Thallophilic interactions in aryloxide compounds: the [Tl2(mu2-OAr)4] structural motif in (TlOAr)4 and Tl2Cu(OAr)4 compounds

Two thallium aryloxide compounds TlOC6F5 (TlOAr(F)) and bis-3,5-TlOC6H3(CF3)2 (TlOAr') have been recrystallized from THF and crystallographically characterized in different isomeric forms. The latter compound forms a solvated tetrameric cubane, [TlOAr']4.THF, 1. The TlOAr(F) compound crystallized with a similar stoichiometry, [TlOAr(F)]4.2 THF, 2, but contains a [Tl2(mu2-OAr(F))4] unit that includes a thallophilic interaction at a distance of 3.5943(15) angstroms. Solution 205Tl and 203Tl NMR studies of 1 and 2 support the retention of a cubane structure for 1 in solution and suggest a similar structure for 2 with coupled thallium centers down to -90 degrees C. Fluorescence spectroscopy data for both compounds 1 and 2 in THF are consistent with LMCT. DFT calculations of 1, 2, and three models of the [Tl2(mu2-OAr(F))4] unit show a bonding overlap of the bridged thallium atoms in 2 and are also used to describe the bonding in 1. The structures of two heterobimetallic compounds, Tl2Cu(OAr(F))4, 4, and Tl2Cu(OAr')4, 5, with the [Tl2(mu2-OAr(F))4] structural motif and thallophilic contacts of 3.86(6) and 3.564(1) angstroms, respectively, are described. The crystal structures of the unsolvated of TlOAr(F), 2b, solvated heterobimetallic derivative Tl2Cu(OAr')4.2THF, 5b, and the monomeric (18-crown-6)TlOAr(F), 3, and 205Tl NMR spectra of TlOC6H5, 6, are also reported for comparison purposes.     

The New Homoleptic Tetracyanamidoaluminate LiBa2[Al(CN2)4]

The new tetracyanamidoaluminate LiBa₂[Al(CN₂)₄] was prepared by solid state metathesis reaction in a fused copper ampoule from a mixture of BaF₂, AlF₃, and Li₂(CN₂) at 550 °C. The crystal structure was solved and refined based on single‐crystal X‐ray diffraction data [P2₁2₁2₁, Z = 4, a = 6.843(1) Å, b = 11.828(2) Å, c = 11.857(2) Å]. The compound belongs to the known formula type LiM₂[Al(CN₂)₄] (M = Sr, Eu) containing the homoleptic [Al(CN₂)₄]^5– ion. However, LiBa₂[Al(CN₂)₄] forms a distinct crystal structure, containing a two‐dimensional [(NCN)_2/2Li(NCN)₂Al(NCN)_2/2] network with four‐coordinate Li⁺ and Al³⁺ ions. Two crystallographically independent Ba²⁺ ions are situated in eightfold environment of terminal nitrogen atoms of cyanamide ions.     

1-D and 2-D homoleptic dicyanamide structures, [Ph4P]2[CoII[N(CN)2]4] and [Ph4P][M[N(CN)2]3] (M = Mn, Co)

The homoleptic complexes [Ph(4)P](2)[Co[N(CN)(2)](4)] and [Ph(4)P][M[N(CN)(2)](3)] [M = Co, Mn] have been structurally as well as magnetically characterized. The complexes containing [M[N(CN)(2)](4)](2-) form 1-D chains, which are bridged via a common dicyanamide ligand in [M[N(CN)(2)](3)](-) to form a 2-D structure. The five-atom [NCNCN](-) bridging ligands lead to weak magnetic coupling along a chain. The six [NCNCN](-) ligands lead to a (4)T(1g) ground state for Co(II) which has an unquenched spin-orbit coupling that is reflected in the magnetic properties. Long-range magnetic ordering was not observed in any of these materials.     

Configurations of the [Pd(NO2)4]2- Complex Anion: Crystal Structure of Ag4A2[M(NO2)4]3 (M = Pd, Pt; A = K, Rb)

An integrated Xray diffraction study was performed on polycrystals and single crystals of three new isostructural phases with general formula Ag₄A₂[M(NO₂)₄]₃ (M = Pd, Pt; A = K, Rb). Data on the crystal structure solution (CAD4 diffractometer, MoK radiation, graphite monochromator = 2–30° are presented. In one crystallographically independent [M(NO₂)₄]^2- complex anion, the planar square coordination of the central atom is completed to 4 + 2 by two oxygen atoms at a distance of 3.02–3.12 in the other anion, it is completed to 4 + 1 + 1 by an oxygen atom at a distance of 3.12–3.30 and an Ag⁺ cation at a distance of 3.04–3.11 . Part of the Ag⁺ cations form Ag - Ag dimers with a distance of 3.03–3.07. Crystalchemical analysis of known structures containing [Pd(NO₂)₄]^2- complex anions was performed. It has been established that in none of the cases do any of the possible limiting configurations occur.     

Zinc-rich compounds of iron and cobalt: formation of [Fe2Zn(n)] (n = 2-4) and [Co2Zn3] cores

The reactions of heteroleptic GaCp*/CO containing transition metal complexes of iron and cobalt, namely [(CO)(3)M(μ(2)-GaCp*)(m)M(CO)(3)] (Cp* = pentamethylcyclopentadienyl; M = Fe, m = 3; M = Co, m = 2) and [Fe(CO)(4)(GaCp*)], with ZnMe(2) in toluene and the presence of a coordinating co-solvent were investigated. The reaction of the iron complex [Fe(CO)(4)(GaCp*)] with ZnMe(2) in presence of tetrahydrofurane (thf) leads to the dimeric compound [(CO)(4)Fe{μ(2)-Zn(thf)(2)}(2)Fe(CO)(4)] (1). Reaction of [(CO)(3)Fe(μ(2)-GaCp*(3))Fe(CO)(3)] with ZnMe(2) and stoichiometric amounts of thf leads to the formation of [(CO)(3)Fe{μ(2)-Zn(thf)(2)}(2)(μ(2)-ZnMe)(2)Fe(CO)(3)] (2) containing {Zn(thf)(2)} as well as ZnMe ligands. Using pyridine (py) instead of thf leads to [(CO)(3)Fe{μ(2)-Zn(py)(2)}(3)Fe(CO)(3)] (3) via replacement of all GaCp* ligands by three{Zn(py)(2)} groups. In contrast, reaction of [(CO)(3)Co(μ(2)-GaCp*)(2)Co(CO)(3)] with ZnMe(2) in the presence of py or thf leads in both cases to the formation of [(CO)(3)Co{μ(2)-ZnL(2)}(μ(2)-ZnCp*)(2)Co(CO)(3)] (L = py (4), thf (5)) via replacement of GaCp* with {Zn(L)(2)} units as well as Cp* transfer from the gallium to the zinc centre. All compounds were characterised by NMR spectroscopy, IR spectroscopy, single crystal X-ray diffraction and elemental analysis.     

The effect of fluorination: a crystallographic and computational study of mesogenic alkyl 4-[2-(perfluorooctyl)ethoxy]benzoates

The series of alkyl 4-[2-(perfluorooctyl)ethoxy]benzoates (F8-n) shows a systematic change of crystal structures depending on the length of the alkyl chain: separate packing of perfluorooctyl (Rf) and alkyl (Rh) chains from each other for shorter (n=2) and longer (n=11) members, alternate packing of Rf and Rh chains for middle (n=6,7) members, and an intermediate type of packing for n=4. Semiempirical MO calculations show slightly repulsive interactions between the Rf chains, and attractive ones between Rf and Rh chains and between Rh and the core of a molecular pair. It is concluded that fluorination determines the molecular shape of the crystal structures by making the chain rigid. It is confirmed that the interactions between Rf chains are small compared with those between other moieties and that they are forced to aggregate owing to the exclusion from other moieties. Thus, the effect is dependent on the geometries and intermolecular interactions of the other moieties.     

The First Homoleptic Bis(trifluoromethanesulfonyl)amide Complex of Yttrium: [bmim][Y(Tf2N)4]

1‐Butyl‐3‐methylimidazolium tetrakis‐(bis(trifluoromethanesulfonyl)amide)yttrium(III), [bmim][Y(Tf₂N)₄], was obtained from the ionic liquid 1‐butyl‐3‐methylimidazoliumbis(trifluoromethanesulfonyl)amide, [bmim][Tf₂N] and yttrium(III)bis(trifluoromethanesulfonyl)amide, Y(Tf₂N)₃. The crystal structure [monoclinic, C2/c (no. 15), a = 2096.(1), b = 1451.5(1), c = 1608.55(9) pm, β = 109.669(6)°, V = 4608.1(5)·10⁶ pm³, Z = 4, R₁ for 3874 symmetry independent reflections with I₀>2σ(I₀): 0.0438] contains Y^III coordinated by four Tf₂N‐ligands which all adopt a transoid‐conformation with respect to their –CF₃ groups. The oxygen coordination polyhedron around Y^III can be best described as a trigonal dodecahedron.One 1‐butyl‐3‐methylimidazolium cation compensates for the charge of the complex [Y(Tf₂N)₄]^? anion.     

Fluorinations with complex metal fluorides. Part 6 [1] fluorination of yridine and related compounds with caesium tetrafluorocobaltate(III) [2]

Pyridine has been fluorinated over caesium tetrafluorocobaltate(III) (CsCo^IIIF₄) at 300–400°C to give a mixture of undecafluoro-N-methylpyrrolidine, bis(trifluoromethyl)amine, pentafluoropyridine and several polyfluoropyridines; the product composition depended to some extent on the geometry of the reactor. The fluorinations of pentafluoropyridine, piperidine and undecafluoropiperidine were also investigated.     

Acetic acid induced self-assembly of supramolecular compounds [Et4N]3[(WS4Cu2)2(mu-CN)3].2MeCN and [PPh4][WS4Cu3(mu-CN)2].MeCN from preformed clusters [A]2[WS4(CuCN)2] (A = Et4N, PPh4)

Reactions of two preformed trinuclear W/Cu/S clusters, [A](2)[WS(4)(CuCN)(2)] (1: A = Et(4)N; 2: A = PPh(4)), with different concentrations of acetic acid in MeCN generate two interesting 2D polymeric clusters [Et(4)N](3)[(WS(4)Cu(2))(2)(mu-CN)(3)].2MeCN (3), and [PPh(4)][WS(4)Cu(3)(mu-CN)(2)].MeCN (4), respectively. Compound 4 can also be readily obtained in a high yield from the reaction of 2 with equimolar [Cu(MeCN)(4)]PF(6) in MeCN. These compounds have been characterized by elemental analysis, IR spectra, thermal analysis, and single-crystal X-ray diffraction. An X-ray analysis reveals that compound 3 retains the WS(4)Cu(2) cluster core, which serves as a 3-connecting node to link equivalent nodes via single cyanide bridges, forming an anionic 2D (6,3) net. Compound 4 consists of a T-shaped WS(4)Cu(3) core, which also acts as a 3-connecting node, with links to 3 equivalent clusters either through single or double cyanide bridges, affording a different anionic 2D (6,3) network. The acetic acid induced aggregation of 3 and 4 from the two cluster precursors 1 and 2 suggests that this simple synthetic strategy is likely to be applicable to many related systems.     

Outer-sphere association of p-sulfonatothiacalix[4]arene and tetrasulfonatomethylated calix[4]resorcinarene with cobalt(III) tris(dipyridyl): the effect on the spectral and electrochemical properties of the latter

According to the 1H NMR and X-ray data, the outer-sphere association of [Co(dipy)3]3+ with cyclophanic anions p-sulfonatothiacalix[4]arene and tetrasulfonatomethylated calix[4]resorcinarene is accompanied by the inclusion of the dipyridyl moiety of the former into the cavities of the cyclophanic anions in aqueous and aqueous-DMSO solutions and in the solid state. The first-step dissociation of p-sulfonatothiacalix[4]arene does not change the inclusion mode, but the increase in DMSO content leads to a shallower inclusion of [Co(dipy)3]3+. The electrochemical property changes of [Co(dipy)3]3+ with both receptors undergoing ion pairing indicate the stabilization of the tris(dipyridyl) cobalt complexes in lower oxidation states. The effect of the cyclophanic anions on the cyclic voltammograms of [Co(dipy)3]3+ correlates with the efficiency of binding of the latter with tetrasulfonatomethylated calix[4]resorcinarene and p-sulfonatothiacalix[4]arene.     

Synthesis and characterization of [Co(NH3)5NO2][M(NO2)4] (M = Pt, Pd) compounds and their thermolysis products

Compounds [Co(NH₃)₅NO₂][Pd(NO₂)₄] (I) and [Co(NH₃)₅NO₂][Pt(NO₂)₄] · 1.5H₂O (II) have been crystallized from solution. Their crystal structures have been solved, and thermolysis under various conditions studied. The thermolysis products are Co_0.5M_0.5 ordered solid solutions.