A SOLID-STATE (NMR)-N-1 AND THEORETICAL-STUDY OF THE CHEMICAL BONDINGIN DISILENES

Nine disilenes have been studied by solid-state NMR spectroscopy, unde r static or slow magic-angle spinning conditions, to determine the Si- 29 chemical shift tensors. All of the compounds show strong deshieldin g along one axis and correspondingly large spreads of the tensor compo nents, Delta delta (=delta(11) -delta(33)) MO calculations on model di silenes indicate that the deshielding results from a paramagnetic cont ribution along the in-plane axis perpendicular to the Si-Si vector. Im plications of the NMR data and the theoretical camputations for Si=Si bonding are discussed.