Synthesis and Reactivity of Silicon Transition Metal Complexes, 34. Pentachlordisilanyl‐ und Disilanyl‐Komplexe von Molybdän und Wolfram: Darstellung, Struktur und spektroskopische Charakterisierung

Reactions of (mesityl)n(methyl)2-nsilylene complexes with pyridine-N-oxide (n = 1 and 0): formation of silanone complexes and a disiloxanyloxy complex

Silanones (OSiR2), a heavier congener of ketones (R2CO), are highly reactive species that are readily converted to oligomeric siloxane (O-SiR2)n. Coordination of silanones to the transition-metal fragments to afford silanone-coordinated complexes is a reliable silanone stabilization method. Recently, our group reported the synthesis, structures, and reactivity of dimesityl-substituted silanone complexes Cp*(OC)2M{OSiMes2(L)}(SiMe3) (M = W, Mo, L: Lewis base, Cp*: η5-C5Me5, Mes: 2,4,6-Me3C6H2). Herein, to investigate the effect of substituents on the silicon atom during the formation of a silanone complex, we demonstrated the use of Mes and smaller Me groups. As a result, the formation of Mes(Me)-substituted silanone molybdenum complex Cp*(OC)2Mo{OSiMes(Me)(py)}(SiMe3) (5b, py: pyridine) was suggested, the silanone tungsten complex Cp*(OC)2W{OSiMes(Me)(DMAP)}(SiMe3) (4a, DMAP: 4-(dimethylamino)pyridine) was obtained, and a dimethyl-substituted disiloxanyloxy(dioxo) complex Cp*(O)2W(OSiMe2OSiMe3) (9) was formed. The reaction of 4a with PMe3 proceeded via the elimination of DMAP and migration of the SiMe3 group to the oxygen atom of the silanone ligand to afford Cp*(OC)2W(SiMes(Me)OSiMe3)(PMe3) (11a). The Mo complex Cp*(OC)2Mo(SiMes(Me)OSiMe3)(PMe3) (11b) was produced by the reaction of Cp*(OC)2Mo{SiMes(Me)}(SiMe3) (7b) with pyridine-N-oxide in the presence of PMe3.

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.