Crystal and molecular structure of calcium 2,4,6,8-cyclooctatetraene-1, 2-dicarboxylate dihydrate

Calcium 2,4,6,8-cyclooctatetraene-1,2-dicarboxylate dihydrate, CaC₈H₆(COO)₂. 2H₂O, crystallizes in the triclinic space groupP¯1 (C _i ¹) with unit cell dimensions:a = 6·270(3),b = 7·767(4),c = 12·141(7) Å, = 91·10(2), = 100·21(2), = 99·76(2) °;V _c = 572·64 ų,Z = 2,D _m = 1·520(9),D _c = 1·544 g cm^–3. The anion has an approximate 2-fold axis of symmetry to which bond lengths, angles and dihedral angles conform within experimental error. The cyclooctatetraene ring has a tub shape, similar to that found in other cyclooctatetraene structures, with its average bond lengths of 1·46 Å and 1·34 Å for single and double bonds respectively in good agreement with earlier values for similar molecules. The Ca²⁺ cation is coordinated by eight oxygen atoms (six carboxylate, two water) in a distorted tetragonal antiprism with distances ranging from 2·30 to 3·07 Å. All hydrogen atoms were located; the water hydrogens form a layer-like network of hydrogen bonds linking the water and carboxylate oxygens approximately perpendicular to the z axis. The distances range from 2·74 to 2·96 Å.     

Pentacoordination in dichloro-N-2-methylthiophenyl-2′-pyridylmethyleneiminecopper(II)

Dichloro-N-2-methylthiophenyl-2-pyridylmethyleneiminecopper(II) is monoclinic:P2₁/c;a = 8·49(1),b = 10·80(1),c = 15·67(1) Å, = 92·0(3)·,Z = 4. The crystal structure has been determined at room temperature from three-dimensional X-ray photographic data and refined by differential methods with anisotropic thermal parameters to a finalR value of 8·1%. Cu(II) coordinates to two chlorine atoms (Cu-Cl = 2·255,2·443 Å) and to one sulphur (Cu-S = 2·341 Å) and to two nitrogen atoms (Cu-N = 2·011, 2·014 Å) from methylthiophenylpyridylmethyleneimine; this represents a distorted tetragonal pyramid with the organic molecule behaving as a tridentate ligand. Packing is determined by normal van der Waals contacts.     

Crystal structure of 3-methylrhodaninecopper(I) iodide

The crystal structure of the copper(I) complex has been determined by a three-dimensional X-ray analysis. The monoclinic unit cell, space groupP2₁/c,a = 4·195(1),b = 15·581(2),c = 13·885(2) Å and = 114·9(1) °, contains four formula-units. Intensities were collected on an automatic diffractometer. The structural parameters were refined by full-matrix least-squares methods to a conventionalR value of 0·07 for 1809 non-zero observed reflexions.In this complex, the copper atom is in tetrahedral coordination with three iodine atoms and the sulphur atom of the thiocarbonyl group of the ligand. The iodine atom is coordinated with three copper atoms. The distances are 2·683(2), 2·627(2) and 2·665(2) Å. The distances between neighbouring copper atoms are 3·008(3) and 2·960(3) Å and the corresponding angles are 68·44(6) and 68·02(6) °, suggesting weak copper-copper interactions in this complex.     

Crystal and molecular structure of diiodo-N,N,N′,N′-tetramethylthiuramdisulphidemercury(II)

The crystal and molecular structure of diiodo-N,N,N,N-tetramethylthiuramdisulphidemercury(II), HgI₂(S₂CN(CH₃)₂)₂, has been determined by a three-dimensional X-ray analysis. The compound crystallizes in the monoclinic space groupP2₁/c with the unit cell dimensionsa = 7·957 ± 4,b = 22·639 ± 7,c = 9·956 ± 6 Å and = 112·14 ± 5 °;Z = 4. Intensities were obtained with an automatic diffractometer. The structural parameters were refined by least-squares methods to a conventionalR factor of 0·044 for 1294 non-zero observed reflexions. The mercury is in distorted tetrahedral coordination with two iodine and two sulphur atoms. The Hg-I distances are 2.654 ± 2 and 2·661 ± 2 Å; the Hg-S distances are 2·651 ± 7 and 2·882 ± 7 Å. The thiuramdisulphide ligand consists of two planar units S₂CNC₂, nearly perpendicular to each other. Bond distances of the ligand are compared with distances in tetraalkylthiuram disulphide molecules and agree with infrared observations.The authors are grateful to Professor J. J. Steggerda for his continuous interest, and to Mr W. P. J. H. Bosman and Mr J. M. M. Smits for valuable assistance.     

Crystal and molecular structure of bis(2,2,6,6-tetramethylheptane-5-thiolo-3-onato)nickel(II)

The crystal structure of the nickel(II) chelate of the monothio derivative of 2,2,6,6-tetramethyl-heptane-3, 5-dione has been studied at room temperature by X-ray diffraction methods. The space group isP2₁/c and the crystal data area = 19·96(2),b = 10·25(1),c = 12·45(1) Å, = 102·17(5) °Z = 4,D _m = 1·22,D _c = 1·23 g cm^–3. Full-matrix least-squares refinement of atomic and anisotropic thermal parameters, using 2109 non-zero intensities obtained by counter methods, terminated with a conventionalR of 0·105. The nickel was found to be surrounded by acis arrangement of two oxygen and two sulphur atoms which is almost planar, but slightly distorted towards a tetrahedron. All the evidence obtained supports extensive delocalization in the chelate rings, and the entire molecule has pseudomm symmetry. Thecis, rather thantrans relationship of the ligand atoms may indicate weak S-S interaction.     

Crystal and molecular structure of chlorotris(monomethylthiourea)silver(I)

The crystal and molecular structure of chlorotris(monomethylthiourea)silver(I) has been solved and refined by full-matrix least-squares methods to a finalR of 0·039 from 1150 reflections measured by counter techniques at ambient room temperature. The crystals are orthorhombic:Pmcn, a = 14·824(2),b = 8·524(1),c = 12·671(1) Å,Z = 4,D _m = 1·68,D _c = 1·72 gcm^–3. The structure consists of independent, distorted tetrahedral Ag(I) moieties with only weak hydrogen bonds and/or van der Waals interactions between molecules. These molecules are packed in such a way that Ag, Cl and one entire monomethylthiourea ligand all lie in a crystallographic mirror plane, and the other two ligands are related by this mirror. This arrangement, plus the alternation of the Ag-Cl bond direction, leads to a non-polar sheet of Ag, Cl and monomethylthiourea groups with other monomethylthiourea groups protruding from either side of the sheet. Only N-HCl hydrogen bonds and van der Waals interactions exist between sheets. The Ag-S distance is somewhat long at 2·649(3) Å, as is one of the Ag-S distances at 2·665(3) Å. The other two Ag-S distances are 2·520(2) Å. The geometry of the complex makes it clear that the Ag-S bond is formed by donation of an electron pair from a sulfur sp² orbital.     

Crystal and molecular structure of 1-(2-aminoethyl)biguanide-isothiocyanato-copper(II) thiocyanate

The crystal structure of 1-(2-aminoethyl)biguanide-isothiocyanato-copper(II)thiocyanate, [Cu(aebg)(NCS)] (SCN) (aebg = NH₂. CH₂. CH₂. N=C(NH₂). NH. C(NH). NH₂) has been determined and refined by Fourier methods using three-dimensional X-ray data collected on a Weissenberg automatic diffractometer. The unit cell parameters are:a = 11·41(2),b = 8·81(2),c = 7·45(2) Å; = 87·6° (2); = 67·2° (2); = 70·1° (2);Z = 2.Assuming space group P¯1, the structure was refined down toR = 8·5 %. The coordination around Cu is slightly distorted square planar and concerns three N atoms from the aebg ligand (Cu-N = 1·988(8), 2·019(7), 1·963(5) Å) and the terminal N of an isothiocyanate group (Cu-N = 1·941(5) Å). Two unsymmetrical, long interactions (Cu-N = 3·367(7) and 2·947(7) Å), with the N atoms belonging to two NCS groupstrans with respect to the coordination plane, complete the coordination to a distorted octahedron. In the aebg ligand the double bonds are localized on the C-N groups, whose nitrogen atoms coordinate to the metal.This work was carried out with the aid of financial support from the Consiglio Nazionale delle Ricerche, Roma.     

Crystal and molecular structure ofcis-dicarbonyltetraphosphinechromium(O), [(CO)2(PH3)4Cr]

The crystal and molecular structure ofcis-dicarbonyltetraphosphinechromium(O), [(CO)₂(PH₃)₄Cr] has been determined by X-ray diffraction methods. The compound crystallizes in the monoclinic system: space groupC2/c,a = 6·968(6),b = 11·98(1),c = 12·87(1) Å, = 99·80(8) °,V= 1059(3) ų,Z=4,D _m = 1·534(5),D _x = 1·531(5) gcm^–3, diffraction symmetry 2/m. The structure was solved by conventional methods, and refined by least-squares techniques to an agreement factorR = 0·078. The chromium atoms lie on rotation diads, and thus the molecules must have at least the symmetry 2(C ₂); they were found to have, within the limits of accuracy, the even higher symmetrymm2 (C _2v ). There are two distinct independent Cr-P distances in the molecule, the Cr-P bonds where phosphorus istrans to carbonyl [2·338(4) Å] being significantly longer than those where phosphorus istrans to phosphine [2·282(4) Å]. This difference may be attributed to a difference in the back-bonding capabilities of the two types of ligands.We wish to thank Professor Dr E. O. Fischer for his stimulating interest in this work. Our thanks are due also to the Leibniz Rechenzentrum der Bayerischen Akademie der Wissenschaften for use of their computing facilities. This work would not have been possible without a generous grant from the Deutsche Forschungsgemeinschaft which is gratefully acknowledged.     

Stereochemistry of racemic hexamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-dienenickel(II) thiocyanate,C16H32N4Ni(SCN)2 · H2O

The diamagnetictrans-diene thiocyanate salt of the macrocyclic hexamethyl-1,4,8,11-tetraazacyclotetradecadienenickel(II) complex crystallizes in the triclinic system with unit cell dimensions:a = 7·334(4),b = 8·808(6),c = 21·04(2) Å; = 63·7(0·9), = 103·8(1·4), = 110·2(1·3) °; space groupP¯1;Z = 2. The positions of all 62 atoms of the formula unit C₁₆H₃₂N₄Ni(SCN)₂.H₂O have been determined and refined by least-squares methods toR= 0·071 for 3536 X-ray diffractometric reflections. The optical activity of the two amine groups yields a racemic isomer. The only local symmetry element of the macrocyclic complex is the twofold rotation axis with the N-H bonds oriented on the same side of the approximate ligand plane. Both the C(CH₃)₂ and the imine groups are in atrans-configuration in the ring. The space group ensures that the crystal is a racemate, containing equal numbers of both enantiomers. One of the (SCN)^– groups is at a distance Ni-S 3·28 Å, the other one is 4·65 Å. No rotational disorder of the CH₃ groups has been observed. The three C-H bonds of the CH₃ groups are in approximately antiprismatic orientations with respect to the three -bonds in the case of bonding to a C(sp³) atom. The average of the C(sp³)-C(sp²) bond lengths is 1·53 Å, and the mean value for the C(sp³)-C(sp²) bonds is 1·50 Å, with 3 = 0·03 to 0·04 Å. The distances N(sp²)-C(sp³) 1·47 Å and 1·48 Å are significantly longer than the bond lengths N(sp²)=C(sp²) of 1·28 and 1·30 Å.     

Crystal and molecular structure of di-μ-chloro(dicyandiamide)cadmium(II)

The crystal structure of di--chloro(dicyandiamide)cadmium(II) has been determined and refined by Fourier and least-squares methods toR = 0·037 using three-dimensional X-ray data collected at room-temperature on a single-crystal automated diffractometer. Crystal data are as follows:a = 10·796(7),b = 8·933(5),c = 6·847(3) Å, = 99·9(1) °,Z = 4; space groupP2₁/n. The cadmium atom is surrounded by four chlorine (Cu-Cl = 2·572, 2·607, 2·630, 2·647 Å) and two nitrogen atoms (Cd-N (nitrilic) = 2·358 Å; Cd-N (guanidic) = 2·430 Å) so that the whole polyhedron appears as a slightly distorted octahedron. The chlorine atoms form bridges between adjacent metal atoms so that the coordination octahedra are linked in chains running along [001]. These chains are joined together by dicyandiamide bridges.The authors wish to thank Dr. A. Immirzi (Politecnico di Milano) for the use of his compter programmes.     

Crystal and molecular structure of tetrakis(N,N′-diallylthiourea)nickel(II) iodide

Summary The crystal structure of tetrakis(N,N-diallylthiourea)nickel(II) iodide [Ni(C₇H₁₂N₂S)₄I₂] has been determined by a three-dimensional X-ray analysis. FinalR, after anisotropic least-squares refinement, is 8·8%. The crystals are tetragonal (P4/n):a = 11·24(1),c = 15·43(1) Å,Z = 2. Ni(II) is on a 4-fold axis; the coordination around it is flattened pyramidal and involves four sulphur atoms from four diallylthiourea molecules (Ni-S = 2·221 Å). Ni(II) is out of the plane through the sulphur atoms by 0·40 Å. Two I^- ions lie on opposite sides with respect to the nickel atom along the 4-fold axis, at distances Ni...I(1) = 3·74 Å, Ni...I(2) = 6·64 Å. The orientation of the allylthiourea molecules is determined mainly by a hydrogen bond formed by one nitrogen (N(1)) with the iodine which is nearer to the nickel.The authors are indebted to Prof. C. Furlani who kindly supplied the crystals of the compound.     

Structure analysis of twinned crystals of tris(N,N-di-n-butyldiselenocarbamato)nickel(IV) bromide

The crystal structure of tris(N,N-di-n-butyldiselenocarbamato)nickel(IV) bromide, Ni(Se₂CN-(C₄H₉)₂)₃Br, has been determined by three-dimensional X-ray methods. The Laue symmetry is 6/mmm, but the structure could be solved only in space groupP¯31c. The crystals were, therefore, regarded as being microtwinned on (001). The unit cell dimensions area =b = 14·69(3) andc = 10·91(3) Å. From integrated Weissenberg photographs, 307 non-zero symmetry-independent reflexions were measured photometrically. The structural parameters were refined by least-squares methods to a conventionalR factor of 0·10. The quadrivalent nickel atom is octahedrally coordinated by six selenium atoms. The Ni-Se distance is 2·391(5) Å; the Se-Se distance within one diselenocarbamate ligand is 3·00(1) Å; Se-Se distances between different ligands are 3·51(1), 3·52(1) and 3·55(1) Å.We thank Professor J. J. Steggerda for his continuous interest, and Mr J. M. M. Smits for valuable assistance.     

Crystal and molecular structure of benzylidenemalononitrile

Benzylidenemalononitrile, C₁₀H₆N₂ crystallizes in the monoclinic space group,P2₁/c;a = 9·385,b = 3·976,c = 22·152 Å, = 93·53 °,V _c = 825·03 ų,D _m = 1·231,D _c = 1·242 g cm^–3,Z= 4. The structure was solved by fitting cojointly an assumed molecular shape to both the near-origin peaks of the sharpened vector map and the distribution in the Harker (U,1/2,W) section, followed by trial-and-error establishment of the coordinates. The structure was then refined by full-matrix least squares, reducingR to 0·090 for data comprising 1412 reflexions (0·086, omitting 373 unobserved) from room temperature CuK Weissenberg photographs. Steric hindrance of the malononitrile group and a hydrogen atom in theortho position of the phenyl ring causes simultaneous expansion of the bond angles between the malononitrile group and the benzylidene group and rotations of these groups relative to each other. These constraints cause the two groups to be non-planar, the dihedral angle between their least-squares planes being 11·0 °.     

Crystal and molecular structure of bis(N,N-di-n-butyldithiocarbamato)copper(III) triiodide

The crystal and molecular structure of bis(N,N-di-n-butyldithiocarbamato)-copper (III) triiodide, Cu(S₂CN(C₄H₉)₂)₂ ⁺I₃ ^–, has been determined from a single-crystal X-ray diffraction study. The monoclinic unit cell, space groupP2₁/c,a = 14·026(6),b = 8·62(1),c = 25·015(9) Å, = 95·35(5) °, contains four formulaentities. Three-dimensional intensity data were obtained from Weissenberg photographs. Atomic parameters were refined by full-matrix least-squares methods to a conventionalR value of 0·083 for 950 independent non-zero reflexions. The structure contains two symmetry-independent cations. In both cations, the copper atom is in planar coordination with four sulphur atoms, the mean Cu(III)-S bond length being 2·22(2) Å. Cu(III)-S distances are about 0·08 Å less than Cu(II)-S distances in comparable complexes.     

Crystal and molecular structure of 2,5-dimethyl-3,4-diacetylfuran

The crystal and molecular structure of 2,5-dimethyl-3,4-diacetylfuran has been determined by direct methods using CuK. photographic data. Refinement by full-matrix least-squares methods gave a finalR factor of 0·097. The crystals are monoclinic: space groupP2₁/c,a =14·92(2),b = 4·09(1),c =16·68(3) Å and = 109·7(5) °;Z = 4. The furan ring of the molecule is planar, and the exocyclic atoms bound to the atoms of the ring lie close to the ring plane. The planes of the acetyl groups are tilted by 16 ° and 47 ° with respect to the ring plane. The exocyclic bond angles of this compound are significantly different from the equivalent angles in furan.     

Synthesis and crystal structure of two vanadium(V) hydroxylamido complexes with amino acid ligands

Two vanadium(V) hydroxylamido complexes with amino acid ligands including Alanine, [VO(NH₂O)₂(Ala)]·2H₂O, and Threonine, VO(NH₂O)₂(Thr), were synthesized and characterized by elemental analyses, IR spectrum, and single crystal X-ray diffraction. The two complexes are seven-coordinated with four nitrogen atoms and three oxygen atoms in pentagonal bipyramidal geometry. The different hydrogen bonds (N–H···O, O–H···O) observed in the two complexes result in the two-dimensional network structure. [VO(NH₂O)₂(Ala)]·2H₂O belongs to monoclinic: space group P2(1)/c, with a = 21.874(13) Å, b = 8.874(5) Å, c = 15.865(9) Å, = 100.423(8)°, V = 3029(3) ų, Z = 12, D _c = 1.678 g/cm³, (MoK) = 1.002 mm^–1, F (000) = 1584, and final R ₁ = 0.0375, wR ₂ = 0.0886 for observed reflections 1189 (IT > I> 2(I)). VO(NH₂O)₂(Thr) is rhombohedral: space group R-3, with a = 21.460(16) Å, b = 21.460(16) Å, c = 11.184(12) Å, = 120°, V = 4461(7) ų, Z = 18, D _c = 1.669 g/cm³, (MoK) = 1.012 mm^–1, F(000) = 2304, and final R ₁ = 0.0356, wR ₂ = 0.0924 for observed reflections 1306 (I > 2(I)).     

Crystal and molecular structure of bis-tetraphenylarsonium-tris-(cis-1,2-dicyano-1,2-ethylenedithiolato)Fe(IV)

The crystal structure of bis-tetraphenylarsonium-tris-(cis-1,2-dicyano-1,2-ethylenedithiolato)Fe(IV), [(C₆H₅)₃As]₂Fe[S₂C₂(CN)₂]₃, has been determined using 3154 independent, non-zero reflexions collected by counter techniques. The substance crystallizes in the monoclinic system: space groupI2/a,a = 20·153(8),b = 13·411(5),c = 21·497(8) Å and = 95·28(8) °;D _m = 1·41(2),D _c = 1·43 g cm^–3 andZ = 4. The structure consists of Ph₄As⁺ cations in general positions and tris-(cis-1,2-dicyano-1,2-ethylenediothiolato)Fe(IV) anions on two-fold axes. Although the coordination around the arsenic atom is tetrahedral, the overall symmetry of the cation is 1 (C ₁), probably because the phenyl rings are rotated to accommodate the requirements of packing. The coordination of the six sulphur atoms about the iron atom is trigonal antiprismatic, approximating closely to an octahedron: for any pair oftrans sulphur atoms, the S-Fe-S angle is about 171 °.     

Crystal and molecular structures of two polymeric organotin carboxylates,C5H12O2Sn and C5H9F3O2Sn

The crystal and molecular structures of trimethyltin(IV) acetate and trimethyltin(IV) trifluoroacetate have been determined from three-dimensional X-ray data collected by counter methods using MoK radiation. Both compounds crystallize in the orthorhombic space groupPnma withZ = 4. The acetate hasa = 10·516,b = 8·013,c = 9·706 Å and the trifluoroacetate hasa = 10·567,b = 9·237,c = 9·985 Å. ConventionalR-factors for the two compounds following least squares refinement are, for the acetate, 0·018 (for 731 reflexions) and, for the trifluoroacetate, 0·055 (for 460 reflexions) respectively. The compounds are isostructural and are polymeric with tin atoms linked by carboxylate bridges which are exactly planar. The tin atoms are in five-fold trigonal bipyramidal coordination with the methyl groups in the basal plane and oxygen atoms at the apices. Sn-O interatomic distances are, for the acetate, 2·205(3) and 2·391(4) Å, and for the trifluoroacetate, 2·18(1) and 2·46(2) Å.     

Synthesis and structure of [Ca(triethyleneglycol)2](NO3)2·H2O

Crystallization of calcium nitrate from a toluene solution of triethyleneglycol (= 2,2-[1,2-ethanediylbis(oxy)]-bisethanol) resulted in the formation of the 1:2 solvate [Ca(triethyleneglycol)₂](NO₃)₂·H₂O. [Ca(C₆H₁₄O₄)₂](NO₃)₂·H₂O is monoclinic, P2₁/c, a = 15.775(1), b = 8.660(2), c = 16.342(1) Å, = 91.239(7)°, V = 2232.1(6) ų, Z = 4, and D _c = 1.429 g cm^–3. The eight-coordinate calcium has square antiprismatic geometry with two triethyleneglycol molecules straddling the metal center. The nitrate anions and water of crystallization are involved in hydrogen bonding with the alcoholic hydrogen atoms.     

Crystal and molecular structures of the orthorhombic and monoclinic isomers of catena-di-μ-chloro-semicarbazidecopper(II)

The crystal structures of two isomeric complex compounds of formula [Cu(Cl)₂(NH₂NHCONH₂)] have been determined by X-ray diffraction methods. The orthorhombic isomer has space groupPna2₁ and unit cell constants:a = 6·91(1),b = 8·30(1),c = 10·24(1) Å;Z = 4. The monoclinic isomer has space groupP2₁/c and unit cell constants:a = 6·91(1),b = 8·30(1),c = 11·32(1) Å, = 117·1(2)°;Z = 4. In both complexes coordination around copper is octahedral, with chains of coordination polyhedra along [100]. In the monoclinic compound, the two semicarbazide molecules, which are present in two adjacent octahedra along the chain, have the oxygen and nitrogen atoms in thetrans configuration, one with respect to the other, and are correlated by a centre of symmetry. In the orthorhombic compound, the two semicarbazide molecules are in thecis configuration and there is no centre of symmetry. In both compounds packing is determined by the NH···Cl and NH···O hydrogen bonds which join the chains together.The authors are indebted to Mr M. Lanfranchi who prepared the compounds and to Dr A. Immirzi who made abailable his computer programs.