Göran Helgesson

On the coordination number of the metal in crystalline halogenocuprates(I) and halogenoargentates(I)

Publisher Summary This chapter presents a summary on the various structural motifs documented for halogenocuprate(I) and halogenoargentate(I) ions in the solid state, placing special emphasis on the variations in the coordination number of the metal. Anionic configurations in crystalline halogenocuprates(I) and halogenoargentates(I) appear to be strongly dependent on the nature of the cation, thus permitting, in principle, the preparation of a species, containing copper(1) or silver(I), with a desired coordination number by pertinent choice of cation. The interpretation and correlation of spectroscopic properties, in the context of structure and bonding, for compounds of group IB and group IIB metals, have been discussed in the chapter. Solid-state structures documented hitherto for halogenocuprate(I) and halogenoargentate(I) ions are described in the order of increasing coordination number of the metal. Possible correlations between the coordination number of copper(I) or silver(I) in the anion and properties of the cation with which it is coprecipitated, such as size, shape, and exposure of the positive charge, are also discussed. The most widespread method of preparation is reaction between the metal(I) halide and the halide salt of the appropriate cation dissolved in an organic solvent.

A novel tetranuclear iodoargentate(I) ion, [Ag4I8]4-, with a cubane-type core

Abstract A novel tetranuclear iodoargentate(I) anion, [Ag4I8]4−, with a cubane-type Ag4I4 core has been isolated as the tetrapropylammonium salt and characterised by means of crystal structure determination. There are two crystallographically independent anions, each of which is situated around a two-fold axis. One of the terminal iodide ligands in one such [Ag4I8]4− anion is disordered, as are two of the tetrapropylammonium cations. The ordered terminal AgI bonds range from 2.748(2) to 2.765(2) A and the bridging AgI from 2.897(2) to 2.932(3) A, all four silver(I) centres exhibiting distorted tetrahedral coordination geometry. The compound crystallises in the monoclinic space group C2, with a=26.836(6), b=12.535(4), c=24.509(6) A, β=118.54(2)°, V=7243(4) A3, at −120 °C, and Z=4. Full-matrix least-squares refinement yielded a final R=0.042 (Rw=0.045) for 333 parameters and 3784 observed reflections.

Preparation and characterisation of tetraphenylphosphonium and tetraphenylarsonium halogenoargentates(I), including a new lodoargentate(I) cluster, [Ag4I8]4–, containing three- and four-co-ordinated silver(I)

A new iodoargentate(I) cluster [Ag4I8]4–, containing three- and four-co-ordinated silver(I) has been isolated with the tetraphenylphosphonium and tetraphenylarsonium cations and characterised by means of crystal structure determination. Tetrakis(tetraphenylphosphonium) and tetrakis(tetraphenylarsonium) hexa-µ-iodo-di-iodotetra-argentate(I)[(1) and (2)] are isostructural and crystallise in the triclinic space group P, with a= 13.453(7), b= 16.607(9), c= 11.068(7)A, α= 102.83(4), β= 103.94(4), γ= 82.96(4)°, Z= 1, and a= 13.446(3), b= 16.712(3), c= 11.293(4)A, α= 103.36(2), β= 103.84(2), γ= 83.43(2)°, Z= 1, respectively. The initial phases crystallising from solution during formation of [PPh4]4[Ag4I8] and [AsPh4]4[Ag4I8] are [PPh4][Ag3I4](3) and [AsPh4][Ag3I4](4), respectively. The latter compounds are also isostructural with one another and crystallise in the monoclinic space group P21/c with Z= 4 and a= 13.380(5), b= 26.536(5), c= 8.504(4)A, β= 108.09(4)° for (3), and a= 13.448(7), b= 26.723(4), c= 8.546(4), β= 107.99(4)° for (4). With tetraphenylarsonium as cation, discrete chloroargentate(I) and bromoargentate(I) anions, [Ag2X4]2–, X = Cl (5) or Br (6), containing distorted trigonal-planar co-ordinated silver(I), have been obtained. Bis(tetraphenylarsonium)di-µ-chloro-dichlorodiargentate(I)(5) and bis(tetraphenylarsonium) di-µ-bromo-dibromodiargentate(I)(6) both crystallise in the monoclinic space group P21/n with Z= 2 and a= 14.280(6), b= 8.200(4), c= 19.118(8)A, β= 101.19(3)°, and a= 14.546(4), b= 8.072(2), c= 19.854(5)A, β= 102.73(2)°, respectively. The tetranuclear [Ag4I8]4– anion is centrosymmetric and can be described in terms of two edge-sharing silver(I)–iodide tetrahedra, each linked via a common edge to an approximately planar silver(I)–iodide triangle. In the latter the silver(I) atom is displaced 0.054(1)(1) and 0.026(1)A(2) from the plane through the three iodide ligands. The Ag–I distances associated with the three-co-ordinated centre are 2.727(2), 2.763(2), and 2.765(2)A(1), and 2.721 (1), 2.757(1), and 2.766(1)A(2), while those involving the four-co-ordinated centre range from 2.842(2) to 2.991 (2)(1) and 2.846(1) to 2.973(1)A(2). The Ag ⋯ Ag separations are 3.171 (2) and 3.256(2), and 3.198(1) and 3.306(2)A in (1) and (2), respectively. The [Ag3I4]– polymers in [PPh4][Ag3I4](3) and [PPh4][Ag3I4](4) consist of triple chains of edge-sharing Ag–I tetrahedra, Ag–I distances ranging from 2.796(2)–2.972(3)(3) and 2.798(4)–2.966(4)A(4). The anions in [AsPh4]2[Ag2Cl4] and [AsPh4]2[Ag2Br4] are centrosymmetric, approximately planar entities in which silver(I) is displaced 0.004(1)(5) and 0.048(1)A(6) from the ligand plane, and the Ag ⋯ Ag separations are 3.659(2)(5) and 3.549(2)A(6). In [Ag2Cl4]2–, the bridging Ag–Cl distances differ considerably from one another, i.e. 2.446(2) and 2.809(2)A, the terminal Ag–Cl bond being 2.359(2)A. In [Ag2Br4]2–, there is less discrepancy between bridging distances: 2.614(1) and 2.741 (1)A; Ag–Br(terminal) is 2.481 (1)A.

Two compounds containing dinuclear three-co-ordinated halogenoargentate(I) anions: crystal structures of bis(tetraphenylphosphonium) di-µ-chlorodichlorodiargentate(I) and bis(tetraphenylphosphonium) di-µ-bromodibromodiargentate(I)

Two new dinuclear halogenoargentate(I) anions, [Ag2Cl4]2– and [Ag2Br4]2–, containing distorted trigonal-planar co-ordinated silver(I), have been characterised by means of crystal structure determination. Bis(tetraphenylphosphonium) di-µ-chloro-dichlorodiargentate(I) and bis(tetraphenylphosphonium) di-µ-bromo-dibromodiargentate(I) both crystallize in the monoclinic space group P21/n with Z= 2 and a= 14.190(9), b= 8.062(3), c= 19.177(10)A, β= 101.64(4)°, and a= 14.525(9), b= 7.914(3), c= 20.010(10)A, β= 103.16(5)°, respectively. Both anions are centrosymmetric and planar or approximately planar, silver(I) being displaced 0.0014(8) and 0.0587(6)A from the ligand plane in [Ag2Cl4]2– and [Ag2Br4]2–, respectively. In [Ag2Cl4]2– the bridging Ag–Cl distances differ considerably from one another, i.e. 2.447(1) and 2.792(2)A, the terminal Ag–Cl bond being 2.358(2)A. In [Ag2Br4]2– there is less discrepancy between bridging distances: 2.617(1) and 2.752(2)A; Ag–Br(terminal) is 2.491(1)A.

Mononuclear trigonal planar trichloroargentate(I) and tribromoargentate(I) ions isolated as their dibenzo-18-crown-6 potassium and rubidium salts

Mononuclear trichloroargentate(I) and tribromoargentate(I) ions have been isolated with dibenzo-18-crown-6 potassium and rubidium cations and characterised by means of crystal structure determination. The four compounds prepared [ML]3[AgX3]X [L = dibenzo-18-crown-6 (6,7,9,10,17,18,20,21-octahydrodibenzo[b,k][1,4,7,10,13,16]hexaoxacyclooctadecine); X = Cl, M = K 1 or Rb 2; X = Br, MK 3 or Rb 4], crystallise in the hexagonal space group P63/m, with Z= 2, 1 and 3, and 2 and 4 being isostructural, respectively [1, a= 14.012(2) and c= 18.958(2)A; 2, a= 13.786(2) and c= 19.507(2)A; 3, a= 14.154(2) and c= 19.045(4)A; and 4, a= 14.000(1) and c= 19.591(3)A]. The anions exhibit perfect D3h symmetry with Ag–Cl 2.463(2)A in 1, 2.447(2)A in 2 and Ag–Br 2.561(2)A in 3, 2.550(1)A in 4. In compounds 2 and 4, the rubidium ions appear to be somewhat too large for the crown cavity and are displaced towards the anion, such that each Rb+ is involved in two short Rb+⋯ X contacts [3.272(2) and 3.487(2)A in 2, 3.420(2) and 3.597(2)A in 4]. In the potassium compounds, 1 and 3, however, K+ is accommodated in the cavity of the crown and the cations are rotated relative to the anions so that there is only one short K+⋯ X contact per potassium ion [3.019(3)A in 1 and 3.199(5)A in 3]. The stronger outer-sphere co-ordination in the potassium compounds thus results in a slight lengthening of the Ag–X bond.

Structure of diphenyltriazole, a potential monomer for a conductive polymer

Abstract The chemical structure of 3,5-diphenyltriazoles indicates that these compounds may have the potential to be monomers for conjugated polymers. Monomeric 4-ethyl-3,5-diphenyl-1,2,4-4H-triazole has been synthetized according to established procedures and single crystals of the compound grown. From X-ray structure determination we find a monoclinic space group Cc, with a = 5.616(4), b = 17.511(4), c = 13.778(3) A , β = 96.30(3)° and Z = 4 . The structure is polar in the ac-plane. The phenyl groups are twisted approximately 90° relative to each other and the molecules are packed in an alternating chain pattern.

Structure of 3,4-diphenyl-1,2,4-triazoles, possible bases for new conductive polymers

Crystal and molecular structures of two new 3,4-diphenyl-1,2,4-triazoles show that an appreciable degree of electron delocalization is present in the combined two phenyl-triazole ring systems. Phenyl-ring twisting relative to the triazole rings is provoked by steric effects of side groups of the triazole rings.