Unexpected disproportionation of tetramethylethylenediamine-supported perchlorodisilane Cl3SiSiCl3.
The addition compound Cl(3)SiSiCl(3)·TMEDA was formed quantitatively by treatment of Cl(3)SiSiCl(3) with tetramethylethylenediamine (TMEDA) in pentane at room temperature. The crystal structure of Cl(3)SiSiCl(3)·TMEDA displays one tetrahedrally and one octahedrally bonded Si atom (monoclinic, P2(1)/n). (29)Si CP/MAS NMR spectroscopy confirms this structure. Density functional theory (DFT) calculations have shown that the structure of the meridional isomer of Cl(3)SiSiCl(3)·TMEDA is 6.3 kcal lower in energy than that of facial coordinate species. Dissolving of Cl(3)SiSiCl(3)·TMEDA in CH(2)Cl(2) resulted in an immediate reaction by which oligochlorosilanes Si(n)Cl(2n) (n = 4, 6, 8, 10; precipitate) and the Cl(-)-complexed dianions [Si(n)Cl(2n+2)](2-) (n = 6, 8, 10, 12; CH(2)Cl(2) extract) were formed. The constitutions of these compounds were confirmed by MALDI mass spectrometry. Additionally, single crystals of [Me(3)NCH(2)CH(2)NMe(2)](2)[Si(6)Cl(14)] and [Me(3)NCH(2)CH(2)NMe(2)](2)[Si(8)Cl(18)] were obtained from the CH(2)Cl(2) extract. We found that Cl(3)SiSiCl(3)·TMEDA reacts with MeCl, forming MeSiCl(3) and the products that had been formed in the reaction of Cl(3)SiSiCl(3)·TMEDA with CH(2)Cl(2). X-ray structure analysis indicates that the structures of [Me(3)NCH(2)CH(2)NMe(2)](2)[Si(6)Cl(14)] (monoclinic, P2(1)/n) and [Me(3)NCH(2)CH(2)NMe(2)](2)[Si(8)Cl(18)] (monoclinic, P2(1)/n) contain dianions adopting an "inverse sandwich" structure with inverse polarity and [Me(3)NCH(2)CH(2)NMe(2)](+) as countercations. Single crystals of SiCl(4)·TMEDA (monoclinic, Cc) could be isolated by thermolysis reaction of Cl(3)SiSiCl(3)·TMEDA (50 °C) in tetrahydrofuran (THF).
Institut für Anorganische Chemie, Goethe-Universität Frankfurt am Main, Max-von-Laue-Straße 7, 60438 Frankfurt am Main, Germany.
Jan
J
Tillmann
Frank
F
Meyer-Wegner
Andor
A
Nadj
Johanna
J
Becker-Baldus
Tanja
T
Sinke
Michael
M
Bolte
Max C
MC
Holthausen
Matthias
M
Wagner
Hans-Wolfram
HW
Lerner
D056831:Coordination Complexes / Q000737:chemistry*; D018360:Crystallography, X-Ray; D005025:Ethylene Dichlorides; D005029:Ethylenediamines / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D010472:Perchlorates / Q000737:chemistry*; D011789:Quantum Theory; D012821:Silanes / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013237:Stereoisomerism; D013696:Temperature; D013816:Thermodynamics
D056831:Coordination Complexes; D005025:Ethylene Dichlorides; D005029:Ethylenediamines; D010472:Perchlorates; D012821:Silanes; C005798:N,N,N',N'-tetramethylethylenediamine