Die Kristallstruktur von N,N,N'-tris(trimethylsilyl)benzamidin sowie die Synthese und Kristallstruktur von DichIorantimon-N,N'-bis(trimethylsilyl)benzamidinat

Abstract

Abstract N,N,N'-Tris(trimethylsilyl)benzamidine, [C6H5-C(NSiMe3)N(SiMe3)2], reacts with antimony trichloride in CH2Cl2 solution to form monomeric dichloroantimony-N,N'-bis(trimethylsilyl)- benzamidine, [SbCl2(NSiMe3)2C-C6H5]. Both benzamidine derivatives have been character­ized by crystal structure determinations. [C6H5-C(NSiMe3)N(SiMe3)2]: space group P21/c, Z = 4, 2278 observed independent refle­xions, R = 0,038. Lattice dimensions (19 °C): a = 1521,0(1); b = 656.7(1); c = 2163,0(1) β = 94,21(1)°. The compound forms monomeric molecules with CN distances of 126,6 pm, and 141,0 pm, respectively, corresponding to C=N̄-SiMe3 and C-N(SiMe3)2 moieties. [SbCl2(NSiMe3)2C-C6H5]: space group P21/c, Z = 4, 2707 observed independent reflexions, R = 0,027. Lattice dimensions (19 °C): a = 1212,7(1); b = 962,1(1); c = 1728,9(1) pm; β = 98,02(1)°. The compound forms monomeric molecules in which the antimony atom is surrounded by two chlorine atoms, and by the N atoms of the benzamidine chelate, forming a distorted trigonal bipyramidal arrangement, which is a consequence of the steric effect of the lone pair on the Sb atom.