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]

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

A Versatile Equilibrium Method for the Synthesis of High-Strength, Ladder-like Polyphenylsilsesquioxanes with Finely Tunable Molecular Parameters

A versatile equilibrium method for synthesizing ladder-like polyphenylsilsesquioxanes (L-PPSQs) with various molecular weights (from 4 to 500 kDa) in liquid ammonia was developed. The effect of diverse parameters, such as temperature, monomer concentration, reaction time, addition or removal of water from the reaction medium, on the polycondensation process was determined. The molecular weight characteristics and structure of the L-PPSQ elements obtained were determined by GPC, 1H, 29Si NMR, IR spectroscopy, viscometry, and PXRD methods. The physicochemical properties of L-PPSQs were determined by TGA and mechanical analyses