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Reactions between XeF2, TiF4 and UV-irradiated elemental F2 in anhydrous HF yielded XeF5TiF5 (XeF6·TiF4), [XeF5]5[Ti10F45] (XeF6·2TiF4), and [XeF5][Ti3F13] (XeF6·3TiF4) upon crystallization. [XeF5]5[Ti10F45] crystallizes in two crystal modifications at low (α-phase, 150 K) and ambient (β-phase, 296 K) temperatures. The crystal structure determination of [XeF5]5[Ti10F45] reveals the largest known discrete decameric [Ti10F45]5− anion built from ten TiF6 octahedra, sharing vertices, in the shape of a double-star. [XeF5]+ cations are completely ordered in the α-phase, while one of three crystallographically unique [XeF5]+ cations is two-fold disordered in the β-phase. The anionic part of [XeF5][Ti3F13] is built from tetrameric Ti4F20 and octameric Ti8F36 units sharing vertices and alternatively linked into ([Ti3F13]−)∞ columns. The charge balance is maintained by [XeF5]+ cations which form secondary Xe⋯F contacts with fluorine atoms of ([Ti3F13]−)∞ groups. The main structural feature of XeF5TiF5 is an infinite chain of distorted TiF6 octahedra joined by cis vertices.

The reactions between group 12 metals and the acidic TaF 5 were studied in the anhydrous HF (aHF) solvent. We were able to prepare and characterize the first compounds containing metal M 2+ cations and undecafluoridodimetallate anions – M(Ta 2 F 11 ) 2 (M = Cd, Hg) without the additional cations, anions or ligands included in the crystal structure. They both crystallize in P -1 space group with cell parameters a = 9.1571(4) A, b = 9.8750(3) A, c = 10.9400(7) A, α = 94.389(4)°, β = 113.124(5)°, γ = 101.142(3)°, V = 879.81(8) A 3 , Z = 2, T = 150 K (Cd(Ta 2 F 11 ) 2 ) and a = 9.1381(5) A, b = 9.8613(6) A, c = 11.4470(7) A, α = 114.086(6)°, β = 102.290(5)°, γ = 100.398(5)°, V = 877.84(11) A 3 , Z = 2, T = 150 K (Hg(Ta 2 F 11 ) 2 ). Metal cations connected through two anions form chains along b axis. M(HF) 2 (TaF 6 ) 2 . nHF (M = Cd, Hg) compounds were also prepared in the MF 2 /TaF 5 (M = Cd, Hg) system and their crystal structures were determined.

Salts containing [Xe2F3]+ cations and [MF6]- anions (M = Ru, Ir) were synthesized by the oxidation of metal with excess of XeF2 in anhydrous hydrogen fluoride (aHF) as a solvent. Single crystals of [Xe2F3][RuF6]∙XeF2, [Xe2F3][RuF6] and [Xe2F3][IrF6] were grown by slow evaporation of the solvent. [Xe2F3][RuF6]∙XeF2 crystallizes in a triclinic P-1 space group (a = 8.3362(1) Å, b = 8.8197(2) Å, c = 9.3026(4) Å; α = 68.27(1) °, β = 63.45(1) °, γ = 82.02 °, V = 568.09(9) Å3 (Z = 2)). Discrete [Xe2F3]+, XeF2 and [RuF6]- units are found in the asymmetric unit. [Xe2F3][RuF6] and [Xe2F3][IrF6] compounds are isostructural and crystalize in a monoclinic C/c space group (a = 14.481(3) Å (Ru); 14.544(3) Å (Ir); b = 8.0837(8) Å (Ru), 8.0808(7) Å (Ir), c = 10.952(2) Å (Ru), 11.014(2) Å (Ir); β = 136.825(6) ° (Ru), 139.954(7) °,V = 877.2(3) Å3 (Ru), 883.6(3) Å3 (Ir); Z = 4). The asymmetric unit in the [Xe2F3][MF6] (M = Ru, Ir) consists of one [Xe2F3]+ and one [MF6]- unit.

A missed cis isomeric form of a well-known trans-[CuCl2(DMSO)2]n complex has been prepared via the tetranuclear [Cu4Cl8(DMSO)8(hmta)] complex. Structurally, both complexes were found to be molecular i.e. [Cu4Cl8(DMSO)8(hmta)] consists of isolated tetracoordinated hexamethylenetetramine molecules, whereas the cis-complex consists of isolated [(DMSO)2ClCuII(μ-Cl)2CuIICl(DMSO)2] clusters. It should also be noted that the cis-configuration of DMSO molecules in [(DMSO)2ClCuII(μ-Cl)2CuIICl(DMSO)2] was directly transferred from that of [Cu4Cl8(DMSO)8(hmta)], while the trans-[CuCl2(DMSO)2]n isomer was always formed as a final stable product.

Qualitative single crystals of π-complexes Cu(H+L)(ClO4)]ClO4 · H2O (I), Cu(H+L)(BF4)]BF4 · H2O (II), and [Cu(H+L)(H2O)]SiF6 · H2O (III) are synthesized from solutions of 3-(diallylamino)propanenitrile (L) in propanol, ethanol, and methanol-water acidified with the corresponding acid to pH 3.5–5 and from the copper(II) salts (Cu(ClO4)2 · 6H2O, Cu(BF4)2 · 6H2O, and CuSiF6 · 4H2O) using the alternating-current electrochemical method on copper wire electrodes. The crystal structures of the complexes are determined. All compounds crystallize in the monoclinic crystal system: complexes I and II are isostructural, space group P21/n, Z = 4. For compound III, space group P21/c, Z = 8. Unit cell parameters: for Ia =7.8153(3), b = 16.7824(7), c = 12.4426(5) A, β = 93.410(2)°, V = 1629.1(1) A3; for II, a = 7.6755(4), b = 16.7119(7), c = 12.3784(6) A, β = 94.354(2)°, V = 1583.2(1); and for IIIa = 9.826(2), b = 24.009(3), c = 12.061(2) A, β = 91.820(6)°, V = 2843.9(7) A3. The trigonal pyramidal coordination of the copper atom in complexes I-III is formed by two C=C bonds of the allyl groups of H+L, the nitrile N atom of the adjacent cation of the ligand, and the O or F atom of the ClO4− or BF4− anions. In structure III, the apical position of the pyramid is occupied by the O atom of the water molecule, since the SiF62− anion is considerably remote from the copper(I) atom. However, this anion is bound to the organic cation by hydrogen bonds F…H (2.05–2.51 A).

The alternating current electrochemical synthesis starting from ethanol solution of Cu(ClO 4 ) 2 ·6H 2 O, CuSO 4 ·5H 2 O and Cu(BF 4 ) 2 ·6H 2 O with the equimolar mixture of 1- and 2-allylbenzotriazole (all-bta) has led to a formation of Cu[2-all-bta]ClO 4 ( I ), Cu[2-all-bta]HSO 4 ( II ) and Cu[2-all-bta]BF 4 ·H 2 O ( III ) compounds. The direct interaction between Cu(ClO 4 ) 2 ·6H 2 O and the mixture of 1- and 2-allylbenzotriazole in ethanol solution results in an appearance of Cu[(1-all-bta)(2-all-bta)]ClO 4 ( IV ) compound. These results are strikingly different from earlier performed syntheses using the same ligands mixture and copper(II) halides, and producing coordination compounds with 1-allylbenzotriazole only. Compounds I and II are isotypical and crystallize in a monoclinic space group Cc . I : a = 9.5413(10) A, b = 12.3171(9) A, c = 10.3264(10) A, β = 111.155(4)°, V = 1131.78(18) A 3 , Z = 4. II : a = 9.1707(17) A, b = 13.6639(17) A, c = 9.4543(17) A, β = 105.555(7)°, V = 1141.3(3) A 3 , Z = 4. The main feature of structures I and II is a chelate-bridging role of the ligand moiety, bonded to one copper ion via C C-bond of the allyl group and nitrogen atom of the triazole core, and to the second Cu + centre by another N atom. Trigonal-pyramidal copper environment comprises of two nitrogen atoms from different ligand units, C C-bond and oxygen atom at the apical position. The bridging function of both Cu + cations and 2-all-bta molecules results in the formation of infinite chains. High affinity of BF 4 − anion to the H 2 O leads to a formation of compound III including water molecule. It crystallizes in an orthorhombic Pbca space group, a = 13.502(8) A b = 11.299(5) A c = 16.124(8) A, V = 2460(2) A 3 , Z = 8. The ligand moiety plays the same as in I and II chelate-bridging function, but Cu + , being also bonded to C C group and to two N atoms, is connected with the disordered BF 4 − anion through the water bridge. In the crystal structure IV the metal ion possesses mixed-isomer surrounding, being bound to N-atom and C C-bond of 2-all-bta molecule, N-atom of 1-all-bta-moiety and O(ClO 4 − ) atom at apical position. IR spectra confirm rather effective Cu–(C C) bonding.

The lead fluoridooxidovanadates(V), Pb(V2O2F8) and Pb(VOF5), were synthesized from PbF2 and VOF3 in anhydrous HF. Their crystal structures were determined and Raman spectra recorded. Compound Pb3F(V4O3F18) with a novel mixed valent vanadium(IV, V) fluoridooxido anion, V4O3F185–, obtained as a by-product, was also structurally characterized.

The H3OM[AsF6]3 (M = Fe, Zn), H3OMF[AsF6]2 (M = Fe, Cu) and (H3O)2Hg2F[AsF6]5 compounds were prepared by treatment of the corresponding divalent oxide MO (M = Zn, Cu, Hg) with AsF5 in anhydrous HF (aHF) or by reaction between H3OAsF6, FeF2 and AsF5 in aHF. The H3OM[AsF6]3 (M = Fe, Zn) compounds crystallize isotypically to previously known compounds where M is Mn, Co and Ni. The H3OMF[AsF6]2 (M = Fe, Cu) crystal structures consist of one-dimensional infinite zig-zag [–M–F–M–] chains. Each M2+ is additionally bridged by two pairs of [AsF6] units with neighbouring M2+ atoms forming columns along the y axis. [H3O]+ cations are placed between the columns. In H3OCuF[AsF6]2 each of the Cu atoms is coordinated by six fluorine atoms {2 × 1.850(2) A within the [–Cu–F–Cu–] chains and four Cu–F(As) bonds with 2 × 2.067(4) A and 2 × 2.254(5) A}. There is a pronounced antiferromagnetic coupling (J/kB = –150 K) within the [–Cu–F–Cu–] chains. In H3OFeF[AsF6]2 the corresponding values are 2 × 1.919(2) A, 2 × 2.184(3) A and 2 × 2.208(4) A. (H3O)2Hg2F[AsF6]5 crystallizes isotypically to previously known (H3O)2Cd2F[SbF6]5. No oxonium–M2+–[AsF6]– salts were observed when M was Ti, V, Cr, Nb, Pd, Ag, Cd, Sn and Pb.

Complex [Cu(CN)(NC(CH2)2O(CH2)2O(CH2)2CN))] is obtained by the heating of copper(I) cyanide with 3,3′-[ethane-1,2-diylbis(oxy)]dipropanenitrile (DPN) followed by slow cooling. The X-ray diffraction analysis shows that the crystals are monoclinic, space group C2/c, a = 12.183(2), b = 10.667(2), c = 8.4700(13) A, β = 92.444(10)°, V = 1099.7(3) A3, Z = 4. The structure is built of infinite zigzag fragments [Cu(CN)(DPN)]n. The tetrahedral environment of the copper atom includes two cyano groups of the ligand and two cyano groups of the inorganic fragment.

[Cu2(C6H4N3(C3H5))2(H2O)2SiF6]·2H2O (I) and [Cu2(C6H4N3(C3H5))2(CH3OH)2(H2O)2]SiF6 (II) π-compounds were obtained by alternating current electrochemical synthesis, starting from ethanol–methanol solution containing 1-allylbenzotriazole, H2SiF6, CuSiF6·4H2O and copper wire electrodes. Both compounds were X-ray structurally investigated. In complex I a mid-point of the C C bond of one 1-allylbenzotriazole (L) molecule, the nitrogen atom from another L moiety, the oxygen atom from a water molecule and the fluorine atom from a SiF 6 2 - anion form the trigonal-pyramidal environment of the CuI center. One more water molecule is fixed in the crystal space by strong O–H⋯F and O–H⋯O hydrogen bonds. The bridging function of the L, Cu+ and SiF 6 2 - units results in a formation of infinite metal-organic layers. The metal surrounding in II differs from that in I by a presence of oxygen atom from the methanol molecule instead of fluorine atom from the SiF 6 2 - anion. An appearance of ⋯ SiF 6 2 - –CH3OH–Cu+–L–Cu+–H2O⋯ infinite layers in II instead of ⋯ SiF 6 2 - –Cu+–L–Cu+⋯ in I leads to a noticeable elongation of the unit cell of II along [0 1 0] direction in comparison with I. The structure I represents the first known example of the Cu+– SiF 6 2 - bond.

Hg(AuF 6 ) 2 crystallizes at 200 K in the orthorhombic space group Pbcn (No. 60) with a = 917.67(7) pm, b = 971.59(8) pm, c = 962.04(8) pm, and Z = 4. Mercury atoms are coordinated by eight fluorine atoms with six short and two long Hg–F contacts. HgF 8 polyhedra share their four vertices and two edges with six AuF 6 units forming a tridimensional framework. The results of X-ray diffraction analysis on single crystals of AgFAuF 6 are in agreement with previously known powder X-ray diffraction data (Casteel et al, J. Solid State Chem. 96 (1992) 84–96). AgFAuF 6 crystallizes orthorhombic in the space group Pnma (No. 62), a = 717.06(7) pm, b = 761.67(7) pm, c = 1013.61(10) pm at 200 K, Z = 4.

The compounds, Cd(BF 4 )(TaF 6 ) and Cd(BF 4 )(BiF 6 ), have been synthesized and characterized by single-crystal X-ray diffraction and Raman spectroscopy. Both isostructural compounds crystallize in the monoclinic P2 1 /c space group with a = 8.2700(6) A, b = 9.3691(6) A, c = 8.8896(7) A, β = 94.196(3)°, V = 686.94(9) A 3 for Cd(BF 4 )(TaF 6 ) and a = 8.3412(8) A, b = 9.4062(8) A, c = 8.9570(7) A, β = 93.320(5)°, V = 701.58(11) A 3 for Cd(BF 4 )(BiF 6 ). Eight fluorine atoms (4 BF 4 − + 4 AF 6 − ) form a surrounding around the cadmium atom in the shape of distorted square antiprism. These compounds are not isostructural with mixed-anion analogues of Ca, Sr, Ba and Pb studied earlier.

3,5-Diamino-1,2,4-triazolium tetrafluoroborate (LH)BF 4 and hexafluorosilicate (LH) 2 SiF 6 have been isolated and characterized by single-crystal X-ray structure determination, IR spectroscopy, mass spectrometry, solubility data, potentiometry. The N–H⋯F and N–H⋯N hydrogen bonds play an important role in a formation of 3-D structures of two compounds. The relationship between the salts structure and some properties is discussed.

Crystals grown from anhydrous HF solutions of CsAsF 6 and Cs 2 B 12 F 12 or KAsF 6 and Cs 2 B 12 F 12 are shown by Raman spectroscopy and single-crystal X-ray diffraction to be the ternary salts K 3 (AsF 6 )(B 12 F 12 ) or Cs 3 (AsF 6 )(B 12 F 12 ). Both compounds exhibit a modified version of the anti-perovskite structure. They are rare examples of crystals that simultaneously contain octahedral and icosahedral molecular species and are also rare examples of salts containing fluoroanions with different shapes and charges. The crystallographic results show that both compounds are densely packed.

AgBF 4 , in aqueous solution, reacts with 1,3,5-triallyl-1,3,5-triazine-2,4,6 (1H,3H,5H)-trione (TTT) yielding Ag[C 3 O 3 (NC 3 H 5 ) 3 ]BF 4 ·H 2 O ( I ). It crystallizes in the monoclinic space group P 2 1 / n , a = 13.356(3) A, b = 9.4264(17) A, c = 13.360(3) A, β = 94.057(2)°, V = 1677.8(5) A 3 , and Z = 4. In the crystal structure I , Ag + is coordinated by two C C groups from two TTT molecules, one O atom from a water molecule and one more distant O atom from the triazine ring, markedly shifted from the ideal apical position. The TTT molecule uses only two allyl groups for metal bonding. The bridging role of the Ag + cations and the TTT molecules results in the formation of infinite {Ag[C 3 O 3 (NC 3 H 5 ) 3 ]·H 2 O} n chains. The Raman spectrum of I supports weak Ag–(C C) bonding.

The crystal structure of IF6[Ag(SbF6)3] has been determined by X-ray single crystal and X-ray powder diffraction analysis. The structure consists from [Ag(SbF6)3]– chains and [IF6]+ cations placed between them. Ag2+ is found in regular octahedral coordination of six fluorine atoms [Ag–F = 6 × 2.170(12) A]. EXAFS analysis of Jahn–Teller distortions in IF6[Ag(SbF6)3] shows that Ag2+ surrounding is elongated octahedral at room temperature. EXAFS signals are fitted with four short and two long Ag–F distances [4 × 2.11(1) A; 2 × 2.40(2) A]. This result is in apparent contradiction with X-ray diffraction studies where the [AgF6] moiety appears to be a regular octahedra. The Raman spectrum of IF6[Ag(SbF6)3] is in agreement with the presence of regular IF6 and deformed SbF6 groups.

The paper is dealing with the two sets of the coordination compounds: (a) the coordination compounds in which anhydrous HF is acting as a ligand to the metal ions (b) the compounds in which poly(hydrogen–fluoride) anions of the type H n F n +1 − ( n = 1, 2, 3) are coordinated to the metal centers and connecting them in the 3D structures. The main purpose of this work is the review of the above mentioned compounds which were recently isolated in our laboratory. The coordination of the metal centers and their connection in the three-dimensional network are illustrated with their crystal structures. A very brief review of the achievements of some other groups is also mentioned where it is appropriate.

Rare earth trifluorides (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, and Dy) react with boron trifluoride in anhydrous hydrogen fluoride (aHF) at room temperature. Products were found to be only sparingly soluble in aHF where the solubility decreases from lanthanum to dysprosium. After an excess of BF3 and aHF were pumped away at ambient temperature, LnF(HF)(BF4)2 type of compounds were isolated. Single crystals of LnF(HF)(BF4)2 (Ln = Pr, Nd) and La(BF4)3 were grown for 3–5 months from solutions of LnF3 (Ln = La, Pr) and Nd2O3 in aHF under pressure of BF3 (4 bar). Structures consist from the zig-zag [–Ln–F–Ln–] (Ln = Pr, Nd) chains connected via BF4 units and HF molecules into tridimensional network. The Ln–F(Ln) distances are significantly shorter [2.2489(6) A for Pr and 2.234(1) A for Nd] than Ln–F(BF4–) and Ln–F(HF) ones [Pr: 2.461(4)–2.528(5) A, Nd : 2.446(7)–2.511(9) A]. In La(BF4)3, the lanthanum atoms are coordinated by nine fluorine atoms with seven shorter La–F distances [2.410(2)–2.485(2) A] and two elongated ones [2.600(2) A]. The vibrational spectra of isolated rare earth tetrafluoroborates show strong deviations of the [BF4]– anions from ideal Td symmetry. Because of the strong cation-anion interactions, the splittings of the anion vibrational modes are observed indicating rather covalent character of the bonding between LnF3 and BF3.

In the system BaF2/BF3/PF5/anhydrous hydrogen fluoride (aHF) a compound Ba(BF4)(PF6) was isolated and characterized by Raman spectroscopy and X-ray diffraction on the single crystal. Ba(BF4)(PF6) crystallizes in a hexagonal P 6 ¯ 2 m space group with a=10.2251(4) A, c=6.1535(4) A, V=557.17(5) A3 at 200 K, and Z=3. Both crystallographically independent Ba atoms possess coordination polyhedra in the shape of tri-capped trigonal prisms, which include F atoms from BF4− and PF6− anions. In the analogous system with AsF5 instead of PF5 the compound Ba(BF4)(AsF6) was isolated and characterized. It crystallizes in an orthorhombic Pnma space group with a=10.415(2) A, b=6.325(3) A, c=11.8297(17) A, V=779.3(4) A3 at 200 K, and Z=4. The coordination around Ba atom is in the shape of slightly distorted tri-capped trigonal prism which includes five F atoms from AsF6− and four F atoms from BF4− anions. When the system BaF2/BF3/AsF5/aHF is made basic with an extra addition of BaF2, the compound Ba2(BF4)2(AsF6)(H3F4) was obtained. It crystallizes in a hexagonal P63/mmc space group with a=6.8709(9) A, c=17.327(8) A, V=708.4(4) A3 at 200 K, and Z=2. The barium environment in the shape of tetra-capped distorted trigonal prism involves 10 F atoms from four BF4−, three AsF6− and three H3F4− anions. All F atoms, except the central atom in H3F4 moiety, act as μ2-bridges yielding a complex 3-D structural network.

The complex [XeF 5 ] 3 [Ti 4 F 19 ] was prepared by reaction of XeF 2 , TiF 4 and UV-irradiated elemental fluorine in anhydrous hydrogen fluoride as the solvent. The crystal structure of [XeF 5 ] 3 [Ti 4 F 19 consists of [XeF 5 ] + cations and discrete [Ti 4 F 19 ] 3- anions. The [XeF 5] units have usual slightly distorted pseudo-octahedral symmetry. Contrary to the previously reported [Ti 4 F 18 ] 2- anion, where each TiF 6 octahedron shares three apexes with three other octahedra, in [Ti 4 F 19 ] 3- , only two μ 3- [TiF 6] octahedra share three apexes with three other [TiF 6 ] units. Each of the remaining two μ 2 -[TiF 6 ] octahedra shares only two vertices with two of the above-mentioned μ 3 -[TiF 6 ] moieties. The Raman spectrum of [XeF 5 ] 3 -[Ti 4 F 19 ] is in agreement with the presence of [XeF 5 ] + cations and [Ti 4 F 19 ] 3- anions.

Three novel heterometallic complexes [Cu(en) 2 Cr(NCS) 4 (NH 3 ) 2 ][Cr(NCS) 4 (NH 3 ) 2 ] · 6dmf ( 1 ), [Cu(en) 2 Cr(NCS) 4 (NH 3 ) 2 ](OAc) ( 2 ) and [{Cu(en) 2 } 3 {Cr(NCS) 4 (NH 3 ) 2 } 2 (NCS) 2 ](NCS) 2 ( 3 ) have been synthesized in a one-pot reaction from copper powder, Reineckes salt, NH 4 X [X − = OAc − ( 2 ), NCS − ( 3 )] in a dmf ( 1 ) or CH 3 CN ( 2 , 3 ) solution of ethylenediamine (en). X-ray studies showed that 1 and 2 consist of cationic polymeric chains, formed by Cu ( en ) 2 2 + and Cr ( NCS ) 4 ( NH 3 ) 2 - building blocks that bridged through thiocyanate anions. In both complexes, distinct hydrogen bonds are present and serve to increase the dimensionality of the compound from one to two (in 1 ) or three (in 2 ). The main structural feature of 3 is the pentanuclear Cu 3 Cr 2 cation which is H-bonded with uncoordinated thiocyanate groups generating a 3D supramolecular assembly. The shortest Cu⋯Cr distances are 5.840(1) A for 1 , 5.856(1) and 6.018(3) A for 2 and 6.009(9) and 6.465(9) A for 3 . Compounds 1 and 2 are essentially paramagnets whereas compound 3 shows a weak antiferromagnetic coupling. The magnetic properties are simulated and discussed in terms of the structural features.

ANi(AsF 6 ) 3 (A = O 2 + , NO + , NH 4 + ) compounds could be prepared by reaction between corresponding AAsF 6 salts and Ni(AsF 6 ) 2 . When mixtures of AF (A = Li, Na, K, Rb, Cs) and NiF 2 are dissolved in aHF acidified with an excess of AsF 5 the corresponding AAsF 6 and Ni(AsF 6 ) 2 were formed in situ. For A = Li and Na only mixtures of AAsF 6 and Ni(AsF 6 ) 2 were obtained, while for A = K, Rb and Cs, the final products were ANi(AsF 6 ) 3 (A = K–Cs) compounds contaminated with AAsF 6 (A = K–Cs) and Ni(AsF 6 ) 2 . ANi(AsF 6 ) 3 (A = H 3 O + , O 2 + , NO + , NH 4 + and K + ) compounds are structurally related to previously known H 3 OCo(AsF 6 ) 3 . The main features of the structure of these compounds are rings of NiF 6 octahedra sharing apexes with AsF 6 octahedra connected into infinite tri-dimensional network. In this arrangement cavities are formed where single charged cations are placed. In O 2 Ni(AsF 6 ) 3 the vibrational band belonging to O 2 + vibration is found at 1866 cm −1 , which is according to the literature data one of the highest known values, and it is only 10 cm −1 lower than the value for free O 2 + .

In the system BaF2/PF5/XeF2/anhydrous hydrogen fluoride a new coordination compound, [Ba(XeF2)4](PF6)2, was isolated. The XeF2 molecules are interacting as ligands directly with the Ba2+ cations. The compound crystallizes in the triclinic space group P 1 ¯ with a = 8.739(2) A, b = 8.912(2) A, c = 25.855(7) A, α = 76.331(6), β = 83.085(6), γ = 81.212(6), V = 1926.2(8) A3 at 200 K and Z = 4. The structure consists of two crystallographically independent barium atoms with the coordination numbers 10 and 12. The barium atoms and the bridging XeF2 molecules form double layers which are further interconnected into the 3-D network by the weak Xe⋯F (PF6−) interactions. The Raman spectrum of [Ba(XeF2)4](PF6)2 clearly shows the presence of bridging XeF2 molecules.

Three new compounds Ca(HF2)2, Ba4F4(HF2)(PF6)3 and Pb2F2(HF2)(PF6) were obtained in the system metal(II) fluoride and anhydrous HF (aHF) acidified with excessive PF5. The obtained polymeric solids are slightly soluble in aHF and they crystallize out of their aHF solutions. Ca(HF2)2 was prepared by simply dissolving CaF2 in a neutral aHF. It represents the second known compound with homoleptic HF environment of the central atom besides Ba(H3F4)2. The compounds Ba4F4(HF2)(PF6)3 and Pb2F2(HF2)(PF6) represent two additional examples of the formation of a polymeric zigzag ladder or ribbon composed of metal cation and fluoride anion (MF+)n besides PbF(AsF6), the first isolated compound with such zigzag ladder. The obtained new compounds were characterized by X-ray single crystal diffraction method and partly by Raman spectroscopy. Ba4F4(HF2)(PF6)3 crystallizes in a triclinic space group P1¯ with a=4.5870(2) A, b=8.8327(3) A, c=11.2489(3) A, α=67.758(9)°, β=84.722(12), γ=78.283(12)°, V=413.00(3) A3 at 200 K, Z=1 and R=0.0588. Pb2F2(HF2)(PF6) at 200 K: space group P1¯, a=4.5722(19) A, b=4.763(2) A, c=8.818(4) A, α=86.967(10)°, β=76.774(10)°, γ=83.230(12)°, V=185.55(14) A3, Z=1 and R=0.0937. Pb2F2(HF2)(PF6) at 293 K: space group P1¯, a=4.586(2) A, b=4.781(3) A, c=8.831(5) A, α=87.106(13)°, β=76.830(13)°, γ=83.531(11)°, V=187.27(18) A3, Z=1 and R=0.072. Ca(HF2)2 crystallizes in an orthorhombic Fddd space group with a=5.5709(6) A, b=10.1111(9) A, c=10.5945(10) A, V=596.77(10) A3 at 200 K, Z=8 and R=0.028.

A novel supramolecular assembly [{Cu(enac)}2Cr(NCS)4(NH3)2][Cr(NCS)4(NH3)2]3 · 4(CH3)2CO (enac = 4,6,6-trimethyl-3,7-diazanon-3-ene-1,9-diamine), the first example of a Cu/Cr heterometallic compound containing a Schiff-base ligand such as enac, and an anion of Reineckes salt, Cr(NCS)4(NH3)2−, as a building block, was obtained by the self-assembly reaction of copper powder and Reineckes salt in an acetone/methanol (1:4) solution of ethylenediamine in the open air. An X-ray study shows that the complex includes a trinuclear Cu2Cr cation, constructed from two Cu(enac)2+ moieties and a trans-[Cr(NCS)4(NH3)2]− block as a two-linking bridging ligand. The metal–metal separations within the cation are Cu⋯Cr = 6.393(31) A and Cu⋯Cu = 12.786(63) A. The supramolecular architecture of the complex involves two types of H-bonded chains, the first chain is generated by trinuclear cations [{Cu(enac)}2Cr(NCS)4(NH3)2]2+, [Cr(NCS)4(NH3)2]− anions and (CH3)2CO molecules, while the second by crystallographically different anions of Reineckes salt and (CH3)2CO. Variable-temperature (1.8–300 K) magnetic susceptibilities show a slight change of the μB value at low temperature, indicative of weak antiferromagnetic interactions (JCuCr = −0.9 cm−1) between the paramagnetic centers.

The compounds ACrF 6 (A = Li-Cs) were prepared by photochemical reactions of AF/CrF 3 mixtures in anhydrous HF with elemental F 2 at ambient temperature. The crystal structures of compounds ACrF 6 (A = K-Cs) are analogous to that of KOsF 6 , and NaCrF 6 exhibits polymorphism. The trigonal phase (II) can be classified to have the well-known LiSbF 6 type of structure, while the crystal structure of the orthorhombic modification (I) appears to be a new structure-type. Thermal decomposition of the ACrF 6 salts produce ACrF 5 (A = Rb, Cs), ACrF 5 /A 2 CrF 6 (A = K), or A 2 CrF 6 (A = Li, Na). These compounds undergo partial solvolysis in anhydrous HF with precipitation of CrF 4 . From the remaining solutions of the [CrF 6 ] 2- anions and dissolved AF (A = Li-Cs), single crystals of ACrF 5 (A = K-Cs), A 2 CrF 6 ·2HF (A = Na, K), A 2 CrF 6 ·4HF (A = Rb, Cs), Li 2 CrF 6 , and K 3 Cr 2 F 11 ·2HF were grown, and their crystal structures determined. The main structural feature of the ACrF 5 compounds is the infinite zigzag [CrF 5 ] n n- chain of distorted [CrF 6 ] octahedra joined by cis vertices. The crystal structures of A 2 CrF 6 ·2HF (A = Na, K) and A 2 CrF 6 ·4HF (A = Rb, Cs) consist of distorted [CrF 6 ] 2- octahedra involved in moderate to strong hydrogen bonding with HF molecules, while two A + cations compensate the negative charge of each octahedron. In Na 2 CrF 6 ·2HF, two neighboring HF molecules are involved in moderate to strong hydrogen bonding with each other. (HF) 2 dimers with a parallelogram structure are formed. The mutual interactions in the crystal structure of K 2 CrF 6 ·2HF differ from those found in Na 2 CrF 6 ·2HF. In the former, each HF molecule interacts with the [CrF 6 ] 2- anion and three K + cations. A 2 CrF 6 ·4HF compounds of Rb and Cs are isostructural. Their structures consist of A + cations and [CrF 6 ] 2- anions involved in hydrogen bonding with two sets of HF molecules in the trans position. The crystal structure of K 3 Cr 2 F 11 ·2HF reveals a rare case of the [M 2 F 11 ] 3- anion.

The crystal structures of InPF6, TlPF6, InAsF6 and TlAsF6 have been determined from single-crystal X-ray diffraction data collected at 200 K. InPF6 and TlPF6 crystallize in the cubic space group F m 3 ¯ m (No. 225) with a = 7.966(18) A, V = 506(2) A3 (In) and a = 7.9203(19) A, V = 496.8(2) A3 (Tl), Z = 4, while InAsF6 and TlAsF6 crystallize in a rhombohedral space group R 3 ¯ (No. 148) with a = 7.5029(13) A, c = 7.7462(19) A, V = 377.64(13) A3 (In) and a = 7.5084(9) A, c = 7.6743(9) A, V = 374.68(8) A3 (Tl), Z = 3. In [AsF6]− salts, In+ and Tl+ cations are coordinated by 12 F atoms. In the crystal structures of InPF6 and TlPF6 disordered [PF6]− anions are present.

The reaction of Ba(NbF6)2 and excess XeF2 in anhydrous HF at room temperature yields [Ba(XeF2)5](NbF6)2. This is the first example of the coordination compound with XeF2 molecule as a ligand and NbF6- anion. It crystallizes in the orthorhombic space group Fmmm, with a = 12.084(6) Å, b = 13.646(7) Å, c = 13.927(7) Å, V = 2297(2) Å3, and Z = 4. The reaction of XeF2·Xe2F3·RuF6 and BaF2 in anhydrous HF yields [Ba(XeF2)5](RuF6)2 - the first example of the coordination compound containing RuF6- anion and XeF2 molecules. It appears to be isostructural with [Ba(XeF2)5](NbF6)2, with a = 11.9510(14) Å, b = 13.5174(14) Å, c = 13.8488(12) Å, V = 2237.2(4) Å3, and Z = 4. The Raman spectra of both compounds prove that all the XeF2 molecules are symmetrical. Four XeF2 molecules per formula unit act as bridges between Ba centres, while one molecule is held in the structure by electrostatic forces. In the series of compounds [Ba(XeF2)5](AF6)2 with A = As, Sb, Ru, Nb, the influence of the anions AF6- was analyzed.

The reaction of 2-amino-benzothiazole with allyl bromide resulted in a mixture of 2-imino-3-allyl-benzothiazole and 2-imino-3-allyl-benzothiazolium bromide.Using such a mixture and copper(II) chloride in acetonitrile solution in alternating-current electrochemical synthesis crystals of the [(CuCl)C10H10SN2] (I) have been obtained. The same procedure, performed in ethanol solution, has led to formation of [C10H11SN2+]2[Cu2Cl4]2− (II). In the same manner the bromine derivative [C10H11SN2+]2[Cu2Br4]2− (III) has been synthesized. All three compounds were X-ray structurally investigated. I:monoclinic space group P21/n, a = 13.789(6), b = 6.297(3), c = 13.830(6) A, β = 112.975(4)°, V = 1105.6 (9) A3, Z = 4 for CuCl·C10H10 SN2 composition. Compounds II and III are isomorphous and crystallize in triclinic space group. II a = 7.377(3), b = 8.506(3), c = 9.998(4) A, α = 79.892(10)°, β = 82.704(13)°, γ = 78.206(12)°, V = 601.9(4) A3, Z = 1. III a = 7.329(2), b = 8.766(3), c = 10.265(3) A, α = 79.253(9)°, β = 82.625(9)°, γ = 77.963(9)°, V = 630.9(3) A3, Z = 1. In the structure I [(CuCl)C10H10SN2] building blocks are bound into infinitive spiral-like chains via strong N-H..Cl hydrogen bonds. In the zwitter-ionic II and III compounds copper and halide atoms form centrosymmetric [Cu2X4]2− anions, which are interconnected via N-H..X hydrogen bonds into infinite butterfly-like chains. The strongest Cu-(C=C) π-interaction has been observed in structure I, where copper possesses coordination number 3. Increasing copper coordination number to 4 in II as well as replacing chlorine atoms by bromine ones in III suppresses markedly this interaction.

The crystalline complex ImH[CuCl2(HOCH2C≡CCH2OH)] has been synthesized by the direct interaction of 2-butyne-1,4-diol with CuCl in concentrated aqueous solution of (ImH)Cl (ImH+ is imidazolium cation) and studied by X-ray crystallography. The crystals are triclinic, space group P \(\overline 1 \), a = 7.08(2) A, b = 7.49(1) A, c = 10.962(8) A, α = 101.76(8)°, β = 95.85(8)°, γ = 99.57(8)°, Z = 2. The structure consists of stacks of discrete anions [CuCl2(HOCH2C≡CCH2OH)]− arranged along the [100] axis and [ImH]+ cations occupying the free space. The environment of π-coordinated Cu(I) atoms is trigonal and consists of two chlorine atoms and the C≡C bond of 2-butyne-1,4-diol molecule. The alcohol groups do not participate in the coordination, but they form strong hydrogen bonds N-H···O (H···O, 1.76(6) A) and O-H···Cl(H···Cl, 2.29(5) A).

Compounds (III) (yield given in g) and (IV) are synthesized in anhydrous HF and their crystal structures are determined by single crystal XRD.

HgFAsF6 is prepared by oxidation of Hg2(AsF6)2 (prepared via the reaction of Hg and AsF5 in liquid SO2) with fluorine in anhydrous HF condensed on the sample at 77 K (T-shaped FEP tubes, 25 °C, 2 d).

The title compounds are prepared according to the literature and used for single crystal growth in a T-shaped fluoroethylene-hexafluoropropylene crystallization apparatus.

Pb(SbF6)2 and Ba(SbF6)2 and PbFSbF6 are prepared by reaction of the corresponding metal difluorides, SbF3, anhydrous HF, and excess elemental F2 (fluoroethylene-hexafluoropropylene reaction vessels, 25 °C).

Revealing the relaxation mechanisms of hidden states in transition metal dichalcogenides leads to control of metastability., Controllable switching between metastable macroscopic quantum states under nonequilibrium conditions induced either by light or with an external electric field is rapidly becoming of great fundamental interest. We investigate the relaxation properties of a “hidden” (H) charge density wave (CDW) state in thin single crystals of the layered dichalcogenide 1T-TaS2, which can be reached by either a single 35-fs optical laser pulse or an ~30-ps electrical pulse. From measurements of the temperature dependence of the resistivity under different excitation conditions, we find that the metallic H state relaxes to the insulating Mott ground state through a sequence of intermediate metastable states via discrete jumps over a “Devil’s staircase.” In between the discrete steps, an underlying glassy relaxation process is observed, which arises because of reciprocal-space commensurability frustration between the CDW and the underlying lattice. We show that the metastable state relaxation rate may be externally stabilized by substrate strain, thus opening the way to the design of nonvolatile ultrafast high-temperature memory devices based on switching between CDW states with large intrinsic differences in electrical resistance.

Compounds (III) and (V) (yields given in mg) are characterized by single crystal XRD and Raman spectroscopy.

In this review an exhaustive crystallochemical analysis of copper(I) π-complexes with allyl derivatives of heterocyclic compounds has been performed. Structural genesis of inorganic constituents starting from the simplest units to the most complicated aggregates was considered taking into account the specific role of Cu-(C=C) interaction, the construction of the organic ligands, the basicity and nucleophilic activity of their heteroatoms, as well as olefin Cu(I) π-complex preparation route.

Thermal reaction between XeF2 and excess TiF4 (evacuated reaction vessel, -196 +135 °C, 12 h) results in the formation of the highly ionized XeII species [Xe2F3][Ti8F33] (I) and [XeF]2[Ti9F38] (II) which represent [Xe2F3]+ and [XeF]+ compounds differing from known XeII salts containing discrete F- anions with pentavalent metalloid/metal centers.

[Cu(XeF 2 ) 6 ](SbF 6 ) 2 crystallizes in the rhombohedral symmetry with a = 1003.6(2) pm, c = 2246.5(12) pm at 200 K and Z = 3, space group R 3 ¯ (No. 148). [Zn(XeF 2 ) 6 ](SbF 6 ) 2 is isostructural to [Cu(XeF 2 ) 6 ](SbF 6 ) 2 with a = 1007(2) pm and c = 2243(6) pm. The structures are characterized by isolated homoleptic [M(XeF 2 ) 6 ] 2+ (M = Cu, Zn) cations and of [SbF 6 ] − octahedra. Reactions of M(SbF 6 ) 2 (M = Cu, Zn) with XeF 2 in anhydrous hydrogen fluoride (aHF) and reactions of MF 2 with Xe 2 F 3 SbF 6 in aHF always yield a mixture of [M(XeF 2 ) 6 ](SbF 6 ) 2 , Xe 2 F 3 SbF 6 and MF 2 .

Both compounds of CuBr⋅C6H4N3(OC3H5) (sp. gr. P1, a = 7.633(1) A, b = 9.987(1) A, c = 14.898(2) A, α = 104.75(1)∘, β = 94.76(1)∘, γ = 106.90(1)∘) (I) and 2CuCl⋅C6H4N3(OC3H5) (sp. gr. Cc, a = 11.2483(4) A, b = 16.7076(6) A, c = 7.2948(3) A, β = 118.612(2)∘) (II) composition were prepared by alternating-current electrochemical synthesis. In I due to a bridging function of organic moieties 16-membered cycles appear which are combined into ribbons {Cu2Br2[(C6H4N3(OC3H5)]2} n . Each of two crystallographically independent copper atom possesses a trigonal-pyramidal arrangement with different degree of tetrahedral distortion. Distinctive numbers of hydrogen bonds around Br1 and Br2 atoms cause rather appreciable distinctions in copper–olefinic bond interaction effectiveness for each metal atom. In II Cu2Cl2 rhombs are joined to infinite chains oriented along [010] direction. Each ligand molecule is also coordinated through the C=C—bond of the allylic group to copper atom of one inorganic chain and through the nitrogen atom to a metal atom belonging to another copper-halide chain. Cu1 atoms is tetrahedrally surrounded by three chlorine atoms and nitrogen one, whereas a trigonal-planar arrangement of Cu2 atom is formed by two halogen atoms and slightly disordered olefinic group.

Single crystals of the heterovalent CuI,CuII π,σ-complex Cu7Br6.48Cl1.52 ⋅ 2C3N3(OC3H5)3 are synthesized by the ac electrochemical method from an ethanol solution containing 2,4,6-triallyloxy-1,3,5-triazine, CuCl2 ⋅ 2H2O, and CuBr2. The unit cell parameters of the crystals are: space group \(P\bar 1\), a = 8.271(3) A, b = 11.391(3) A, c = 11.821(3) A, α = 67.43(1)°, β = 84.41(2)°, γ = 85.14(2)°, V = 1022(1) A3, and R(F) = 0.0714. The copper and halogen atoms form unique moieties Cu6X6 linked by bridging fragments [Cu2+ (C3N3(OC3H5)3)2]X2 into infinite chains. Each inorganic moiety Cu6X6 is linked with four 2,4,6-triallyl- oxy-1,3,5-triazine molecules. The ligand molecule is coordinated to one CuII atom through the nitrogen atom of the triazine cycle and to two CuI atoms through the C=C bonds of two allyl groups. The Br content equal to 0.57 in the X(4) position linking the CuI and CuII atoms differs markedly from a value of 0.85–0.91 for the X(1), X(2), and X(3) positions linked only with the Cu(I) atoms.

Single crystals of CuCl · C6H4N3(OC3H5)(I) are synthesized by ac electrochemical method from Cu(II) chloride and 1-allyloxybenzotriazole in ethanol solution and their unit cell parameters are determined: space group P21/a a=11.583(4) A, b=11.443(7) A, c=8.620(4) A, β=108.77(3)°, V=1082(2) A3, R(F)=0.0366, R w (F)=0.0396 for 1095 reflections. In the structure of π-complex I, inorganic fragment Cu2Cl2 forms centrocymmetric parallelogram. A molecule of 1-allyloxybenzotriazole acts as a bridge, which is bonded to the Cu atoms of two inorganic dimers through the C=C bond of the allyl group and to the N atom of a triazole ring. Owing to this bridging function, the ligand molecules form zigzag organometallic layers. The trigonal-pyramidal coordination sphere of a metal atom includes two Cl atoms and the C=C group. The structural motif of complex I significantly differs from that of the previously studied 2CuCl · C6H4N3(OC3H5) and resembles the motif of a bromide analog Cu2Br2 · [C6H4N3(OC3H5)]2.

By alternating-current electrochemical technique crystals of copper(I) π-complex with 1-allylpyridinium chloride of [C5H5N(C3H5)][Cu2Cl3] (1) composition have been obtained and structurally investigated. Compound 1 crystallizes in monoclinic system, space group C2/c a = 24.035(1) A, b = 11.4870(9) A, c = 7.8170(5) A, β = 95.010(5)°, V = 2150.0(2) A3 (at 100 K), Z = 8, R = 0.028, for 4836 independent reflections. In the structure 1 trigonal-pyramidal environment of π-coordinated copper(I) atom is formed by a lengthened to 1.376(2) A C=C bond of allyl group and by three chlorine atoms. Other two copper atoms are tetrahedrally surrounded by chlorine atoms only. The coordination polyhedra are combined into an original infinite (Cu4Cl62—)n fragment. Structural comparison of 1 and the recently studied copper(I) chloride π-complexes with 3-amino-, 2-amino-, 4-amino-1-allylpyridinium chlorides of respective [LCu2Cl3] (2), [L2Cu2Cl4] (3), and [LCuCl2] (4) compositions allowed us to reveal the trend of the inorganic fragment complication which depends on pKa (base) value of the corresponding initial heterocycle.

Single crystals of [C7H5N2H(C3H5)]+[Cu3Cl4]− were obtained for the first time by ac electrochemical synthesis from 1-allylbenzimidazolium and copper(II) chlorides in ethanol and structurally characterized. The unit cell parameters are a=8.6755(9) A, b=8.846(1) A, c=10.4540(7) A, α=85.36(1)°, β=70.529(7)°, γ=83.29(1)° , V=750.5(3) A3, space group P\(\bar 1\), R(F)=0.0551. In the π-complex, the copper and chlorine atoms form complicated infinite chains along the x axis. The 1-allylbenzimidazolium cation functions as an original bridge: it is coordinated by the Cu atom of one cuprous-chloride chain through the C=C bond of the allyl group and forms a N-H⋅⋅⋅Cl hydrogen bond with another inorganic chain through the N atom of the imidazole ring. The trigonal pyramidal environment of the Cu(1) atom includes three Cl atoms and the C=C bond; the environments of the Cu(2), Cu(3), and Cu(3a) are composed only of chlorine atoms. The positions of the Cu(2) and Cu(3a) atoms are partially disordered, which is manifested by the high thermal parameters for the Cu(2) atom and by the splitting of another copper atom into two equally occupied positions Cu(3) and Cu(3a).

Single crystals of [CuCl0.85Br0.15(C6H4N3CH2=CH2)] (I) were obtained by alternating current electrochemical synthesis; their X-ray structural investigation has been carried out (DARCh automatic diffractometer, MoKα radiation, θ/2θ scanning; 1460 reflections with F ≥ 4σ(F), R = 0.0517). The crystals are monoclinic, their space group is P21/c, a = 7.292(3) A, b = 17.947(8) A, c = 7.398(4) A, β = 93.56(4)°, V = 966(1) A3, Z = 4). Complex I is close in structure to the previously investigated compound [CuCl(C6H4N3CH2=CH2)] (II). In both structures, the trigonal-pyramidal surroundings of the copper atom include two halide atoms (one is apical), a nitrogen atom, and a C=C group. The Cu2X2 dimers are associated into {[Cu2X2(C6H5N3CH2=CH2)]}n layers due to the bridging function of the 1-allylbenzotriazole molecule. In spite of the similar coordination polyhedra of the metal atoms and identical bridging function of the ligand molecule in I and II, the differences in the conformation parameters of the allyl group π-coordinated by the copper(I) atom (trans-like in I and cis-like in II) caused by the presence of bromine atoms in the coordination sphere predetermine different structures of the organometallic [Cu2X2(C6H5N3CH2=CH2)]4 tetramer subunits in the layers and, as a consequence, formation of different crystal structures.