TETRAKIS[(TRIMETHYLSILYL)ETHYNYL] GROUP-14 METAL DERIVATIVES - AN EXAMINATION OF THE ELECTRONIC INTERACTION BETWEEN 2 GROUP-14 METALS CONNECTED BY AN ACETYLENE WIRE

The tetrakis(trimethylsilyl)ethynyl derivatives of Si, Ge, Sn, and Pb were prepared and examined spectroscopically. NMR and Mossbauer spectr oscopy and X-ray crystal structure data clearly demonstrate an electro nic interaction in the ground state between the distal SiMe3 groups an d the central metal atom, leading to a strong shielding of the central metal atom; the respective nmr signals of the central metal are among the most shielded examples reported for a Group 14 metal centre with four carbon ligands. The nature of these electronic interactions is di scussed.