Hexakis(dimethylformamide)bis(hexaphenylcyclohexasiloxanehexaolato)hexacopper(II) Dimethylformamide Solvate

The sandwich-like title complex, hexakis(dimethylformamide)-1O,2O,3O,4O,5O,6O-bis[2,4,6,8,10,12-hexaphenylsiloxane-2,4,6,8,10,12-hexaolato(6-)-1:22O1,2:32O2,3:42O3,- 4:52O4,5:62O5,1:62O6]hexacopper(II) tetrakis(dimethylformamide) solvate, [Cu6(C3H7NO)6{(C6H5)6O12Si6}2].4C3H7NO, is comprised of two regular crown-shaped macrocyclic hexadentate organosiloxanolate ligands chelating a flat Cu6 hexagon, as in the ethanol-solvated analogue investigated previously. The title complex has a more distorted shape than the trigonal ethanol-solvated analogue, being slightly side-oblated, but still contains a large empty inner channel accessible by small molecules (the diameter of the free cross-section being about 2.5 Å). Each CuII ion has square-pyramidal coordination with four basal siloxanolate O atoms and an apical dimethylformamide (DMFA) molecule (coordinated through its carbonyl group). The average bond lengths are: Cu-O(Si) 1.964 (11) Å and Cu-O(DMFA) 2.215 (10) Å. The structure contains four additional DMFA molecules per complex unit, linked by weak C-HO hydrogen bonds. Unexpectedly, the C=O bond length is longer [1.248 (10) and 1.255 (9) Å] in the uncoordinated DMFA molecules than in the coordinated [1.214-1.227 (7) Å]

Synthesis and Characterization of Large Stereoregular Organosiloxane Cycles

The large stereoregular phenyltrimethylsiloxysiloxane macrocycles of general formula [PhSi(OSiMe3)O]n (n=6 and 12) have been selectively obtained with high yields by trimethylsilylation of cage-like oligophenylmetallasiloxanes (OPMS) which we described earlier. The compounds 3 (n=6) and 4 (n=12) have been characterized by NMR-spectroscopy method and by single crystal X-ray analysis. This investigation showed unambiguously that the siloxane macrocycles keep their size and configuration (the same as in the initial OPMS) during the trimethylsilylation. Thus a synthetic route for obtaining large stereoregular siloxane macrocycles has been developed

The Structure of a Potassium-Copper Complex with Six-Membered Macrocyclic Ethylsiloxanolate Ligands

The structure of K2{[EtSiO2]6K2Cu4[O2SiEt]6} · 4n-BuOH, a novel mixed sandwich-like complex of K+ and Cu2+ with two 6-membered macrocyclic ethylsiloxanolate ligands, was established by means of X-ray study. The ligands have an all-cis configuration and a crown conformation. Four Cu2+and two K+ ions form a planar hexagon sandwiched between antiparallel coaxial macrocyclic ligands. The K+ ions occupy two opposite apices of the hexagon. The Cu2+ ions have square-planar coordination with four siloxanolate OM atoms, while the K+ ions, are coordinated with two O atoms of the solvating butanol molecules, in addition to four OM atoms. The electric neutrality of the whole complex is due to the two outer-sphere K+ counter-ions, each located over one of the two siloxanolate macrocycles, i.e., over the «decks» of the sandwich and coordinated with endocyclic siloxane OSi atoms, as in crown-ether complexes

Novel Class of Transition Metal Coordination Compounds with Macrocyclic Organosiloxanolate Ligands; their Synthesis and Crystal Structure

Interaction of sodium organosiloxanolates with transition metal chlorides leads to the formation of a novel class of coordination compounds, polymetallaorganosiloxanolates (PMOS) {SiPh(O)-O}n−n M12 role= presentation \u3en−x2+Nan (M = Mn, Co, Ni, Cu), whose structure is elucidated by an X-ray diffraction study

Crystal Structure of the La\u3csup\u3e3+\u3c/sup\u3e Sandwich Complex Based on 8-membered Macrocyclic Siloxanolate Ligands

The product of the reaction between anhydrous lanthanum trichloride and potassium vinylsiloxanolate, K5[VinSiO2]8La4(μ4-OH)[O2SiVin]8 · 5n-BuOH·2H2O has been studied by X-ray diffraction. The compound is a «sandwich»-type complex where macrocyclic vinyloctasiloxanolate ligands with regularcis-configuration have co-axial and antiparallel orientation. These ligands coordinate a planar «cationic layer» formed by four La3+ ions and stabilized by an additional μ4-OH− bridge ligand. A three-dimensional cage structure of complex lanthansiloxanolate pentaanions linked through the coordinated K+ counter-ions is formed in the crystal studied

Crystal Structure of the Nd, Gd, and Dy Sandwich Complexes Involving 8-Membered Macrocyclic Phenylsiloxanolate Ligands

An X-ray structural investigation of the interaction products of anhydrous trivalent neodymium, gadolynium, and dysprosium chlorides with sodium phenylsiloxanolate was carried out. The synthesized compounds with the general formula Na6[PhSiO2]8M4(μ4-O)[O2SiPh]8 · 10EtOH · 8H2O (M = Nd, Gd, Dy) were found to be isomorphous isostructural sandwich complexes. The macrocyclic octaphenyloctasiloxanolate ligands in the complexes have anall-cis-configuration and are arranged in co-axial antiparallel pairs and coordinate the square planar groups of the four Nd3+, Gd3+, or Dy3+ ions stabilized by an additional central μ4-bridging O2− ligand. Six Na+ counterions form the outer coordination sphere of the complexes such that four of them coordinate the siloxane macrocycle O atoms in pairs in analogy with crown-ether complexes

Bimetallic siloxane cluster of higher valent transition metals: Na{[η\u3csup\u3e6\u3c/sup\u3e-cyclo-(PhSiO\u3csub\u3e2\u3c/sub\u3e)\u3csub\u3e6\u3c/sub\u3e]\u3csub\u3e2\u3c/sub\u3eCo\u3csub\u3e2\u3c/sub\u3eNi\u3csub\u3e4\u3c/sub\u3e(μ\u3csub\u3e6\u3c/sub\u3e-Cl)}

The bimetallic siloxane cluster / cage compound Na{[η6-cyclo-(PhSiO2)6]2Co2Ni4(μ6-Cl)} was preparred and characterized by single crystal X-ray diffraction, spectroscopic, magnetic and electrochemical methods

Cyclosiloxane Sandwich Complexes of a Lanthanide Metal: Na\u3csub\u3e6\u3c/sub\u3e{[(C\u3csub\u3e6\u3c/sub\u3eH\u3csub\u3e5\u3c/sub\u3eSiO\u3csub\u3e2\u3c/sub\u3e)\u3csub\u3e8\u3c/sub\u3e]\u3csub\u3e2\u3c/sub\u3eNd\u3csub\u3e4\u3c/sub\u3e(\u3cem\u3eμ\u3c/em\u3e\u3csub\u3e4\u3c/sub\u3e-O)}

The oligocyclosiloxane cluster (‘sandwich’) complex of Nd3+, Na6{[(C6H5SiO2)8]2Nd4(μ4-O)} has been prepared and characterized by analyses, infrared spectra, single crystal X-ray diffraction, magnetic susceptibility, conductivity and cyclic voltammetry. The μ4-O2− anion is in a square planar coordination environment. Electrochemical studies identify the cluster core as a moiety with a delocalized electron system

Cyclooligosiloxanolate Cluster Complexes of Transition Metals and Lanthanides

Cyclooligosiloxanolate complexes of higher valent transition metals and lanthanides were synthesized and characterized by single-crystal X-ray diffraction experiments, spectra, cyclic voltammetry, conductivity and magnetic behaviour. These complexes are sandwich-type clusters containing assemblies of 4 to 8 metals between siloxanolate ligand ‘layers’. A high degree of electron delocalization in the metal containing fragment of these complexes is detected by electrochemical and magnetic measurements. The synthesis, crystal and molecular structure determined by X-ray diffraction of Na6{[C6H5SiO2)8]2Gd4(μ4-O)} is reported