A Distorted Trigonal Antiprismatic Cationic Silicon Complex with Ureato Ligands: Syntheses, Crystal Structures and Solid State Si-29 NMR Properties

作者：Schoene Dana; Gerlach Daniela; Wiltzsch Conny; Brendler Erica; Heine Thomas; Kroke Edwin^*; Wagler Joerg

来源：European Journal of Inorganic Chemistry, 2010, (3): 461-467.

DOI：10.1002/ejic.200900784

• Silicon
• Chelates
• Density-functional calculations
• Hypercoordination

Insertion of phenyl isocyanate into the Si-N bond of N-(trimethylsilyl)diethylamine yields the N'-silylated N,N-diethyl-N'-phenylurea 1, which undergoes transsilylation with SiCl4 to yield the C-3-symmetric cationic hexacoordinate silicon complex 3s(+) [tris-K-O,N'-(N,N-diethyl-N'-phenylureato)siliconium] as chloride salt, which was characterized crystallographically. The cationic complex 3s(+) exhibits a distorted trigonal antiprismatic coordination sphere about the silicon atom with fac arrangement of the three N-atoms (and the three O-atoms) relative to one another. This C-3-symmetric complex undergoes isomerization into its asymmetric isomer 3a(+) (mer arrangement of NNN or OOO relative to one another) in CDCl3 solution. Hence, two Si-29 NMR signals appear and four sets of signals emerge in the H-1 and C-13 NMR spectra. Despite its pronounced axial symmetry, the Si-29 NMR shielding tensor of the cation 3s(+) in its chloride salt exhibits an unusually small span (less than 20 ppm), which was analyzed CP/MAS NMR spectroscopically and by computational methods.

• 出版日期2010-1