Stabile Silantriole als Synthesebausteine für Titanasilasesquioxane - Modellverbindungen für titandotierte Zeolithe

Base-stabilized silaimine and its donor-free dimer derived from the reaction of NHC-supported silylene with SiCl4

Reaction of the N-heterocyclic carbene (NHC)-stabilized silylene ArN(SiMe₃)Si(IiPr)Cl (1, Ar = 2,6-iPr₂C₆H₃, IiPr = 1,3-diisopropyl-4,5-dimethyl-imidazol-2-ylidene) with SiCl₄ resulted in the formation of three different products ArNSi(IiPr)Cl₂ (2), ArN(SiMe₃)SiCl₃ (3) and (ArNSiCl₂)₂ (4) under different conditions.

Organosilicon platforms: bridging homogeneous, heterogeneous, and bioinspired catalysis

Organosilicon compounds form versatile structures such as cubic metallasiloxanes, cage-like silsesquioxanes, macromolecular nanocages, and flexible dendrimers and linear metallasiloxanes, and are useful as catalysts, ligands for metal complexes, and catalyst supports.

Trisilane-1,3-diolato Complexes of Ti and Zr: Syntheses and X-ray Crystal Structures

The syntheses and structures of zirconium and titanium complexes containing the novel chelating trisilane-1,3-diolate ligand [Me2Si(R2SiO)2]2- (R = SiMe3) (5)-H2 are reported. The chloride complexes [Me2Si(R2SiO)2]TiCl2 (7a) and [Me2Si(R2SiO)2]ZrCl2 x 2 THF (7b) were prepared by the reaction of MCl4 (M = Ti, Zr) with [Me2Si(R2SiO)2]2Ti (6a) and [Me2Si(R2SiO)2]2Zr (6b), which are derived from the reaction of 5 with M(NEt2)4, respectively. In the presence of TiCl4, complexes 6a and 7a undergo a ring-opening reaction to produce the dinuclear complex [Me2Si(R2SiO)2][TiCl3]2 (9). [Me2Si(R2SiO)2]TiMe2 (10) and [Me2Si(R2SiO)2]TiBnz2 (11) were prepared in moderate yields from reactions of 7a with 2 equiv of MeMgBr and BnzMgCl, respectively. According to NMR spectroscopic investigations, the reaction of the dimethyltitanium complex 10 with B(C6F5)3 led to full exchange of both methyl groups by C6F5 groups under quantitative formation of [Me2Si(R2SiO)2]Ti(C6F5)2 (12) and a mixture of B(C6F5)(3-n)Me(n), where n = 1-3. The structure of 12 is further evidenced by the preparation of an identical sample from the reaction of 7a with 2 equiv of C6F5MgBr. Refluxing an ether solution of 12 surprisingly gave [Me2Si(R2SiO)2]2TiC6F5]2O (13) as a result of ether cleavage. The structures of the complexes 7a, 7b, 9, 10, and 13 were determined by X-ray crystallography, and structural discussion of the bond parameters will be given.

Polyhedral Cobalt(II) and Iron(II) Siloxanes: Synthesis and X-ray Crystal Structure of [(RSi(OH)O2)Co(OPMe3)]4 and [(RSiO3)2(RSi(OH)O2)4(μ3-OH)2Fe8(THF)4] (R = (2,6-iPr2C6H3)N(SiMe3))

The cobalt(II) and iron(II) siloxane compounds were prepared by the reaction of lipophilic N-bonded silanetriol 1 with metal silylamides M[N(SiMe3)2]2 (M = Co (2), Fe (3)) in a 1:1 and 3:4 molar ratio, respectively. A plot of 1/chi versus temperature in the range of 2-300 K indicates the paramagnetic behavior of 2 and 3. The composition and molecular structures of 2 and 3 were fully determined by IR, elemental analysis, and X-ray crystal structural analyses. Compound 2 possesses a pseudo-4-fold (S4) symmetry, whereas 3 reveals an inversion center. Compound 2 represents a tetracobalt(II) drum while 3 exhibits an octairon(II) cage containing siloxane ligands.

Synthesis and x-ray crystal structure of [(THF)Zn(O(2)(OH)SiR)](4) (R = (2,6-i-Pr(2)C(6)H(3))N(SiMe(3))): enroute to larger aggregates

Reaction of aminosilanetriol RSi(OH)(3) (1) (R = (2,6-i-Pr(2)C(6)H(3))N(SiMe(3))) with diethyl zinc at room temperature in 1:1 stoichiometric ratio affords [(THF)Zn(O(2)(OH)SiR)](4) (2) (R = (2,6-i-Pr(2)C(6)H(3))N(SiMe(3))) in good yield. The single-crystal X-ray diffraction studies reveal that 2 is monoclinic, P2(1), with a = 17.117(3) A, b = 16.692(5) A, c = 17.399(4) A, alpha = gamma = 90 degrees, beta = 91.45(7) degrees, and Z = 2. The molecular structure of 2 contains two puckered eight-membered Zn(2)Si(2)O(4) rings, which are connected by the Zn-O bonds and form two planar four-membered Zn(2)O(2) rings. Compound 2 contains an unreacted hydroxyl group on each silicon atom, and hence, we carried out the reactions of 2 with dimethylzinc and methyllithium to form [Zn(4)(THF)(4)(MeZn)(4)(O(3)SiR)(4)] (3) (R = (2,6-i-Pr(2)C(6)H(3))N(SiMe(3))) and [(L)ZnLi(O(3)SiR)](4) (4) (L = 1,4-(Me(2)N)(2)C(6)H(4), R = (2,6-i-Pr(2)C(6)H(3))N(SiMe(3))), respectively. This suggested that 2 could be an intermediate product formed during the synthesis of 3 and 4.

Halogenodisilanes: precursors for new disilane derivatives

Starting from hexachloro- or hexabromodisilane a wide variety of 1,2-disubstituted tetrachlorodisilanes (RSiCl2SiCl2R) [R = Cp (2a), 4-iPrC6H4(SiMe3)N (2b), 2,6-iPr2C6H3(SiMe3)N (2c), (Me3Si)2CH (2d) (Me3Si)3C (2e), (Me3Si)3Si (2f)], tetrabromodisilanes (RSiBr2SiBr2R) [R = Cp (3a), 4-iPrC6H4(SiMe3)N (3b), (Me3Si)3Si (3f)] and the monosubstituted pentahalogenodisilanes CpSiX2SiX3 [X = Cl (4), Br (5)] were prepared. The tetrachlorodisilanes 2a-e are converted to various functionalized disilanes. Ammonolysis of 2a-e leads to the tetraaminodisilanes [RSi(NH2)2Si(NH2)2R] 6a-e. A reduction of 2d with LiAlH4 resulted in the formation of the disilane RSiH2SiH2R [R = (Me3Si)2CH] 7 and the metathesis with Me3SnF yielded the tetrafluorodisilane RSiF2SiF2R [R = (Me3Si)2CH] 8. Treatment of 6d with reagents containing H acidic protons (HX) [X = Br, I and OH] leads under elimination of NH3 to the tetrabromo- R2SiBr2SiBr2R (3d) tetraiodo- RSiI2SiI2R (9) and the tetrahydroxodisilane RSi(OH)2Si(OH)2R (10) [R = (Me3Si)2CH]. Single-crystal X-ray structural analysis of 2d, 6a, 6d, and 9 are reported.