Eduard B. Rusanov

Pentakis(trifluoromethyl)phenyl, a sterically crowded and electron-withdrawing group: synthesis and acidity of pentakis(trifluoromethyl)benzene, -toluene, -phenol, and -aniline.

A general route to functionalized pentakis(trifluoromethyl)phenyl (C6(CF3)5) derivatives, promising building blocks for designing novel stable carbenes, radical species, superacids, weakly coordinating anions and other practically and theoretically useful species, is presented. This pertrifluoromethylation route proceeds via conveniently pregenerated (trifluoromethyl)copper (CF3Cu) species in DMF, stabilized by addition of 1,3-dimethyl-2-imidazolidinone (DMI). These species react with hexaiodobenzene at ambient temperature to give the potassium pentakis(trifluoromethyl)phenoxide along with hexakis(trifluoromethyl)benzene and pentakis(trifluoromethyl)benzene in a combined yield of 80%. A possible reaction pathway explaining the formation of pentakis(trifluoromethyl)phenoxide is proposed. Pentakis(trifluoromethyl)phenol gives rise to easily functionalized pentakis(trifluoromethyl)chlorobenzene and pentakis(trifluoromethyl)aniline. Pertrifluoromethylation of pentaiodochlorobenzene and pentaiodotoluene allows straightforward access to pentakis(trifluoromethyl)chlorobenzene and pentakis(trifluoromethyl)toluene, respectively. XRD structures of several C6(CF3)5 derivatives were determined and compared with the calculated structures. Due to the steric crowding the aromatic rings in all C6(CF3)5 derivatives are significantly distorted. The gas-phase acidities (Delta Gacid) and pKa values in different solvents (acetonitrile (AN), DMSO, water) for the title compounds and a number of related compounds have been measured. The origin of the acidifying effect of the C6(CF3)5 group has been explored using the isodesmic reactions approach.

New tri- and tetranuclear transition metal spin clusters incorporating a versatile polydentate Schiff base ligand

Abstract A trinuclear Fe(III) complex [Fe3(OAc)3L3] (1), a tetranuclear Mn(III) complex [Mn4Cl4L4] (2) and a tetranuclear Ni(II) complex [Ni4(MeOH)4L4] (3) have been synthesized from the reaction of simple metal salts with ligands derived from salicylidene-2-ethanolamine (H2L). Structural characterization of the three complexes reveals distinctly different topologies, despite the similar coordination modes of the ligand L2−. Preliminary magnetochemical studies have been performed and reveal spin ground states of S=1/2,8 and 4 for complexes 1, 2 and 3, respectively.

1,2,4-Triazolyl-Carboxylate-Based MOFs Incorporating Triangular Cu(II)-Hydroxo Clusters: Topological Metamorphosis and Magnetism

Bifunctional 1,2,4-triazole-carboxylate ligands, an achiral 1,2,4-triazol-4-yl-acetic acid (trgly-H) and a chiral (d)-2-(1,2,4-triazol-4-yl)-propionic acid (d-trala-H), derived from the corresponding α-amino acid precursors revealed unique binding abilities in the construction of Cu(II)-coordination polymers composing discrete triangular [Cu3(μ3-OH)] clusters. A related series of MOFs, [Cu3(μ3-OH)(trgly)3(SO4)]·2H2O (1a), [Cu3(μ3-OH)(trgly)3(H2O)3]SO4·16H2O (1b), Cu3(μ3-OH)(d-trala)3(ClO4)0.5](ClO4)1.5·1.5H2O (2), was prepared, and their crystal structures were determined by means of X-ray diffraction. Being singly deprotonated, the organic ligands act as multidentate μ3- or μ4-donors using tr and -COO(-) moieties. The generated [Cu3(μ3-OH)(tr)3] cluster core is primarily supported by three [-N-N-] triazole heterocycles in a basal plane and tripodal-assisted μ3-anions (SO4(2-): 1a; ClO4(-): 2) capping the axial faces. The carboxylate groups join the units into either two-dimensional (2D) layer (1a, 2) or 3D zeolite-like networks (1b). Compound 1b represents the topology of α-Po (pcu: 4(12).6(3)) and crystallizes in the noncentrosymmetric space group I4̅3m, in which the six-connected [Cu3(μ3-OH)] clusters and trgly self-assemble in an open-channel cubic array possessing ∼56% solvent-accessible volume. Upon slight thermal treatment (∼60 °C), the structure irreversibly shrinks to the nonporous 2D motif 1a that belongs to a uninodal (3,6) network type. In structure 2 (space group R32), due to the [-N-N-] triazole and 1,3-bidentate carboxylate binding mode, each organic ligand bridges three metal clusters affording cross-linking of two adjacent layers with the same (3,6) topology. The resultant 3,9-c net is novel and can be categorized as two-nodal with point symbol {4(18).6(18)}{4(2).6}3. Spin frustration and antisymmetric exchange effects, resulting in abnormally low g values in the S = 1/2 states, were observed in the magnetic properties and the EPR spectra.

Ag(I)/V(V) heterobimetallic frameworks generated from novel-type {Ag2(VO2F2)2(triazole)4} secondary building blocks: a new aspect in the design of SVOF hybrids.

A series of new silver(I)-containing MOFs [Ag(2)(tr(2)ad)(2)](ClO(4))(2) (1), [Ag(2)(VO(2)F(2))(2)(tr(2)ad)(2)]·H(2)O (2), [Ag(2)(VO(2)F(2))(2)(tr(2)eth)(2)(H(2)O)(2)] (3), and [Ag(2)(VO(2)F(2))(2)(tr(2)cy)(2)]·4H(2)O (4) supported by 4-substituted bifunctional 1,2,4-triazole ligands (tr(2)ad = 1,3-bis(1,2,4-triazol-4-yl)adamantane, tr(2)eth = 1,2-bis(1,2,4-triazol-4-yl)ethane, tr(2)cy = trans-1,4-bis(1,2,4-triazol-4-yl)cyclohexane) were hydrothermally synthesized and structurally characterized. In these complexes, the triazole heterocycle as an N(1),N(2)-bridge links either two adjacent Ag-Ag or Ag-V centers at short distances forming polynuclear clusters. The crystal structure of compound 1 is based on cationic {Ag(2)(tr)(4)}(2+) fragments connected in a 2D rhombohedral grid network with (4,4) topology. The neighboring layers are tightly packed into a 3D array by means of argentophilic interactions (Ag···Ag 3.28 Å). Bridging between different metal atoms through the triazole groups assists formation of heterobimetallic Ag(I)/V(V) secondary building blocks in a linear V-Ag-Ag-V sequence that is observed in complexes 2-4. These unprecedented tetranuclear {Ag(2)(VO(2)F(2))(2)(tr)(4)} units (the intermetal Ag-Ag and Ag-V distances are 4.24-4.36 and 3.74-3.81 Å, respectively), in which vanadium(V) oxofluoride units possess distorted trigonal bipyramidal environment {VO(2)F(2)N}¯, are incorporated into 1D ribbon (2) or 2D square nets (3, 4) using bitopic μ(4)-triazole ligands. The valence bond calculation for vanadium atoms shows +V oxidation state in the corresponding compounds. Thermal stability and photoluminescence properties were studied for all reported coordination polymers.

New microporous copper(II) coordination polymers based upon bifunctional 1,2,4-triazole/tetrazolate bridges

A series of Cu(II) coordination polymers, [Cu(μ2-L1)3]PO3F (1), [Cu2(μ2-L1)4(μ4-L1)](NO3)4·2H2O (2), [Cu(μ2-L1)2(μ2-X)]X·12H2O (X = Cl, 3; Br, 4), [Cu4(μ2-OH)2(μ4-L1)3(μ2-L1)2(H2O)2](CF3SO3)6·10H2O (5), [Cu3(μ2-OH)2(μ4-L1)(H2O)2(μ3-SO4)2] (6), [Cu(μ4-L1)(μ2-SO4)]·6H2O (7), [Cu2(μ4-L2)3]Cl·12H2O (8) involving new bifunctional p-phenylene bridged bi(1,2,4-triazole) and mixed 1,2,4-triazole-tetrazolate based ligands (L1= 1,4-phenylene-4,4′-bi(1,2,4-triazole), HL2= 5-(4-[1,2,4]triazol-4-yl-phenyl)-1H-tetrazole) has been prepared under hydrothermal conditions and their structures have been established by means of X-ray diffraction. In crystal structures 1–8, the organic ligands, utilizing two neighboring nitrogen atoms (N1, N2 in triazole (trz) and N2, N3 in tetrazolate), behave either in μ2 or in μ2 + μ4 manner binding the adjacent metal centers or Cu3(μ2-OH)2 clusters into 1D columns (1, 3, 4), 2D zigzag layers (2) and 3D frameworks (5–8). The mutual coplanarity between uncoordinated trz moiety and p-phenylene spacer as well as its radial disposition around the “propeller-like” [Cu2(η2-trz)3] subunits is a crucial factor, which specifically mediates multiple π–π interactions through intercalation of the neighboring Cu(η2-trz)n (n = 2,3) axles, and as a consequence, affording one-dimensional channels with trigonal (1, 2) or rhombic geometry (3, 4). Large rectangular channels have been realized in neutral [Cu(μ4-L1)(μ2-SO4)]n (7) and cationic [Cu2(μ4-L2)3]nn+ (8) frameworks, in which the remaining void space is filled by water molecules and counter anions (Cl−).

One- and two-dimensional coordination polymers of 3,3′,5,5′-tetramethyl-4,4′-bipyrazolyl, a new perspective crystal engineering module

Abstract The coordination polymers based upon new bidentate ligand 3,3′,5,5′-tetramethyl-4,4′-bipyrazolyl (4,4′-bpz) have been prepared and characterized by means of X-ray analysis. In all compounds Ag(4,4′-bpz)NO3·CH3OH (1), Cd(4,4′-bpz)(C3H7OH)(NO3)2 (2), Cd(4,4′-bpz)2(NO3)2 (3), Cu(4,4′-bpz)2(H2O)(BF4)2·0.5C6H5Br (4), and Cu(4,4′-bpz)2(H2O)(HCOO)2·2.5HCONH2 (5) the molecules of bipyrazolyl act as bridging neutral groups and connect two metal atoms at the distances of 9.58–10.25 A. Complexes 1 and 2 exhibit one-dimensional polymeric structure, while compounds 3–5 exist as two-dimensional polymers, containing layers of four-connected coordination nets. In structures 4 and 5 the layers are interlinked by means of hydrogen bonding involving counter anions, which lead to formation of three-dimensional open networks capable of incorporation of hydrophilic (5) or hydrophobic (4) guest molecules. Geometry of coordination polymer in these cases is significantly dominated by the angular structure of 4,4′-bpz ligand, while structure of the coordination net in 3 is very similar for analogues containing linear 4,4′-bipyridine bridges.

Novel unsymmetrically functionalized BEDT–TTF derivatives: synthesis, crystal structure and electrochemical characterization

Novel functionalized bis(ethylenedithio)tetrathiafulvalene (BEDT–TTF) derivatives 4 and 5 have been synthesized in good yields from cyano precursor via a cross-coupling reaction. Their redox potentials have been studied by cyclic voltammetry in a dichloromethane solution; this indicated that they are slightly weaker electron donors than BEDT–TTF. Compound 4 has been studied by X–ray crystallography; this revealed that, in the crystal, the molecules were held together by some unconventional C–H···N and C–H···S hydrogen bonds.

Functionalized adamantane tectons used in the design of mixed-ligand copper(II) 1,2,4-triazolyl/carboxylate metal-organic frameworks.

Bistriazoles, 1,3-bis(1,2,4-triazol-4-yl)propane (tr(2)pr) and 1,3-bis(1,2,4-triazol-4-yl)adamantane (tr(2)ad), were examined in combination with the rigid tetratopic 1,3,5,7-adamantanetetracarboxylic acid (H(4)-adtc) platform for the construction of neutral heteroleptic copper(II) metal-organic frameworks. Two coordination polymers, [{Cu(4)(OH)(2)(H(2)O)(2)}{Cu(4)(OH)(2)}(tr(2)pr)(2)(H-adtc)(4)]·2H(2)O (1) and [Cu(4)(OH)(2)(tr(2)ad)(2)(H-adtc)(2)(H(2)O)(2)]·3H(2)O (2), were synthesized and structurally characterized. In complexes 1 and 2, the N(1),N(2)-1,2,4-triazolyl (tr) and μ(3)-OH(-) groups serve as complementary bridges between adjacent metal centers supporting the tetranuclear dihydroxo clusters. The structure of 1 represents a unique association of two different kinds of centrosymmetrical {Cu(4)(OH)(2)} units in a tight 3D framework, while in compound 2, another configuration type of acentric tetranuclear metal clusters is organized in a layered 3,6-hexagonal motif. In both cases, the {Cu(4)(OH)(2)} secondary building block and trideprotonated carboxylate H-adtc(3-) can be viewed as covalently bound six- and three-connected nodes that define the net topology. The tr ligands, showing μ(3)- or μ(4)-binding patterns, introduce additional integrating links between the neighboring {Cu(4)(OH)(2)} fragments. A variable-temperature magnetic susceptibility study of 2 demonstrates strong antiferromagnetic intracluster coupling (J(1) = -109 cm(-1) and J(2) = -21 cm(-1)), which combines for the bulk phase with a weak antiferromagnetic intercluster interaction (zj = -2.5 cm(-1)).

Cooperative association of pyrazoles and phenols: A versatile binary system

The ability of self-complementary H-bond donor/acceptor phenol (OH/O) and pyrazole (NH/N) molecules for cooperative association allowed the developing of a range of binary compounds, in which the molecular counterparts are integrated by hydrogen bonding. Complexes involving either monofunctional 3,5-dimethylpyrazole and phenol and polyfunctional 3,3′,5,5′-tetramethyl-4,4′-bipyrazole, hydroquinone and phloroglucinol are based on mixed phenol–pyrazole chains. They reveal common features allowing high level of control over the entire connectivity and dimensionality. Unprecedented NH⋯π pyrazole hydrogen bonding was essential for the structure of the resorcinol complex.

Synthesis and crystal structure of rubidium hydrogen oximate complexes with 18-crown-6: is it possible to reach a perfect fit of the rubidium atom inside the crown ether cavity?

Abstract Complexes of composition Rb(18-crown-6) {H(X)2} · nH2O (X = isonitrosocyanoacetamide, n = 3 (1) and isonitrosobenzoylacetonitrile, n = 0 (2) have been prepared and studied by means of X-ray diffraction (1: triclinic, space group P 1 , with a = 10.143(2), b = 11.912(2), c = 13.518(2) A ; α = 114.40 (1), β = 91.61(1), γ = 103.92(1)°, V = 1428.6(4) A 3 , Z = 2 ; final R1 = 0.032 based on 3660 independent reflections with 1 > 2σ (1); 2: monoclinic, space group P21/n, with a = 9.522(2), b = 16.469(3), c = 10.794(2) A ; β = 95.13(3)° , V = 1685.9(6) A 3 , Z = 2 ; final R1 = 0.038 based on 1547 independent reflections with I > 2σ (I). Both the structures consist of Rb(18-crown-6)+ cations and complex hydrogen oximate anions {H(X)2}, formed via strong hydrogen bonding between the oxygen atoms of nitroso groups (O···O ca. 2.455(6)–2.473(3) A). In 1 the rubidium atom is situated 1.012(1) A above the mean plane of macrocyclic oxygen atoms (RbO 2.921(2)–3.129(2) A) and adopts a typical ‘sunrise coordination’, while the structure of complex 2 demonstrates an unprecedented example of a perfect fit of the rubidium atom inside the crown ether cavity. Metal atom occupies a center of inversion and resides exactly in the center of the crown ether (RbO 2.822(5)–2.872(4) A).