Don Craig

Syntheses and X-ray structures of molecular metal polyselenide complexes [M(Se4)2]2− M = Zn, Cd, Hg, Ni, Pb

Abstract Bis-tetraselenide complexes [M(Se4)2]2− M = Zn (1), Cd (2), Hg (3), Ni (4) and Pb (5) are readily prepared by the reaction of Se, Na and MCl2 in DMF, and crystallized with Ph4P+. Crystal structure determinations reveal pseudo-tetrahedral coordination in 1, 2 and 3, slightly distorted square-planar coordination in 4, and in 5 a four coordinate stereochemistry interpreted as primary trigonal orthogonal, plus one secondary bond. There is no evidence of variable size in the metallapolyselenane chelate rings, in contrast with data for comparable polysulphide complexes.

Syntheses and structures of molecular copper and silver polyselenide complexes [M4(Se4)x(Se5)3−inx]2−

Abstract The first copper and silver polyselenide complexes, (Ph4P)2[Cu4(Se4)2.4(Se5)0.6] (1) and (Ph4P)2[Ag4(Se4)2.1(Se5)0.9] (2) are formed by reaction of Se, Na, CuCl2 or AgNO3, and Ph4PBr in DMF. Crystal structure determinations reveal molecular clusters, with M4 tetrahedra edge-bridged as M4(Sex)3 by the terminal Se atoms of three chelating polyselenide ligands. The coordination at each M atom is approximately trigonal planar. Some of the polyselenide ligands are disordered in chain length and in conformation of the metallapolyselenane rings.

[S4M10(SPh)16]4–(MZn, Cd), a molecular fragment of the sphalerite ms lattice: structural congruence of metal sulphides and metal thiolates

Treatment of [S4(SPh)10]2–(M = Zn, Cd) with sulphur yields [S4M10(SPh)16]4– with a molecular structure tetrahedro-(µ3-S)4-octahedro-M6-truncated tetrahedro-(µ-SPh)12-tetrahedro-(MSPh)4, in which the M10S20 array is congruent with a fragment of the sphalerite lattice.

Syntheses and structures of anionic metal polyselenide complexes [(C5H5)Mo(Se4)2]− and [Sn(Se4)3]2−, crystallized with Ph4P+

Abstract Reaction of (η5-C5H5)2Mo2(CO)6 with selenium and sodium in DMF yields [(η5-C5H5)Mo(Se4)2]− (1), which was crystallized with Ph4P+ and characterized by crystal structure determination. With two chelating tetraselenide ligands, 1 is the first member of a new class of mono(cyclopentadienyl)-bis(polychalcogenide) metallates, distinct from existing compounds which are formulated [(η5-C5R5)2M(Ex)] (E = S, Se; x = 3, 4, 5). (Ph4P)2[Sn(Se4)3] (2), from reaction of selenium, sodium, SnCl2 and Ph4PBr in DMF, shows no evidence in its crystal structure of the disordered ring size and conformation found in polysulphide homologues.

The first endoannular metal halide–cucurbituril: cis-SnCl4(OH2)2@cucurbit[7]uril

We describe the insertion and physical entrapment of cis-SnCl4(OH2)2 completely inside the annulus of the cyclic methylene-linked glycoluril heptamer known as cucurbit[7]uril (Q7). This is the first endoannular metal halide–cucurbituril complex, [cis-SnCl4(OH2)2]@Q7, contained in crystalline {[cis-SnCl4(OH2)2]@Q7}2·(H3O+)6[SnCl62−]3(H2O)23. The crystals are formed by reaction of Q7 and SnCl4 in hydrochloric acid. The cis-SnCl4(OH2)2 complex is contained completely within Q7, and is stabilised by the formation of excellent internal hydrogen bonds between coordinated nwater and carbonyl oxygen. The two crystallographically independent Q7 molecules in the crystal are incompletely occupied (75%, 50%), probably due to the premature crystallisation of the insoluble crystals. The crystal packing is analysed in some detail in order to understand the low solubility and to enable formation of more soluble forms of [cis-SnCl4(OH2)2]@Q7 which will allow development of its new coordination chemistry. Some results of computational modelling of the dynamics of ingress of the chlorotin complexes into Q7 are reported.

The crystallisation of polyoxo-molybdate and -tungstate anions with phenylated phosphonium and arsonium cations, in relation to the crystal packing and species in solution

Polyoxometallate anions often occur as mixtures of species in solution. We have investigated the possible selectivity of crystallisation of these anions using arylated cations that commonly adopt cation dominated crystal packing motifs known as multiple aryl embraces. The crystallisation and crystal structures of the compounds (Ph4P)2[Mo2O7], (Ph4P)2[Mo6O19](CH3CN)2, (Ph4P)2[W6O19](DMSO)2, (MePh3As)2[Mo6O19], (Ph4P)2(Na)2[Mo8O26](CH3CN)2(H2O), (Bu4P)3(NH4)[Mo8O26], (Ph4P)4[W10O32] and (MePh3P)4[W10O32] are described, and solution compositions measured by electrospray mass spectrometry. The crystal packing of these and some related literature compounds is analysed and interpreted. One- and two-dimensional nets of embracing Ph4P+ cations are general, with segregated cations and segregated anions, and it appears that Ph4P+ cation arrays control the separations of anions, with solvent occupying any gaps between anions. An embracing pair of MePh3As+ is cube-shaped, as is [Mo6O19]2−, and together they form a pseudo face-centered cubic array. In (MePh3P)4[W10O32] this fcc array is expanded by additional stuffed cations. The electrostatic energies of the ion arrays are discussed, in the context of the segregation of homo-charged ions, and the commensurabilities of the ion arrays. Using electrospray mass spectrometry of the solutions from which the crystals formed, we show that (Ph4P)2[Mo2O7] crystallises from a solution containing [Mo8O26]4−.

Reactions of [MCl2(ppqMe2)2] (M=Pd, Pt) with I− and with CF3SO3H/I− including the synthesis and X-ray crystal structure of the palladium phosphidoxo complex [Pd2(μ-I)2{(PPh20)2H}2]

Abstract The compounds [MI 2 (ppqMe 2 ) 2 ] (5: Mue5f8Pd; 6: Mue5f8Pt) have been synthesised and their thermolyses and reactions with strong acids investigated. Thermolysis of 5 in the presence of excess iodide ion caused complete decomposition of the complex whereas the corresponding reaction of 6 gave the P∼O chelated complex [Pt(ppqMe) 2 ] ( 7 ) in good yield. Treatment of 5 with CF 3 SO 3 H/I− facilitated the loss of the 2,5-dimethoxyphenyl substituent from each phosphine ligand and gave the iodo-bridged palladium(II) phosphidoxo complex [Pd 2 (μ-I) 2 {(PPh 2 O) 2 H} 2 ] ( 8 ). An X-ray single crystal structural analysis of 8 is reported.

Molecular structure of tetrakis[benzenethiolatotrimethylplatinum(IV)], (μ3-SPh)4(PtMe3)4

Abstract The crystal structure of the title compound is reported, and the geometry and symmetry of the three-fold bridging by the arylthiolate ligand with two-fold symmetry is assessed. Pt S bond lengths are differentiated by only 0.04A. Crystal data: C36H56Pt4S4, M = 1897.4, tetragonal, space group P43212, a = 14.187(1), c = 40.399(6)A, U = 8131.11A3, Z = 8.

Tetrahedral HgS4 and linear HgS2 coordination in the crystal structure of Na2Hg3S4(H2O)2

Abstract The colourless crystalline compound Na2Hg3S4(H2O)2 obtained from the heterogeneous reaction of HgS and Na2S in DMF containing residual water, contains mercury sulphide chains {[Hg2S3]2−}∞ in which tetrahedral HgS4 units [D2 site symmetry, Hgue5f8S = 2.558(2) A] are linked along the chain by pairs of digonal mercury atoms [C2 site symmetry, Hgue5f8S = 2.362(2) A, Sue5f8Hgue5f8S = 166.2(1)°]. These chains are separated by {[Na2(OH2)2]2+}∞ chains, and connected to them by Oue5f8Hue5f8S hydrogen bonds [3.261(7) A] and Naue5f8S contacts [2.946(5), 2.974(5) A]. The structure embodies and mimics the coordination in both of the HgS minerals, cinnabar and metacinnabar.

The preparation and crystal structure of an anionic silver pentasulphide chain in ∞[Ag(S5)−](Me4N+)

Abstract Reaction of Ag + with (Bu 4 N) 2 S 6 in acetonitrile, in the presence of Me 4 NCl, yields the orange compound ∞[Ag(S 5 ) − ](Me 4 N + ) ( 1 ). Unlike all other silver polysulphide complexes, 1 is non-molecular in one-dimension, with propagation by a glide plane. Each silver atom is tetrahedrally coordinated by sulphur atoms from three different (S 5 ) 2− ions, and each (S 5 ) 2− ion makes four connections to three different silver ions, including an AgS 4 chelate ring involving a non-terminal sulphur atom. The structure is different in detail from that of NH 4 CuS 4 . Crystal data: space group Cc , a = 10.860(10), b = 18.313(7), c = 9.177(9) A, β = 139.77(3)°, V = 1179(2) A 3 . D calc = 1.93 g cm −3 ( Z = 4). 963 independent observed [ I /σ( I ) > 3] reflections (Mo- K α ), R = 0.044, R w = 0.052.