The crystal structure of a binuclear cobalt(II) complex of a macrocyclic ligand

1975 ◽  
Vol 28 (12) ◽  
pp. 2607 ◽  
Author(s):  
BF Hoskins ◽  
GA Williams

The crystal and molecular structure of LCo2Br2,CH3OH (where LH2 represents the macrocycle obtained by condensation of two molecules each of propane-1,3-diamine and 2-hydroxy-5-methyl-isophthalaldehyde) has been determined by single-crystal X-ray diffraction techniques. The compound crystallizes in the monoclinic space group P21/c with two molecules in a cell of dimensions a 9.8723(5), b 16.891(1), c 8.0745(5)Ǻ and 102.06(1)�. Counter methods were used to collect the 2004 independent reflections above background and the structure was refined by least-squares methods to a conventional R-factor of 0.049. The structure is molecular, consisting of discrete binuclear units LCo2Br2,CH3OH, containing two cobalt(II) atoms separated by 3.158(2) Ǻ. Each cobalt atom is in an identical pseudo-square-pyramidal environment, in agreement with the conclusion drawn from the electronic spectrum of the complex, with an N2O2 basal plane and a bromine atom coordinated at the apex. The methanol molecule is disordered and partially occupies the sixth coordination site of each cobalt, with a long bond of 2.503(9) Ǻ between the cobalt and the methanol oxygen atom. The central carbon atom of the propane-1,3-diamine residue is also disordered, occupying partially each of two positions.


1981 ◽  
Vol 34 (1) ◽  
pp. 65 ◽  
Author(s):  
GA Williams ◽  
R Robson

The crystal and molecular structure of LCO2 [S2P(OEt)2]2 (where L is a binucleating ligand derived from the macrocycle LH2 formed by condensation of two molecules each of propane-1,3-diamine and 2-hydroxy-5-methylisophthalaldehyde) has been determined by single-crystal X-ray diffraction techniques at 295 K. The compound crystallizes in the triclinic space group Pī with two molecules in a cell of dimensions a 18.644(6), b 11.694(4), c 9.487(4) �, α 84.99(3), β 82.61(3), γ 73.48(2)�. Automatic diffractometry has provided significant Bragg intensities for 2799 independent reflections and the structure has been refined by least-squares methods to R 0.054. The structure is molecular, consisting of discrete binuclear units LCo2[S2P(OEt)2]2. The two centrosymmetric molecules in the unit cell are crystallographically unique but essentially chemically similar. The two cobalt(11) atoms in each molecule are separated by 3.075(2) and 3.072(2) �. Each cobalt atom is in an octahedral environment, with an N2O2 equatorial plane and two sulfur atoms of bridging dithiophosphate ligands in the axial positions. The Co-S bonds are the longest yet observed [2,680(3), 2.652(3), 2.642(3), 2.623(3) �]. The cobalt(11) centres are high spin, with �eff 4.53 BM per cobalt atom. The macrocyclic ligand deviates slightly from planarity. The forces exerted both by the ligand L on associated metal atoms, and by axial ligands on the macrocycle, are discussed.



1975 ◽  
Vol 28 (12) ◽  
pp. 2593 ◽  
Author(s):  
BF Hoskins ◽  
GA Williams

The compound Lco2Br3,2H2O (where L is a binucleating ligand derived from the macrocycle LH2 formed by condensation of two molecules each of propane-1,3-diamine and 2-hydroxy-5- methylisophthalaldehyde) was found to occur in two crystalline forms. The structures of both have been determined by single-crystal X-ray diffraction techniques, revealing that each corresponds to a different geometrical isomer of composition Lco2Br3,2H2O. Each structure was determined by the conventional Patterson-Fourier method and refined by a least-squares procedure, with only the Co, Br, N and O atoms being refined anisotropically. The first form, designated the A-isomer, crystallizes in the orthorhombic space group Pn21a with four formula units in a cell of dimensions a 15.173(1), b 17.370(2) and c 10.493(1) Ǻ. The structure refined to a conventional R-factor of 0.074 by means of 1883 unique reflections collected by counter methods. The second form, or B-isomer, crystallizes in the monoclinic space group P21 with two formula units in a cell of dimen- sions a 10.676(1), b 15.235(2), c 9.304(1) Ǻ and β 111.83(2)°. The structure refined to a conventional R-factor of 0.101 by means of 2006 independent reflections collected by counter methods. Both isomers are composed of discrete bromide anions together with discrete binuclear cations of com- position [Lco2Br2,2H2O]+, each containing one cobalt(II) and one cobalt(III) atom with a Co...Co distance of 3.13 Ǻ. In both isomers the cobalt atoms are in octahedral environments. In the A-isomer two bromine atoms are bonded to the cobalt(III) atom in positions perpendicular to the ligand N2O2 donor plane, with the two water molecules occupying similar positions about the cobalt((II). But in the B-isomer, one water molecule and one bromine atom are bonded to each of the cobalt(III) and the cobalt((II) atoms in the comparable positions. In both structures the ionic bromide is involved in a hydrogen-bonding scheme with the coordinated water molecules.



1979 ◽  
Vol 57 (23) ◽  
pp. 3157-3159 ◽  
Author(s):  
Doris Margaret Thompson ◽  
Ian David Brindle ◽  
Mary Frances Richardson

The crystal structure of (E)-6-(bromomethylene)-5,6-dihydro-4,4-dimethyl-2-phenyl-4H-1,3,4-oxadiazinium bromide has been determined by single crystal X-ray diffraction methods. The crystals are monoclinic, space group P21/c, with a = 12.002(5), b = 6.414(4), c = 17.881(7) Å, β = 101.42(7)°, and Z = 4 formula units of C12H14N2OBr2. The structure was refined by full-matrix least-squares analysis to a conventional R-factor of 0.0491 for 1019 observed reflections. The oxadiazinium ring is in the half-chair form, with the methylene group out of the plane defined by the other five atoms. The C—O bond distances in the ring are somewhat shorter than the distance observed for a carbon–oxygen single bond, suggesting that some delocalization of electron density occurs over part of the ring.



1971 ◽  
Vol 49 (3) ◽  
pp. 468-476 ◽  
Author(s):  
Lilian Y. Y. Chan ◽  
F. W. B. Einstein

The crystal structure of potassium hydrogen di-iodate (bi-iodate) KIO3.HIO3 was determined from three dimensional X-ray data collected by counter methods. The structure was refined by full-matrix least-squares techniques to a conventional R factor of 5.0 % for the 1392 observed reflexions. The salt crystallizes in the monoclinic space group P21/c with eight formula units in a cell of dimension a = 7.028(1) Å, b = 8.203(1) Å, c = 21.841(3) Å, β = 98.03(1)°.The iodate units are all basically pyramidal; weak interionic I—O contacts complete a very distorted octahedral environment around three iodine atoms. There is a capped octahedral (7-coordinate) environment around the remaining iodine atom. The I—O bonds are in the range 1.75–1.82 Å and the I—OH bonds are 1.91 and 1.95 Å, variations in length can be correlated with differences in the degree of involvement in (a) hydrogen bonding and (b) interaction with adjacent iodine atoms.



1986 ◽  
Vol 51 (11) ◽  
pp. 2521-2527 ◽  
Author(s):  
Jan Lokaj ◽  
Eleonóra Kellö ◽  
Viktor Kettmann ◽  
Viktor Vrábel ◽  
Vladimír Rattay

The crystal and molecular structure of SnBu2(pmdtc)2 has been solved by X-ray diffraction methods and refined by a block-diagonal least-squares procedure to R = 0.083 for 895 observed reflections. Monoclinic, space group C2, a = 19.893(6), b = 7.773(8), c = 12.947(8) . 10-10 m, β = 129.07(5)°, Z = 2, C20H38N2S4Sn. Measured and calculated densities are Dm = 1.38(2), Dc = 1.36 Mg m-3. Sn atom, placed on the twofold axes, is coordinated with four S atoms in the distances Sn-S 2.966(6) and 2.476(3) . 10-10 m. Coordination polyhedron is a strongly distorted octahedron. Ligand S2CN is planar.



1998 ◽  
Vol 51 (9) ◽  
pp. 867 ◽  
Author(s):  
Daniel E. Lynch ◽  
Lisa C. Thomas ◽  
Graham Smith ◽  
Karl A. Byriel ◽  
Colin H. L. Kennard

The crystal structure of the 1 : 1 adduct of N-methylaniline with 5-nitrofuran-2-carboxylic acid has been determined by single-crystal X-ray diffraction. Crystals are monoclinic, space group P21/c with Z 4 in a cell of dimensions a 8·467(5), b 6·106(2), c 23·95(1) Å, β 94·48(3)°. The molecules associate in a tetrameric, proton-transfer formation which has potential as a new supramolecular synthon.



1999 ◽  
Vol 52 (4) ◽  
pp. 325 ◽  
Author(s):  
Graham Smith ◽  
Colin H. L. Kennard ◽  
Karl A. Byriel

Silver(I) anthranilate, [Ag2(C7H6NO2)2]n, was isolated as the major constituent in the attempted preparation of the adduct of anthranilic acid (2-aminobenzoic acid) with silver(I) p-toluenesulfonate and its structure has been determined by using single-crystal X-ray diffraction. Crystals of the complex are monoclinic, space group P 21/n, with two dimers in a cell of dimensions a 5·3516(8), b 4·9746(2), c 25·386(5) Å, β 91· 547(8)°. The complex repeating unit comprises a distorted centrosymmetric biscarboxylato(-O,O′)-bridged dimer [Ag−O, 2·223, 2·409(4) Å; Ag---Ag 2·9128(9) Å] but has, in addition, a third bond to an adjacent amine nitrogen [Ag−N, 2·301(5) Å], which extends the structure into a zigzag chain polymer. The stereochemistry about each Ag centre is distorted trigonal planar [angle range, 89·9−142·9(2)°]. Relatively short inter-dimer Ag---Ag separations [2·989(1) Å] are also present.



1975 ◽  
Vol 53 (18) ◽  
pp. 2707-2713 ◽  
Author(s):  
Debbie Allen ◽  
Colin James Lyne Lock ◽  
Graham Turner ◽  
John Powell

The crystal and molecular structures of pentane-2,4-dionato-(2,3,5,6-tetrahapto-2,3-dicarbomethoxo[2.2.1]bicycloheptadienerhodium(I), Rh(C5H7O2)(C7H6(CO2CH3)2), have been measured by single crystal X-ray diffraction. The orange crystals are monoclinic, space group P21/c, Z = 4, a = 9.245(4), b = 9.003(4), c = 21.680(15) Å, β = 113.41(5)°. The calculated and observed densities are 1.645 and 1.642(5) respectively. Intensity data were collected on a Syntex [Formula: see text] diffractometer and a full matrix least squares refinement on 3010 observed reflections leads to a conventional R = 0.0660. The structure can be considered as a roughly square planar arrangement of ligands around the rhodium atom composed of two β-ketoenolate oxygen atoms (Rh—O, 2.037(5) and 2.025(5) Å ) and the centers of the two ethylenic groups. The Rh—C distances for the olefin group attached to the two carbomethoxo groups, 2.117(8), 2.108(8) Å, appear to be slightly larger than those for the other olefinic group, 2.087(7), 2.082(6), and the corresponding C=C distances of 1.375(10) and 1.410(9) Å are different at the 95% confidence level.



1975 ◽  
Vol 53 (22) ◽  
pp. 3383-3387 ◽  
Author(s):  
Joseph Hubert ◽  
André L. Beauchamp ◽  
Roland Rivest

The crystal and molecular structure of dithiocyanato(triphenylarsine)mercury(II) has been determined from X-ray diffraction data. The crystals are monoclinic, space group P21/c, with a = 10.290(7), b = 21.199(23), c = 10.719(7) Å, β = 112.00(2)°, and Z = 4. The structure has been solved by the heavy-atom method and refined by block-diagonal least-squares calculations. The agreement factor R obtained for 2607 'observed' reflections is 0.030. The crystal consists of single molecules. The 'characteristic' coordination number of mercury is three, with two sulfur and one arsenic atoms at the apexes of a triangle. The nitrogen atoms of the thiocyanate groups are at 2.67 and 2.74 Å from the adjoining mercury atoms and therefore link the different molecules together.



1979 ◽  
Vol 57 (2) ◽  
pp. 174-179 ◽  
Author(s):  
A. Wallace Cordes ◽  
Paul F. Schubert ◽  
Richard T. Oakley

The crystal structure of 1,4-diphenyl-2,2′,3,3′,5,5′,6,6′-octamethylcyclo-1,4-diphospha-2,3,5,6-tetrasilahexane, (PhPSi2Me4)2, has been determined by single crystal X-ray diffraction. The crystals are monoclinic, space group P21/c, with a = 9.866(1), b = 11.921(1), and c = 11.324(2) Å, β = 104.31(1)°, Z = 2, and ρcalcd = 1.15 g/cm3. The structure was solved by direct methods and was refined by full-matrix least-squares procedures to a final R of 0.060 and Rw of 0.078, for 1173 reflections with intensities greater than 3σ. The (PhPSi2Me4)2 molecule lies on a crystallographic centre of symmetry, and the six-membered P2Si4 ring has a chair conformation with equatorial phenyl groups. The endocyclic angles at P (104.4(1)°) and Si (104.9(2)°) are intermediate between those found in cyclic hexaphosphine and hexasilane molecules, and the Si—Si and P—Si distances of 2.345(3) and 2.252(4) Å, respectively, correspond to single bond lengths, with no appreciable evidence for secondary pπ → dπ bonding between phosphorus and silicon. The Si—C (1.867(8) Å) and P—C (1.828(7) Å) bond lengths are also normal. The variations in the Si—P—C (101.6(2)°, 108.6(2)°), P—Si—C (range 106.2(3)–120.0(3)°), and Si—Si—C (range 105.8(3)–113.7(3)°) angles indicate that the positions of the exocyclic methyl and phenyl groups are influenced by both intra- and intermolecular steric forces.



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