5 ) 3 PO], has been synthesized and characterized by infrared spectroscopy and X-ray structural analysis. The compound crystallizes in space group P 1¯, with a = 11.817(6), b = 11.086(6), c = 12.471(6), α = 99.6(1),β = 90.8(1), γ = 97.8(1), Z = 2. The structure has been solved from X-ray diffractometer data by Patterson and Fourier methods and refined by least-squares calculations to R = 6.4% for 4301 independent reflections. The structure consists of discrete monomer units in which tin shows trigonal bipyramidal geometry.

A structural study of metal binding of gem-diphosphonates, bone growth regulators

The crystal structures of sodium dichloromethylenediphosphonate tetrahydrate and calcium dichloromethylenediphosphonate pentahydrate, determined from single crystal X-ray diffractometer data, are compared with those of other bone growth regulators ( gem -diphosphonates and pyrophosphates). Na 2 CCl 2 (PO 3 H) 2 ·4H 2 O crystallizes triclinic (P with Z = 2 formula units in a cell of constants: a = 11.27(2), b = 9.18(2), c = 5.91(1) A , α = 88.57(2)°, β = 92.69(2)°, γ = 90.58(2)°; final R = 0.0359 and R w = 0.0453. The two crystallographically independent sodium ions both show octahedral coordination, but, while one of them is coordinated by two couples of oxygens from two chelating diphosphonate anions plus a chlorine atom and a water molecule, the other is surrounded by three oxygen atoms from three different diphosphonate anions and three water molecules. Two couples of these octahedra, sharing edges, form tetrameric clusters joined together by diphosphonate bridges. CaCCl 2 (PO 3 H) 2 ·5H 2 O crystallizes orthorhombic ( Pnma ) with unit cell dimensions: a = 10.278(2), b = 10.872(2), c = 11.899(2) A, Z = 4; final R = 0.0389 and R w = 0.0449. Calcium is heptacoordinated by two oxygen atoms from a diphosphonate anion acting as a bidentate chelating agent, and five water molecules. The coordination polyhedron can be described as a distorted monocapped trigonal prism. Chlorine is not involved in coordination to the metal. In both compounds the diphosphonate anion interacts with the cation through deprotonated oxygen atoms and assumes a nearly eclipsed conformation which gives a O⋯O bite distance as short as 3.06–3.27 A which seems particularly suitable for a bidentate chelation to calcium and is characteristic of this class of calcium phosphate metabolism regulators.

Coordination behaviour of diphosphine and diarsine oxides in four organotin(IV) adducts

Abstract Four new molecular adducts of diphenyl- and triphenyl-tin(IV) nitrates with 1,2-bis(diphenylarsoryl)ethane (dpaoe), bis(diphenylphosphoryl)methane (dppom) and trans -1,2-bis(diphenylphosphoryl)ethylene (tdppoet) have been synthesised and characterized by infrared spectroscopy, and an X-ray diffraction study has been carried out on two of them, {SnPh 3 NO 3 } 2 dpaoe ( 1 ) and SnPh 2 (NO 3 ) 2 dppom ( 2 ). Both 1 and 2 crystallize in the triclinic space group P 1 , with unit-cell dimensions. 1 : a 12.810(8), b 11.938(6), c 10.394(4) A, α 97.92(4), β 90.00(5), γ 111.13(4)°, Z = 1, R = 0.0454; 2 : a 13.845(6), b 13.119(4), c 10.444(6) A, α 106.50(4), β 101.24(4), γ 91.33(4)°, Z = 2, R = 0.0504. The structure of 1 consists of binuclear monomeric units in which each tin atom is bound in a trigonal bipyramidal configuration to three phenyl rings in the equatorial plane and to the diarsine ligand and the nitrate group in the axial positions. In compound 2 the tin atom exhibits a pentagonal-bipyramidal coordination geometry with five oxygen atoms, two from the chelating dppom ligand and three from the two nitrate groups, around the pentagonal girdle, and the two phenyl groups at the apices of the bipyramid. The vibrational frequencies of the nitrate groups and of the diarsine and diphosphine ligands are discussed in the light of the X-ray results.

Hydrogen bonding in thiosemicarbazide

In a recent paper (Domiano, Fava Gasparri, Nardelli & Sgarabotto, 1969, DGNS) the crystal-structure analysis of thiosemicarbazide, carried out by photographic methods, was reported (final R=9 .9%) . The positions of the hydrogen atoms were postulated from consideration of the hybridization of the nitrogen atoms and the packing interactions, no direct determination of position being possible from the final difference synthesis. In order to obtain a more accurate structure analysis, suitable for the location of the hydrogen atoms, new data have been collected at room temperature with an automated Picker diffractometer.

Activation of unsaturated substrates by cobalt complexes. Crystal structure and reactivity of a complex of octacarbonyl dicobalt with N-methylbis(α,α-dimethylpropargyl)amine

Abstract A new complex of octacarbonyl dicobalt with N -methyl(α,α-dimethylpropargyl)amine was prepared and characterized by spectroscopic and X-ray diffraction methods. Each triple bond is coordinated to a hexacarbonyldicobalt fragment and each metal shows a pseudo-octahedral geometry. The structure of the free ligand having NH in place of N -methyl has also been determined for comparison. Thermal decomposition of the complex in toluene or in benzonitrile afforded a series of products, mainly resulting from the rearrangement of the original complex to a metallacyclic structure, able to incorporate either the acetylenic triple bond or carbon monoxide in the case of toluene and either the acetylenic or the nitrile triple bond in the case of benzonitrile. CN bond cleavage of the starting amine was observed as a side reaction. Catalytic reactions leading to benzonitrile incorporation were also observed. A cross experiment with a 1 1 mixture of diynes, either with or without geminal methyl groups α to triple bonds showed that for conformation reasons the metallacycle moiety mainly comes from the substrate containing geminal groups, whilst for steric reasons the other substrate is preferentially incorporated into the metallacycle.

Structural researches on metal complexes of polydentate ligands containing carbonyl and α-diimine moieties, part V. Heptacoordination in a manganese(II) complex of 2,6-diacetylpyridinebis(picolinoylhydrazone)

SummaryThe MnCl2 (H2 DIP) · 5H2O complex [H2DIP = 2,6-diacetyl-pyridinebis(picolinoylhydrazone)] has been synthesized and examined by i.r.-spectroscopy and x-ray diffractometry. Crystals are triclinic (P

X-Ray crystal structures of tetrakis(imidazolidine-2-thionato)copper(I) nitrate and dichloro-µ-imidazolidine-2-thionato-tris(imidazolidine-2-thionato)dicopper(I)

(P \bar 1)