Bernard F. Hoskins

A new type of interpenetration involving enmeshed independent square grid sheets. The structure of diaquabis-(4,4′-bipyridine)zinc hexafluorosilicate

Zn(4,4′-bipy)2SiF6·2H2O (4,4′-bipy = 4,4′-bipyridine) consists of two perpendicular and equivalent stacks of infinite, essentially square grid [Zn(H2O)2(4,4′-bipy)2]n2n+ sheets, which interpenetrate so that any particular sheet has an infinite number of perpendicular ones enmeshed or concatenated with it.

Ni(tpt)(NO3)2—A Three-Dimensional Network with the Exceptional (12,3) Topology: A Self-Entangled Single Net

The shortest circuits in the three-dimensional network with (12,3) topology of solvated Ni(tpt)(NO3 )2 pass through one another (see picture). This network based upon interlinked double helices occupies a unique position in the set of (n,3) nets. tpt=tri-4-pyridyl-1,3,5-triazine.

Structural chemistry of organotin carboxylates: II. The crystal structure of the dicarboxylato tetraorganodistannoxane:{sunBu2Sn(O2CC5H4N)]2O}2☆

Abstract The crystal structure determination of the compound {[nBu2Sn(2-pic)]2O}2 (2-pic = O2CC5H4N) has revealed the presence of two distinct tin atom geometrics in the dicarboxylato tetraorganostannoxane structure. The centrosymmetric dimer also features two unique carboxylate groups, one of which bridges two tin centres via one oxygen atom only (the pendant oxygen atom is not coordinated to tin) and the other carboxylate functions essentially in the monodentate mode. One tin atom is six coordinate, and the other is seven coordinate by virtue of weak but significant intramolecular interactions. The two tin atom environments are best described as being based on distorted octahedral and pentagonal bipyramidal geometries, respectively. The 2-pyridinecarboxylate ligands introduce a major structural change in the dicarboxylato tetraorganostannoxane structure as a result of the formation of SnN bonds. In solution, 119Sn NMR spectroscopy indicates the presence of two distinct hexacoordinate tin centres. Crystals are orthorhombic with space group Pbca and unit cell dimensions a 15.760(2), b 18.208(3) and c 22.369(2) A. The structure was refined by a full-matrix least-squares procedure to final R = 0.035 for 3665 reflections with I > - 2.5σ (I).

Structures of [Ag(tcm)], [Ag(tcm)(phz)1/2] and [Ag(tcm)(pyz)] (tcm=tricyanomethanide, C(CN)3-, phz=phenazine, pyz=pyrazine)

The topologically unique sheet structure of [Ag(tcm)] [tcm=the tricyanomethanide ion, C(CN)3-] is retained in the derivative [Ag(tcm)(phz)1/2] (phz=phenazine). The sheet structure is composite, consisting of two independent hexagonal grid nets which are corrugated so as to allow one to interpenetrate the other. The Ag+ ion is three-coordinate and provides half the three-connecting nodes of the hexagonal grid net, the others being provided by the tcm central carbon. [Ag(tcm)(phz)1/2] contains essentially the same composite double sheets linked together by phenazine units that bridge between silver centres which thereby become four-coordinate. The topology of [Ag(tcm)(pyz)] (pyz=pyrazine) is very different; in this case the Ag(tcm) component forms a planar, non-corrugated hexagonal grid and each such sheet is connected on both sides to neighbouring sheets by pyrazine bridging ligands whereby the silver becomes five-coordinate and trigonal bipyramidal. Two such 3,5-connected three-dimensional nets then interpenetrate.

A wellsian ‘three-dimensional’ racemate: eight interpenetrating, enantiomorphic (10,3)-a nets, four right- and four left-handed

The crystal structure of solvated [Zn(tpt)2/3(SiF6)(H2O)2(MeOH)][tpt = 2,4,6-tris(4-pyridyl)-1,3,5-triazine] is comprised of eight independent [Zn3(tpt)2]n networks with the (10,3)-a topology, four of one handedness and four of the other, which interpenetrate in a remarkable way, aspects of which were postulated by A. F. Wells almost twenty years ago.

Complexes of binucleating ligands. VIII. The preparation, structure and properties of some mixed valence cobalt(II)—cobalt(III) complexes of a macrocyclic binucleating ligand

Abstract The complex LCo2Br2·CH3OH has been isolated, where LH2 represents the macrocyclic tetrakis-Schiff base obtained by condensation of two molecules each of 1,3-diaminopropane and 2-hydroxy-5-methylisophthalaldehyde and L represents the derived dianion which behaves as a macrocyclic binucleating ligand. By oxidation of LCo2Br2·CH3OH with bromine under a variety of conditions the following products were isolated: LCo2Br3·H2O, two isomeric forms of LCo2Br3·2H2O, LCo2Br4·CH3OH, LCo2Br5·2CH3 OH, LCo2Br8·4CH3OH, (LH)CoBr6·2H2O and (LH4) Br6. Crystals of LCo2Br5·2CH3OH have been shown by X-ray diffraction methods to consist of binuclear [LCo(II)Co(III)Br2(CH3OH)2]+ cations, in which both metal centres are essentially octahedral, and tribromide anions. LCo2Br3·H2O, the two isomeric forms of LCo2Br3·2H2O and LCo2Br4·CH3OH are assigned the binuclear Co(II)Co(III) formulations, [LCo(II)Co(III)Br2(H2O)+Br−, [LCo(II)Co(III) Br2(H2O)2]+Br− in two geometrically isomeric forms and {[LCo(II)Co(III)Br2(CH3OH)]+}2Br−(Br3−) respectively, in which the cobalt(III) centres are six coordinate and low spin and the cobalt(II) centres are high spin and either five or six coordinate. LCo2Br8·4CH3OH is diamagnetic with a binuclear Co(III)Co(III) structure and is unstable in the solid, liberating bromine and regenerating the paramagnetic Co(II)Co(III) binuclear unit. (LH4)Br6 formulated as (LH42+) (Br3−)2, is the first example of a metal-free derivative of the macrocycle and can now be isolated from a metal-free condensation reaction of the dialdehyde and diamine components. Crystals of LCo2Br5·2CH3OH are orthorhombic with cell dimensions a = 17.78, b = 37.74 and c = 19.79 A, space group Pbca and Z = 16. Counter methods were used to collect 1993 reflections above background. Despite rapid decomposition of the crystal during data collection, the structural framework was ascertained readily and the structure refined to the limit of accuracy allowed by the quality of the data, using a least-squares method with isotropic temperature factors, to the somewhat high value of R 0.15.

α-Polonium coordination networks constructed from bis(imidazole) ligands

Two types of bis(imidazole) ligands – 1,4-bis(imidazol-1-ylmethyl)benzene (bix) and 1,4-bis(imidazolyl)-2-butyne (bib) – have been used to bridge octahedral metal centres and form simple cubic networks. Crystal structures of Cd(bix)3(ClO4)2, Cd(bix)3(NO3)2, Zn(bib)3(BF4)2 and Co(bib)3(NO3)2 reveal that all possess the α-polonium topology and are triply interpenetrating.

Structural features of group V A xanthates. The crystal and molecular structures of tris(O-isopropylxanthatoarsenic(III), antimony(III) and -bismuth(II)

Abstract The crystal structures of the title compounds, M(S2COiC3H7)3, M = As(III), (1); Sb(III), (2); and Bi(III), (3) have been determined by three dimensional X-ray diffraction techniques and refined by a least square method. Crystals of (1) and (2) are isomorphous and both crystallize in the rhombohedral space group R 3 , with unit cell parameters for (1) ahex = 11.559(2), chex = 28.131(3) A and for (2) ahex = 11.696(2) and chex = 28.135(2) A, Z = 6. The central metal atom in both (1) and (2) is coordinated by three asymmetrically chelating xanthate ligands [AsS 2.305(2) and 2.978(2) A and SbS 2.508(1) and 3.006(1) A] which form a distorted octahedral environment consistent with the presence of a stereochemically active lone pair of electrons. Crystals of (3) are orthorhombic, space group Pnma, Z = 4 with dimensions a = 11.003(3), b = 20.833(4) and c = 9.428(2) A. The environment of the bismuth atom in (3) is seven coordinate and is comprised of six sulphur atoms, derived from three asymmetrically coordinating xanthate ligands, and a bridging sulphur atom from a neighbouring molecule which results in the formation a polymeric array. For (1) final R and RW 0.050 and 0.047 respectively for 936 reflections [I ⩾ 3σ(I); (2) R 0.040, Rw 0.040 for 1455 reflections I ⩾ 2σ(I)]; and (3) R 0.052, Rw 0.039 for 1796 reflections [I ⩾ 2σ(I).

Reversible and non-reversible inclusion compounds of the nickel xanthate adducts with 4,4'-bipyridyl and with 2,2'-dipyridylamine

Abstract The crystal structures of the benzene inclusion compound of the 2,2′dipyridylamine nickel ethylxanthate adduct, [Ni(S2COEt)2(2,2′-dpa)·C6H6], and the carbon tetrachloride inclusion compound of the 4,4′-bipyridyl nickel butylxanthate adduct, [Ni(S2COBu)2(4,4′-bipy)·2CCl4]n, have been determined by single crystal X-ray diffraction methods. Crystals of [Ni(S2COEt)2(2,2′-dpa)·C6H6] are triclinic, space group P 1 , a = 8.755(2), b = 12.680(3), c = 13.012(3) A, and α = 110.12(2), β = 106.09(2), γ = 92.56(2)° with Z = 2; R and Rw were 0.060 and 0.064 respectively for 3073 unique observed reflections. The nickel atom is in an octahedral environment, surrounded by two chelating xanthate ligands and one chelating 2,2′-dpa molecule. The benzene molecules sit in cavities formed by the packing of the [Ni(S2-COEt)2(2,2′-dpa)] molecules, there being two benzene molecules in each cavity. Crystals of [Ni(S2COBu)2(4,4′-bipy)·2CCl4]n are triclinic, space group P 1 , a = 6.6349(8), b = 11.3135(9), c = 13.1101(9) A, α 64.454(7), β = 79.551(8), γ = 84.984(8)°, Z = 2; R and Rw were 0.040 and 0.044 respectively for 3018 unique reflections. The nickel atom is in an octahedral environment which results from two chelating xanthate ligands and two nitrogen atoms, one from each of two, 4,4′-bipyridyl ligands. The nitrogen atoms are in a trans configuration which gives rise to a linear polymer of composition [Ni(S2COBu)2(4,4-bipy)]n. The CCl4 molecules sit in open channels, parallel to the a-axis, which are formed by the packing of the linear polymeric chains of the complex.

Crystal structures of Ph2Te(S2P(OEt)2)2 and of two modifications of Ph2Te(S2CNEt2)2

Abstract Crystals of Ph 2 Te[S 2 CNEt 2 ] 2 are monclinic; one modification has space group P 2 1 , a 8.3349(9), b 8.389(1), c 18.106(2) A, β 92.51(1)°, Z = 2. The second modification of Ph 2 Te[S 2 CNEt 2 ] 2 has space group C 2/ c , a 16.552(2), b 14.363(3), c 12.184(2) A, β 121.61(1)°, Z = 4. Crystals of Ph 2 Te[S 2 (OEt) 2 ] 2 ( 3 ) are orthorhombic, space group P 2 1 2 1 2 1 , a 8.297(1), b 16.311(3), c 21.117(3) A. All three structures are monomeric and contain a stereochemically active lone pair at the tellurium atom, making the Te effectively seven coordinate in each case.