RANEOPENTYL-7,8-DISILABICYCLO[2.2.2]OCTA-2,5-DIENE AND RAISOPROPYL-7,8,DISILABICYCLO[2.2.2]OCTA-2,5-DIENE - INTERACTION WITH TETRACYANOETHYLENE AND TRANSITION-METAL CHLORIDES

7,7,8,8-tetraalkyl-7,8-disilabicyclo[2.2.2]octa-2, 5-dienes (1: R = (t )BuCH(2); 2: R = Pr-i) were prepared by the reaction of CIR(2)SiSiR(2) Cl with lithium anthracenide in 1,2-dimethoxyethane (DME) at room temp erature. The structure of 1 was determined by X-ray crystallography, C rystal data for 1: monoclinic, C2/c, a = 12.941(2), b = 14.601(1), c = 35.109(6) Angstrom, beta = 94.957(7)degrees, V = 6609(2) Angstrom(3), Z = 8, R = 0.045, R(w) = 0.053 for 4037 reflections. Compounds 1 and 2 show the bachochromic shift of (1)L(a) and (1)L(b) bands in UV spect ra and exhibit considerably low oxidation potentials due to effective sigma-pi conjugation. Compounds 1 and 2 form charge-transfer complexes with tetracyanoethylene (TCNE). In the case of 1, the charge-transfer complex (1: TCNE = 2: 1) could be isolated as crystals and the struct ure was determined by X-ray crystallography. Crystal data for the 1-TC NE complex: monoclinic, C2/c, a = 10.267(2), b = 36.077(4), c = 20.022 (4) Angstrom, beta = 100.680(8)degrees, V = 7288(2) Angstrom(3), Z = 4 , R = 0.045, R(w) = 0.077 for 4120 reflections. The action of transiti on metal chlorides on 2 resulted in [4 + 2] cycloreversion to form (Cl Pr2SiSiPr2Cl)-Pr-i-Pr-i and anthracene.