MIXED GROUP-14 GROUP-14 BONDS .5. 6 PERPHENYLATED PROPANE ANALOGS PH3M-M'PH2-M''PH3 (M, M', M'' = SI/GE) - ELECTRONEGATIVITY DIFFERENCE BETWEEN SILICON AND GERMANIUM

The six title compounds have been synthesized from Li/K-Si/GePh3 and chloride precursors in THF, DME or diethyl ether at low temperature. The six compounds crystallize isomorphously in the space group Pbca with ordered arrangement for the four symmetrical cases (Si-Si 2.394, Si-Ge 2.412, Ge-Ge 2.440 angstrom) and statistical alignment for the two asymmetrical chains; angle range 116.5-123.3-degrees. Replacement of Si by Ge atoms leads to low field NMR chemical shifts for C-13(ipso) atoms and for directly bonded Si-29 atoms. This is in accordance with an enhanced electronegativity of germanium in comparison with silicon. UV/Vis and IR/Raman data are given.