The crystal structure of 1-cyanopropylsilatrane [NC(CH_2)_3 Si(OCH_2CH_2)_3N] has been determined by X-ray diffraction method. It's crystallized in orthorhombic, space group Pna2_1, with a=12.797(3), b=11.843(2), c= 8.163(2), and Z=4. The structure is solved by the direct method and refined by the block-diagonal least-squares. The initial R value is 0.379 and the final one is 0.078 for 1040 observable reflections. The result of the structure analysis indicates the presence of pentaeoordinate silicon. The molecular geometry of silicon is a distorted trigonal bipyramid. The transannular dative bond length between silicon and nitrogen is 2.164(4), the Si—C is 1.884(5). The angle of N—Si—C is 178.9(4)°. All the calculations are carried out using the (GC-80) (ALGOL 60) system of programs which were developed by one of the authors over the computer TQ-16 (32K, 48 bits)madein China.
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