Rhodri Ll. Thomas and Alan J. Welch
The closo carbaborane
1-(PhCC)-2-Ph-1,2-C2B10H10 was readily
decapitated to afford either
[7-(PhCC)-8-Ph-7,8-C2B9H10]
- or
[7-(PhCC)-8-Ph-7,8-C2B9H9]2
-. Reaction of the thallium(I) salt of the latter
with [{RuCl2(cym)}2]
(cym = p-cymene) yielded the unique
semipseudocloso carbaruthenaborane
[1-(PhCC)-2-Ph-3-(cym)-3,1,2-RuC2B9H9]
characterised by multinuclear NMR spectroscopy (weighted average
11B chemical shift +2.41 ppm) and by single-crystal X-ray
diffraction [C(1)–C(2) 2.184(7),
Ru(3)·
·
·
B(6)
3.166(6) Å]. The semipseudocloso shape thus appears to
lie between closo and pseudocloso, although somewhat
closer to the latter. Confirmation of the structure strongly supports
the idea of a continuum of cluster structures from closo to
pseudocloso, the position of a molecule on which may be
controlled by steric effects.