Chapter 12. Organometallic chemistry. Part (ii) Main-group elements

Abstract

It is of interest to note here, incidently, that the unsubstituted silabarellene (25), like barellene itself, undergoes photochemical rearrangement to the 1 -silasemibullvalene (26). In contrast to semibullvalene itself, however, which undergoes a degenerate 3,3-shift at -150 "C with an activation energy of only 20 kJ mol-', the 1 -sila-species appears to be static, even at + 150 0C.40Returning to the sila-alkenes, however, it is obviously much more satisfactory to have stable species to examine, and in this regard 1982 has been an exciting year. The stable silaethylene [(Me3Si),Si=C(OSiMe3)(Cl0H15)3 (where CloH15 =

Metallaborane reaction chemistry. Part 12. Some interactions of acetylenes and isocyanides with selected metallaboranes

“…Its structure is perhaps best approximated in terms of a nido-type {H 2 CB 6 H 6 CHPh} unit (schematic III, in which unlabelled vertices represent BH(exo) units) in which the two CH(endo) hydrogen atoms are replaced by bonds to the {Pt(PMe 2 Ph) 2 } moiety (schematic IV), resulting in an essentially square planar configuration at the metal centre with much weaker interaction (hatched intracluster connectivity lines in structure IV) with the nearestneighbour boron atoms. Electronic features that contribute to this type of phenomenon in platinaboranes and platinaheteroboranes are adequately discussed elsewhere [15,39,40]. …”