Linear chain structures

The TCNQ molecule in [TR(bzim)]2-TCNQ is sandwiched between two units of [ J,-N, C -bzimAu]3 in a face-to-face manner so that it is best represented by the formula (7t-[ J,-N, C -bzimAu]3)( j,-TCNQ)(7t-[p-N, C -bzimAu]3). The cyanide groups clearly are not coordinated to the gold atoms. The distance between the centroid of TCNQ to the centroid of the AU3 unit is 3.964 A. The packing of [TR(bzim)]2-TCNQ shows a stacked linear-chain structure with a repeat pattern of-(Au3)(Au3)(p-TCNQ) (Au3)(Au3)(p-TCNQ)- an ABBABB repeat The complex [TR(bzim)]2-TCNQ contains two very short intermolecular Au Au distances of 3.152 A (identical for the two aurophilic bonds). The intermolecular Au Au distance is even shorter than the intramolecular distances in the starting compound, which are 3.475, 3.471, and 3.534 A. The adjacent AU3 units in [TR(bzim)]2-TCNQ form a chair-type structure rather than the face-to-face (nearly eclipsed) pattern reported in Balch s studies of the nitro-9-fluorenones adducts with the trinuclear Au(I) alkyl-substituted carbeniate complexes. 

Macromolecules differ from small molecules in a number of critical properties. First, the linear chain structure confers elasticity, toughness, and strength on the solid state system. This is a consequence of the reorientational freedom of the skeletal bonds and of their ability to absorb impact or undergo elastic deformation by means of conformational changes rather than bond cleavage. 

Halide bridged nickel(II)/platinum(IV) and palladium(II)/platinum(IV) complexes with onedimensional linear-chain structures have been studied extensively.556-559 These are analogous to the linear-chain platinum(II)/platinum(IV) systems described in Section 6.5.13 and have similar broad and intense intervalence bands.556-559 However, they have weaker metal-metal interactions resulting in more localized valences than the all platinum analogues.556-559... 

Coordination studies of acyclic thioether ligands to silver(I) centers has also been studied. Poly(alkylthio)aromatic systems have been used to form supramolecular silver(I) compounds. With the ligand 2,3,5,6-tetrakis(isopropylthio)benzoquinone the compound has a linear chain structure in which silver(I) has a tetrahedral coordination.1156 A similar structure has the compound with the hexakis(methylthio)benzene,1157 but with the hexakis(tolylthio)benzene the silver... 

Both compounds crystallise in the trigonal space group P 3cl, and this space group remains unchanged upon the Fe(II) spin crossover. The structure of [Fe(btzp)3](Cl04)2 [87] has been solved at 200 K and 100 K, whereas the structure of [Fe(btze)3](BF4)2 [88] has been determined at 296, 200, 150 and 100 K. A projection of the linear chain structure of [Fe(btzp)3](Cl04)2 [87] is displayed in Fig. 17. 

Fig. 1 Schematic drawing to show the concept of system dimensionality (a) bulk semiconductors, 3D (b) thin film, layer structure, quantum well, 2D (c) linear chain structure, quantum wire, ID (d) cluster, colloid, nanocrystal, quantum dot, OD. In the bottom, it is shown the corresponding density of states [A( )] versus energy (E) diagram (for ideal cases).

Fig. 4.37 (a) On the Ir (001) surface, for an island of fewer than 6 Ir atoms, a two-dimensional structure is mctastable, whereas the linear chain structure is stable. (/) An island of 6 Ir atoms equilibrated at 460 K ( 7) one atom is field evaporated from the 6-atom island (Hi) upon heating to 450 K, the two-dimensional five-atom island reconfigures to a linear chain, (b) For an island of 6 or more Ir atoms, the linear chair is mctastable whereas the two-dimensional island is stable. (/) 6 Ir atoms in a linear chain, equilibrated at 315 K (if) upon heating to 450 K, the island transforms into a two-dimensional structure. From Schwoebcl ... 

Co(N03)2 6H20 are treated with a large excess of sodium 5-phenyl tetrazolate are thought to contain a polymeric complex [Co(5-Ph-tta)2(H20)2] with a molecular weight in the region 104 to 105. A rigid linear chain structure with double tetrazolate bridges is proposed (177). 

Stacking in all of these complexes is the result of additional intermolecular aurophilic interactions between four of the six Au1 atoms in adjacent units giving rise to stacked linear-chain structures with a -BBABBA- pattern. The intermolecular Au1- -Au1 distances, between 3.0658(7) and 3.3298(5) A, are usually similar or slightly shorter (in the case of the mercury derivative) than the intramolecular ones, with average distances between 3.08 and 3.493 A (see Table XXI). Only in the case of the TCNQ derivative the intermolecular aurophilic contacts (3.152 A) are clearly shorter than the intramolecular ones (3.457, 3.471 and 3.534 A), which could be ascribed to charge-transfer from the electron-rich gold center to the electron acceptor TCNQ. 

Fig. 32 Packing diagram showing the linear chain structure of [(TPA)2AuI] [AuI(CN)2]> (TPA is l,3,5-triaza-7-phosphaadamantane). For clarity, only phosphorus atoms in the TPA ligand are shown. From [54]...

A single crystal X-ray crystal structure analysis established a linear chain structure with both tin and silicon having tetrahedral configuration. In contrast to the polymeric structure found in the solid state, the stannasiloxane 67 forms a six-membered ring in... 

Dan. M, Udayakumar. D, Rao, C. N, R, Transformation of a 4-membered Ring Zinc Phosphate SBU to a Sodalite-Related 3-Dimensional Structure through a Linear Chain Structure. Chem. Commun. 2003. 2212-2213. 

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