Maxim N. Sokolov

A Novel Framework Type for Inorganic Clusters with Cyanide Ligands: Crystal Structures of Cs2Mn3[Re6Se8(CN)6]2⋅15 H2O and (H3O)2Co3[Re6Se8(CN)6]2⋅14.5 H2O

Large cavities occupied by cations and water molecules are part of the polymeric inorganic cluster structure made up of [Re6Se8(CN)6]4− and M2+ ions (M=Mn, Co; see structure on the right). Remarkably, the water molecules play an essential role in the stabilization of the structure: When the cluster is heated to 80–160°C, water is lost irreversibly, and a sharp change in structure is observed.

Mono- and polynuclear aqua complexes and cucurbit[6]uril: Versatile building blocks for supramolecular chemistry

The review surveys new data on the directed construction of supramolecular organic–inorganic compounds from macrocyclic cavitand cucurbit[6]uril (C36H36N24O12)and mono- and polynuclear aqua complexes. Due to the presence of polarized carbonyl groups, cucurbit[6]uril forms strong complexes with alkali, alkaline earth and rare-earth metal ions, and hydrogen-bonded supramolecular adducts with cluster and polynuclear aqua complexes of transitional metals. A wide variety of supramolecular compounds and their unique structures are described.

Triangular thiocomplexes of molybdenum : reactions with halogens, hydrohalogen acids and phosphines

Abstract The triangular (NH4)2Mo3S13·2H2O complex interacts with Cl2 and Br2 in CH3CN and with concentrated hydrohalogen acids HX (X = Cl, Br and I) retaining its Mo3(μ3-S)(μ-S2)34+ cluster fragment to produce the Mo3(μ3-S)(μ2-S2)3X62− complexes in high yields. IR and Raman spectra of the Mo3S7X62− complexes have been studied. Salts of Mo3S7X62− (X = Cl, Br) containing 92Mo, 100Mo and 34S isotopes and compounds with μ2-(32S-34S) ligands have been also synthesized. For Mo3S7Cl62−, an analysis of the normal vibrations has been performed. The Mo3S7X62− complexes (X = Cl, Br) interact with phosphines (PPh3 and dppe). The reactions proceed with elimination of the μ2-S2 sulfurs to form sulfides of the phosphines and the phosphine complexes Mo3S4X4·3PPh3 and Mo3S4X4·3dppe containing a Mo3S44+ cluster fragment. It has been shown, for the reaction of Mo3(μ3-34S)(μ2-32Se-34Sa)3Cl62− with PPh3, that it is the equatorial μ2-S2 sulfurs that are predominantly eliminated.

Cucurbituril as a New Macrocyclic Ligand for Complexation of Lanthanide Cations in Aqueous Solutions

(Aqua)lanthanide complexes with cucurbituril {[Gd(NO3)(H2O)4](C36H36N24O12)}(NO3)2·7H2O (1), {[Gd(NO3)(C2H5OH)(H2O)3](C36H36N24O12)}(NO3)2·5.5H2O (2), {[Ho(NO3)(H2O)4](C36H36N24O12)}(NO3)2·7H2O (3), {[Yb(NO3)(H2O)4](C36H36N24O12)}(NO3)2·6H2O (4), {[La(H2O)6(SO4)](C36H36N24O12)}(NO3)·12H2O (5), {[Gd(H2O)4]2(C36H36N24O12)3}Br6·45H2O (6), and {[Ce(H2O)5]2(C36H36N24O12)2}Br6·26H2O (7) were obtained in high yield by reaction of cucurbituril with aqueous solutions of lanthanide(III) species. The crystal structures of the compounds show a packing of 1:1, 2:2, and 2:3 in the (cucurbituril)lanthanide complexes in which cucurbituril plays a bidentate ligand role, and water molecules of the (aqua)lanthanide complexes form hydrogen bonds with carbonyl groups of the cucurbituril molecule. The guest water molecule is situated in the cucurbituril molecule cavity of 2 and 5. The crystal structure of 6 is a packing of three-deck sandwiches, built from alternating cucurbituril molecules and Gd(H2O)43+ ions. The largest distance between outermost oxygen atoms in the sandwiches is 30.04 A. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

Supramolecular compounds of cucurbituril with molybdenum and tungsten chalcogenide cluster aqua complexes

The review surveys the synthesis and structures of a new class of supramolecular compounds composed of the macrocyclic cavitand cucurbituril and molybdenum or tungsten chalcogenide clusters. The structural motifs of supramolecular compounds and factors influencing their formation are considered.

Triangular W3S74+ and W3S44+ complexes

Abstract Methods for the synthesis of triangular thiohalogenide complexes of tungsten W 3 S 7 X 4 (XCl, Br) proceeding from metallic tungsten or WS 3 have been developed. Ways have been found for converting these polymeric complexes to triangular W 3 S 7 X 6 2− complexes which preserve the architecture of the W 3 (μ 3 -S)(μ 2 -S 2 ) 3 4+ cluster fragment. Heating W 3 S 7 X 4 in a PPh 4 X melt or in concentrated acids HX in the presence of Et 4 NX afforded PPh 4+ and Et 4 N + salts of W 3 S 7 X 6 2− (XCl, Br). The structure of (Ph 4 P) 2 W 3 S 7 Br 6 ( III ) was established by X-ray diffraction analysis. The crystals of III are orthorhombic, a =18.082(2), b =25.834(3), c =27.370(2) A, Z =8, Pbca , R ( R w )=0.049 (0.055). The Et 4 N + salt of W 3 34 S 7 Br 6 2− has been obtained and a calculation of the normal vibrations has been performed for W 3 S 7 Br 6 2− . Interaction of W 3 S 7 Br 4 , with a KNCS melt or an aqueous solution of (NH 4 ) 2 S x involves transformation of the cluster fragment W 3 S 7 4+ to a W 3 S 4 4+ fragment to produce W 3 S 4 (NCS) 9 5− and W 3 S 4 (S 4 ) 3 (NH 3 ) 3 2− complexes. The structure of (NH 4 )(H)(H 2 O) 3 W 3 S 16 (NH 3 ) 3 ( VI ) was established by X-ray diffraction analysis. The crystals of VI are trigonal, a =12.508(1), c =10.112(1) A, Z =2, P 31 c , R ( R w )=0.029 (0.033).

Triangular M3Se74+ and M3Se44+ complexes (M = Mo, W). An X-ray study of Mo3Se7(Et2NCS2)4 and W3Se7(Et2NCS2)4

Abstract New methods for the synthesis of triangular M 3 Se 7 4+ and M 3 Se 4 4+ complexes soluble in organic solvents have been developed which proceed from polymeric M 3 Se 7 X 4 (M = Mo, W; X = Cl, Br). Heating of Mo 3 Se 7 Cl 4 in a PPh 4 Cl melt has produced the (PPh 4 ) 2 Mo 3 Se 7 Cl 6 salt. Selenobromide complexes of molybdenum and tungsten are less stable and have been converted to M 3 Se 7 (dtc) 4 complexes by reacting them with NaS 2 NCEt 2 ·3H 2 O (Nadtc·3H 2 O) in CH 3 CN. The structure of M 3 Se 7 (dtc) 4 (M = Mo, W) has been determined by X-ray structural analysis: a = 16.728(5), b =18.604(7), c =13.324(3) A, β=99.12(3)°, Z =4, P 2 1 / c , R F =0.1344 for W 3 Se 7 (dtc) 4 ; a =16.652(5), b =18.614(8), c =13.337(3) A, β=99.11(2)°, Z =4, P 2 1 / c , R F =0.0628 for Mo 3 Se 7 (dtc) 4 . Heating of M 3 Se 7 X 4 in a melt of 1,10- phenanthroline (phen) produces salts containing M 3 Se 7 (phen) 3 4+ with different anions (Cl − , Br − , ZnCl 4 2− , ZnBr 4 2− ). The action of phosphines on M 3 Se 7 4+ complexes gave M 3 Se 7 4+ complexes Mo 3 Se 4 (dtc) 4 (PPh 3 ) and Mo 3 Se 4 (dppe) 3 Cl 4 (dppe is Ph 2 PCH 2 CH 2 PPh 2 ).

Mechanochemical synthesis of soluble complexes containing M3S74+ and M3Se74+ fragments from polymeric M3Y7Br4 (M Mo, W; Y S, Se). The crystal structure of (PPN)2W3S7Cl6

Abstract The interaction of solid W3S7Br4 or W3Se7Br4 with Et4NBr under vibrational mill conditions followed by extraction with acetonitrile resulted in the isolation of (Et4N)2W3S7Br6 (1) and (Et4N)2W3Se7Br6 (2) salts. Treatment of the product of the analogous reaction of Mo3Se7Br4 and Et4NBr with sodium diethyldithiocarbamate (Nadtc) resulted in [Mo3Se7(dtc)3]dtc (4). The M3Y74+ (Y = S, Se) cluster fragments are retained in all of these reactions. By dissolving 1 in conc. hydrochloric acid and adding PPNCl, the (PPN)2W3S7Cl6 salt (5) was obtained, for which an X-ray study has been performed. Selected distances for the cluster anion W3(μ3-S)(μ2-S2)3Cl62− are 2.7270(7)-2.7445(6) A for WW, 2.360(3)-2.361(3) A for W—(μ3,-S), 2.032(4)–2.052(4) A for SS, 2.429(3)- 2.459(2) and 2.493(4)–2.519(3) A for WCl (for cis and trans positions with respect to μ3-S, respectively). Rather short distances (3.17–3.21 A) between the chlorine atoms and sulphur atoms of the μ2-S2 ligands of the adjacent anions were noted. The interaction of 2 with 1,2-bisdiphenylphosphine ethane (dppe) is accompanied by elimination of selenium to produce W3Se4Br3(dppe)3]Br (6).

Alkynyl Complexes of High-Valence Clusters. Synthesis and Luminescence Properties of [Mo6I8(C≡CC(O)OMe)6]2–, the First Complex with Exclusively Organometallic Outer Ligands in the Family of Octahedral {M6X8} Clusters

The reaction of [Mo6I14](2-) with methyl propiolate HC≡CC(O)OMe in the presence of Ag(+) and Et3N yielded the new luminescent complex [Mo6I8(C≡CC(O)OMe)6](2-), the first fully organometallic complex in the family of octahedral {M6X8} clusters. The cluster was crystallized as tetraphenylphosphonium salt and characterized by X-ray single-crystal diffraction and elemental analyses, mass spectrometry, (13)C NMR, UV-vis, and luminescence spectroscopies.

Synthesis, structure, vibrational spectra and chemical properties of the triangular molybdenum and tungsten complexes M3(μ3-S)(μ2-SSe)3X62− (M = Mo, W; X = Cl, Br)

Abstract Salts containing M3(μ3-S)(μ2-S2)3X62− (M = Mo, W; X = Cl, Br) anions interact with SePPh3 upon heating in acetonitrile to form SPPh3 and M3(μ3-S)(μ2-SSe)3X62−. The stereochemisty of this reaction has been studied. In the reaction of SePPh3 with Mo3(μ3-34S)(μ2-34Sa32Se)3X62− replacement of the equatorial sulfur atoms takes place, and 32SPPh3 and Mo3(μ3-34S)(μ2-34SaSee)3X62− are produced. The structure of (PPh3Et)2Mo3(μ3-S)(μ2-SSe)3Cl6 (I) was established by X-ray diffraction analysis. The crystals of I are triclinic, space group P 1 (a = 13.547(2), b = 13.755(2), c = 15.736(3) A; α = 101.79(1), β = 97.71(1), γ = 110.49(1)°, Z = 2). A total of 5721 independent reflections has been collected on an automated diffractometer, and the structure was solved to R = 0.051 (Rw = 0.062). The selenium atoms are essentially in the plane of the Mo3 triangle. The SSe distances are 2.157(5)–2.163(4) A. Complex I is the first compound containing a SSe ligand that has been structurally characterized. IR and Raman spectra of M3S4Se3X62− have been studied. For Mo3S4Se3Cl62− an analysis of the normal vibrations has been performed. The force constant of the SSe bond in complex I is 2.3 mdyn/ A. Heating of (Et4N)2Mo3S4Se3Br6 under vacuum at 450 °C gave rise to MoSSe.