M. F. C. Ladd

Crystallographic and spectroscopic studies on ethylenediaminetetraacetic acid (edta)

Abstractβ-ethylenediaminetetraacetic acid crystallizes in the monoclinic system:a = 13·273(4),b = 5·575(7),c = 16·110(6) Å, β = 96·26(3),Z = 4,C2/c. The structure has been determined by direct methods with CuKα diffractometer data, and refined by full-matrix least squares toR = 0·057 for 755 observed reflexions.The molecule exists in acis conformation and possesses two-fold symmetry, the diad axis passing through the central C—C bond. The nitrogen atom is protonated, and takes part in a bifurcated intramolecular hydrogen bond. A short (2·46 Å) hydrogen bond links the oxygen atoms of adjacent molecules.

Substituted phenols as ligands III: Crystal and molecular structure of bis(4-formyl-2-methoxyphenolato)bis(pyridine)copper(II) monohydrate

Bis(4-formyl-2-methoxyphenolato)bis(pyridine)copper(II) monohydrate crystallizes in the triclinic system:a = 10·432,b = 9·342,c = 13·799 Å, α = 103·75, β = 100·53, γ = 100·81 °,Z = 2, space groupP¯1.The structure was determined by Fourier methods with Cukα diffractometer data, and refined by a combination of block-diagonal and full-matrix least squares toR = 0·068 for 2430 observed reflexions.The copper atoms occupy the special positions 0, 0, 0 and 0,1/2, 1/2; hence, both molecules are centrosymmetric. Both the methoxy and phenolic oxygen atoms of the phenolate ions coordinate to the metal. These, together with coordinated nitrogen atoms from the pyridine molecules, give the copper atoms a six-fold coordination.Hydrogen bonding between a water molecule and the phenolic oxygen atoms of adjacent molecules results in chains of molecules linked approximately along [011].

Crystallographic studies of dihalogeno-tetramethylethylenediamine complexes of zinc, cadmium, and mercury. II: Crystal and molecular structure of dibromo-(N,N,N′,N′-tetramethylethylenediamine) cadmium(II)

The crystal structure of dibromo-(N,N,N′N′-tetramethylethylenediamine) cadmium(II), C6H16Br2CdN2, has been determined from 1890 reflections measured on a Siemens four-circle diffractometer using the ω/2θ scan technique and CuKα. radiation. The crystals are monoclinic:P21/c,a = 7.532(2),b = 10.689(6),c = 14.674(7) Å, β = 91.91(7) β andZ = 4. The structure was solved by Fourier methods and refined by full-matrix least squares to a finalR (conventional) of 6.1%. Anisotropic thermal parameters were evaluated for the non-hydrogen atoms, but the hydrogen atoms were assigned the average isotropic thermal parameter of the carbon atoms. Each cadmium atom is octahedrally coordinated by two pairs of bromine atoms, giving average Cd-Br bond lengths of 2.753(2) and 2.844(2) Å, and a pair of nitrogen atoms in thecis configuration with respect to cadmium, with an average Cd-N bond length of 2.46(1) Å. The average Br-Cd-Br and N-Cd-Br angles are 88.1 and 90.6 ° respectively. The bromine atoms provide bridges to the metal atoms, resulting in a chain-like structure with the chain direction approximately parallel to thex-axis.

Crystal and molecular structure of 3-(2-(1,10-phenanthrolyl))-5,6-diphenyl-1,2,4-triazine-chloroaquotriphenyltin(IV) (1:1)

Abstract3-(2-(1,10-Phenanthrolyl))-5,6-diphenyl-1,2,4-triazine-chloroaquotriphenyl-tin(IV) (1:1) crystallizes in the orthorhombic system:a=19.195,b=9.144,c=21.642 Å,Z=4, space groupPca21 (No. 29). The structure was determined using the procedure for difference structures (Dirdir) with CuKα diffractometer data, and refined by block-diagonal least squares toR=0.031 for 3287 observed reflections. The tin atom is 5-coordinate with the three phenyl groups forming the equatorial plane. A chlorine atom and a water molecule complete the coordination. The triazine moiety does not coordinate directly to the metal atom. The only interaction is due to two N ⋯ H-O hydrogen bonds formed between two nitrogen atoms from the ligand and the water molecule.

Crystallographic and spectroscopic studies on ethylenediaminetetraacetic acid (edta) III. Crystal and molecular structure of α-edta and infrared studies on α- and β-edta

Abstractα-Edta is monoclinic:C2/c,a= 11.812,b = 9.647,c = 12.970 Å, β = 113.23 ° andZ = 4. The structure has been determined by direct methods with CuKα diffractometer data, and refined by full-matrix least squares toR = 7.2% for 737 observed reflexions. The molecule exists as a zwitter ion in acis conformation, and possesses crystallographic two-fold symmetry. The nitrogen atom is protonated and takes part in hydrogen bonding. α-Edta is hydrated, in this specimen, refinement indicated a value of 0.39 H2O per molecule of edta. A short (2.47 Å) hydrogen bond links oxygen atoms in adjacent molecules. Infrared spectra are reported for both α-edta and β-edta; the results are discussed in terms of the crystal structures. The formulation of α-edta with 0.39 mole H2O is explained.

Substituted phenols as ligands VI: Crystal and molecular structure of bis(2-methoxy-4-nitrophenolato)N,N,N′N′-tetramethyl-ethylenediamine copper(II) dihydrate

Bis(2 — methoxy — 4 — nitrophenolato)N,N,N′,N′ — tetramethylethylenediamine copper(II) dihydrate crystallizes in the orthorhombic systema = 16.160,b = 18.538,c = 8.263 Å,Z = 4, space groupPbcn. The structure was determined by Fourier methods with CuKα diffractometer data, and refined by full-matrix least squares toR = 0.052 for 1585 observed reflexions. The molecules exhibit crystallographic two-fold symmetry with the diad axis passing through both the copper atom and the center of the carbon-carbon bond of the tetramethylethylenediamine moiety. Both the methoxy and phenolic oxygen atoms coordinate to the metal, as does the nitrogen atom of the tetramethylethylenediamine group, giving the copper atom sixfold coordination. The oxygen atoms of a phenolic group and one nitro group are involved in hydrogen bonds with the water molecules, resulting in a pairing of molecules about centers of symmetry. The solid-state electronic reflectance spectrum of the compound indicates a Type 1 molecule (Bullock et al., 1974), and this has been confirmed by the crystal structure analysis.

Structures of bis(salicylaldoximato)- and bis(5-chlorosalicylaldoximato)nitrosylcobalt, examples of nitrosyls containing a bent Co-N-O group

The crystal and molecular structures of [Co(NO)(salox)2] and [Co(NO)(5-Clsalox)2], where saloxH is salicylaldoxime and 5-ClsaloxH is its 5-chloro derivative, have been determined. The unsubstituted nitrosyl crystallizes in the orthorhombic system,a=11.557,b=15.333,c=8.245 Å,Z=4, space groupPna21. The structure was determined by theDIRDIF difference structure factors method, using MoKα diffractometer data, and refined by full-matrix least squares toR=0.055 for 685 observed reflexions. The 5-chloro analogue crystallizes in the monoclinic system,a=8.553,b=12.510,c=15.702 Å, β=102.84°,Z=4, space groupP21/c. This structure was determined by the heavy-atom method, using MoKα diffractometer data, and refined by full-matrix least squares toR=0.043 for 2107 observed reflections. In both compounds, the molecule excluding the nitrosyl group is approximately planar. The cobalt atom is 5-coordinate in an essentially square pyramidal arrangement with the basal plane defined bytrans bidentate oximato ligands between which are strong hydrogen bonds. The nitrosyl group occupies the apical position, and the Co-N-O angles and the N-O bond lengths are 116(2)° and 1.48(3) Å ([Co(NO)(salox)2]), and 123.4(3)° and 1.070(5) Å ([Co(NO)(5-Clsalox)2]). The more acute angle and unusually long N-O bond of [Co(NO)(salox)2] may be due to disorder and/or an interaction between the NO oxygen atom and one of the oxime groups.

Structure of (1,2-diaminoethane) (1-[[2-[(2-aminoethyl) imino] propyl] thio]-2-propanone) nickel(II) nitrate

A single crystal X-ray investigation of the purple nickel (II) complex Ni[L(en)](NO3)2, produced by condensation of 1,2-diaminoethane (en) with the thiodiketone S(CH2COCH3)2 in the presence of nickel (II) nitrate (L is NH2(CH2)2N=C(CH3)CH2SCH2COCH3), shows that the metal ions are six coordinate. The new ligand L is tetradentate, with the N,N and S donor atoms arranged meridionally, and the coordination shell completed by the carbonyl oxygen atom of L and the nitrogen atoms of 1,2-diaminoethane. Metal-ligand bond distances are Ni-N: 2.08 av. (en), 2.10 and 2.05 (NH2 and N=C respectively of L); Ni-O, 2.16; Ni-S, 2.45 Å. There is considerable angular distortion from regular octahedral values of the bond angles at nickel. The crystals are monoclinic,P21/c (No. 14),a=12.433(2),b=11.709(1),c=13.150(2) Å,β=103.93(1)°,Vc=1858.2(4) Å3. The structure was solved by the heavy-atom method and refined by full-matrix least squares to anR value of 0.055 for 3633 reflections.

Crystal and molecular structure of 2-bromobenzo[b]indeno[1,2-e]pyran

Abstract2-bromobenzo[b]indeno[1,2-e]pyran crystallizes in the monoclinic system: space groupP21/c,a = 7·508,b = 5·959,c= 26·172 Å, β = 92·55 °. The structure has been determined by the heavy-atom method and refined by full-matrix least squares toR = 0·072 for 1027 observed reflections.The molecule is non-planar; the maximum deviations from the best plane occur at both ends of the length of the molecule, which results in distortion of the central portion from the expected geometry. The closest approach of two molecules, those related by a 21 axis, is 3·5 Å.

Synthesis, spectroscopy, and structures of 2-bromo-1-bromoimino-3-oxo-isoindoline(III) and 1-bromoimino-3-oxoisoindoline(IV)

The title compounds have been synthesized, characterized by spectroscopic and analytical methods, and the complete structure of (IV) determined by single-crystal X-ray methods. Compound (IV) is monoclinic:a=13.891(3),b=4.935(2),c=12.499(2)Å,β=112.10(1) deg,P21/n,Z=4. The structure was determined by the heavy-atom method, and refined by full-matrix least squares onF toR=4.6%, with 1283 reflexions for whichI≥3σ (I). The structure (IV) was confirmed, and the molecule was shown to be planar to within 0.01 Å.