Preparation and X-ray analysis of 1-methyl-1,3,5,7-tetraazaadamantan-1-ium triiodide [(CH2)6N4CH3]I3

Preparation, photoluminescence and excited state properties of the homoleptic cluster cation [(W6I8)(CH3CN)6]4

Solvated tungsten iodide cluster compounds are presented with the homoleptic cluster cation [(W₆I₈)(CH₃CN)₆]⁴⁺ and the heteroleptic [(W₆I₈)I(CH₃CN)₅]³⁺, synthesized from W₆I₂₂ in acetonitrile. Crystal structures were solved and refined on deep red single-crystals of [(W₆I₈)(CH₃CN)₆](I₃)(BF₄)₃·H₂O, [(W₆I₈)I(CH₃CN)₅](I₃)₂(BF₄), and on a yellow single-crystal of [W₆I₈(CH₃CN)₆](BF₄)₄·2(CH₃CN) on the basis of X-ray diffraction data. The structure of the homoleptic [(W₆I₈)(CH₃CN)₆]⁴⁺ cluster is based on the octahedral [W₆I₈]⁴⁺ tungsten iodide cluster core, coordinated by six apical acetonitrile ligands. The electron localisation function of [(W₆I₈)(CH₃CN)₆]⁴⁺ is calculated and solid-state photoluminescence and its temperature depedence are reported. Additionally, photoluminescence and transient absorption measurements in acetonitrile are shown. Results of the obtained data are compared to compounds containing [(M₆I₈)I₆]^2- and [(M₆I₈)L₆]^2- (M = Mo or W; L = ligand) clusters.

Polyhalide anions in crystals. Part 2. I3−asymmetry and N—H … I bonding: triiodides of the Me2NH2+, Ph2I+, tropanium,N,N,N′,N′-Me4-1,2-ethanediammonium,N,N,N′,N′-Me4-1,3-propanediammonium,N-Me-piperazinium(2+), andN,N′-Me2-piperazinium(2+) cations, and Me2NH2I

Crystal-structure determinations are reported for Me2NH2I3, (Ph2I)I3, tropanium-I3, [Me2HN(CH2)2NHMe2](I3)2, [Me2HN(CH2)3NHMe2](I3)2, (N-Me2-piperazinium) (I3)2•H2O, (N,N′-Me2-piperazinium)(I3)2, and Me2NH2I. The features of these and relevant literature structures are used to (1) classify triiodide structures by their ion-packing types; (2) analyze the relationship between the two I—I bond lengths d and d* in the I3−anion; and (3) examine the effect of N—H(N)… I hydrogen bonding on the symmetry of the I3−anion. It is found that the d,d* relationship can be represented to a high degree of correlation by the power function d* − d0 = K(d − d0)−c(d* ≥ d,d0 = d(I—I) in I2(g)) based on the 3c4e model of the anion. An empirical correlation is shown to exist between the H(N)… I and N … I distances both for unbranched and branched N—H(N)… I bonds. Comparison of the degree of asymmetry of I3−in two samples, one containing H-bonded I3−anions, the other with H-bonding absent, leads to the conclusion that while H-bonding is a factor affecting I3−symmetry, it is not a preferential factor. The four 1:2 title triiodides have structures of, or related to, the CdI2type, in which the anions form infinite pseudo-hexagonal channels. The positioning of the divalent cations on the axes of these channels gives rise to an interesting "vernier" effect governed by the cation length and H-bonding ability. Bonding in centrosymmetric I4rings in (Ph2I)I3and (Ph2I)I is examined. Key words: crystal structures, hydrogen bond, iodine–iodine bonds, polyhalide anions, triiodides.

Polyhalide anions in crystals. Part 1. Triiodides of the Me4N+, Me4P+, quinuclidinium, 1-azoniapropellane, and 1,4-diazoniabicyclo[2.2.2]octane (DabcoH22+) cations, and 1,10-phenanthrolinium(1+) tribromide

Crystal-structure determinations are reported for Me4NI3(4MI3, Pnnm, a = 10.107(2), b = 14.141(2), c = 8.252(5) Å, Z = 2), quinuclidinium I3(QI3, Pnnm, a = 10.290(2), b = 14.011(2), c = 8.813(2) Å,Z = 2), Me4PI3(4MPI3,P42/m, a = 15.098(4), c = 13.770(4) Å, Z = 10), 1-azoniapropellane I3(API3, P21/c, a = 15.131(7), b = 28.453(6), c = 22.848(8) Å, β = 108.53(3)°, Z = 24), 1,4-diazoniabicyclo[2.2.2]octane (I3)2(Da2I3, P21/m, a = 9.671(6), b = 8.127(2), c = 11.144(3) Å, β = 96.60(3)°, Z = 2), and 1,10-phenanthrolinium(1+) Br3(phenBr3, [Formula: see text] a = 8.370(2), b = 10.410(4), c = 8.171(2) Å, α = 107.52(2)°, β = 97.35(1)°, γ = 94.84(2)°, Z = 2). The nearly isostructural 4MI3 and QI3 are of a distorted anti-NiAs type. The 4MPI3 and API3 structures can be regarded as consisting of distorted CsCl-type coordination cuboids; both are unexpectedly complex, 4MPI3 (not isostructural with 4MI3) containing cations of two and anions of three types, API3 containing cations of six and anions of seven types. API3 thus represents an extreme case of a frustrated CsCl structure. The ion packing in Da2I3 is related to that in CaF2. The distortion of one of the two nonequivalent I3−anions in Da2I3 is one of the largest, if not the largest on record (I—I = 2.793(2) and 3.167(2) Å, I-I-I = 172.47(4)°), and attributable to the involvement of the anion in a strong N—H … I bond, H … I = 2.78 Å. The bifurcated H-bond in which the protonated cation nitrogen in phenBr3is engaged has an intra-cation, N—H(N)… N, branch and an inter-ion branch, N—H(N)… Br. Key words: crystal structure, hydrogen bond, polyhalide anions, tribromides, triiodides.