V. A. Igonin

Novel class of transition metal coordination compounds with macrocyclic organosiloxanolate ligands; their synthesis and crystal structure

Abstract 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 M 1 2 n−x 2+ Na n (M = Mn, Co, Ni, Cu), whose structure is elucidated by an X-ray diffraction study.

An Unusual sandwich-type nickel oxide-siloxanolate complex {[PhSiO]}6 (μ4-O)2 (μ3-O)4[Ni8(μ3-0)2](μ3-O)4(μ4-O)2 [PhSiO]6}·14n-BuOH·10H2O·2Me2CO. Synthesis and crystal structure

Abstract An X-ray crystal study of the nickel oxide-siloxanolate complex {[PhSiO] 6 (μ 4 -O) 2 (μ 3 -O) 4 [Ni 8 (μ 3 O) 2 ] (μ 3 -O) 4 (μ 4 -O) 2 [PhSiO] 6 }·14n-BuOH·10H 2 O·2MeCO (I or Ia without noncoordinating solvate molecules) having a cage structure has been carried out. The complex studied was prepared by the interaction of NiCl 2 with the product of the reaction of phenylsilsesquioxane (PhSiO 1.5 ) n with NaOH. The polynuclear cage-like centrosymmetric molecule Ia has a sandwich-type structure. The inner two-dimensional nickel oxide fragment Ni 8 o 2 (μ-O) 12 2 = Ni 8 O 8 is structurally identical to a fragment of the NiO crystal layer which is one Ni atom thick and parallel to the (111) plane. All Ni atoms have oxygen atoms in an octahedral coordination (oxide, silanolate, molecules of water, butanol and acetone). The O atoms of the nickel oxide layer have both trigonal pyramidal (μ 3 -O) and distorted tetrahedral (μ 4 -O) coordination. The nickel oxide layer is bonded by NiOSi bridges through silanolate O atoms with two outer 12-membered hexasiloxane (SiO) 6 cycles (sandwich “caps”) with an almost ideal crown conformation. Some of the butanol and H 2 O crystallosolvate molecules do not coordinate the Ni atoms being included in the cavities between Ia molecules. The NiO bond lenghts are 2.006–2.159 A, while the average SiO(Si) and SiO(Ni) bond lengths are 1.637 and 1.618 A, respectively.

Synthesis and Characterization of Large Stereoregular Organosiloxane Cycles

The large stereoregular phenyltrimethylsiloxysiloxane macrocycles of general formula [PhSi(OSiMe 3 )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.

A novel route to the trisilacyclobutane moiety. A possible silene-disilene reaction

Abstract The reaction of (Me 3 Si) 3 SiC(O)Ad with a two-fold excess of Et 3 GeLi in THF, gives a 1:2 mixture of: 1,1,2,2-tetra-(trimethylsilyl) -3-trimethylsilyl-3-triethylgermoxy, 4-(1-adamantyl)-trisilacyclobutane ( 4 ) and adamantoyladamantyl-carbinol ( 5 ). The crystal structure of 4 is described and discussed. It is suggested that the trisilacyclobutane skeleton is formed by a cycloaddition reaction between a silene and a disilene.

Crystal structures of cycloheteropentasilanes (η5-Cp)2Ti(SiPh2)5 and O(SiPh2)5

Abstract An X-ray diffraction study of two heterocyclic polysilanes (η 5 -Cp) 2 Ti(SiPh 2 ) 5 and O(SiPh 2 ) 5 has been carried out. In the titanasilane cycle the relevant bond lengths and angles are as follows: Ti 2.755(7) and 2.765(8) A, SiSi 2.40–2.45(3) A, SiTiSi 99.1(2)°. TiSiSi and SiSiSi 114.4–118.3(3)°; the cycle has a chari conformation and torsion angles of 43–59°. the geometric parameters of the oxasilane cycle are: SiO 1.643 and 1.644(3) A, SiSi 2.369–2.388(2) A, SiOSi 145.7(2)°, OSiSi and SiSiSi 106.5–109.3(1)°; the cycle has a boat conformation.

Synthesis and crystal structure of two titanasilazanes

Abstract Interaction of TiCl4 and LiN(SiMe3)2 produces two titanasilazanes, whose structure is established by an X-ray study. In both structures, TiIV atoms are tetra-coordinated. Geometrical parameters of the centrosymmetrical molecule of the first compound are unexceptional. In the bicyclic frame of the second complex, the bond lengths are: TiN 1.866–2.034(3), SiN(sp3) 1.890(4) A.

Crystal structure of the La3+ 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.

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.

CRYSTAL STRUCTURE OF ORGANOSILICON COMPOUNDS. LXIV.* STRUCTURE OF FOUR UNSATURATED CYCLOCARBOSILANES

An x-ray structural investigation of four permethylcyclocarbosilanes, whose heterocycles are formed by −Si−CH2−CH2−, −Si−CH=CH−, and −Si−C≡C− fragments, has been carried out. Strong distortions of some bond lengths and bond angles (caused by the shortness of the Si...Si distances between the neighboring Si atoms and the absence of intermolecular contancts with the participation of atoms of the heterocycles), which attest to statistical disordering of the molecules in the crystals, whose character could be established unequivocally for three of the compounds, have been observed in all the structures.