Polydeckerkomplexe mit μ,η⁵-2,3-Dihydro-1,3-diborolylnickel-Fragmenten als Stapeleinheiten / Polydecker Complexes with μ,η⁵-2,3-Dihydro-1,3-diborolylnickel Fragments as Stacking Units

Abstract

Reactions of 2,3-dihydro-1,3-diboroles 6a–h with (C 3 H 5 ) 2 Νi lead to µ,η 5 -2,3-dihydro-1,3-diborolylnickel triple-decker complexes 7a –h. By slow heating these oily, diamagnetic complexes in a rotating flask polycondensation with formation of black 8a–h as well as of bis(allyl)nickel and hexadiene occurs. The latter can be removed under reduced pressure. The constitution of the polymeric material follows from EXAFS studies. The Ni–Ni distance is 3,35 A, the ring atom Ni bonds are in the range of 2,13 to 2,15 A. Thermogravimetric measurements between 200 and 400°C show a mass loss of 20-40%, depending of the alkyl substituents of the heterocycle. In dynamic difference calorimetry an endothermic process occurs near 420°C. The powder conductivity of the amorphous, air-sensitive material is in the range of 10 -2 S • cm -1 . Doping with iodine or oxygen causes a decrease in the conductivity of these semi-conductors.