Wing Y. Man

How to Make 8,1,2‐closo‐MC2B9 Metallacarboranes

Three examples of the rare 8,1,2-closo-MC2B9 isomeric form of an icosahedral metallacarborane have been isolated as unexpected trace products in reactions. Seeking to understand how these were formed we considered both the nature of the reactions that were being undertaken and the nature of the coproducts. This led us to propose a mechanism for the formation of the 8,1,2-closo-MC2B9 species. The mechanism was then tested, leading to the first deliberate synthesis of an example of this isomer. Thus, deboronation of 4-(η-C5H5)-4,1,8-closo-CoC2B10H12 selectively removes the B5 vertex to yield the dianion [nido-(η-C5H5)CoC2B9H11](2-), oxidative closure of which affords 8-(η-C5H5)-8,1,2-closo-CoC2B9H11 in moderate yield.

Definitive crystal structure of 1,1'-bis-[1,2-dicarba-closo-dodeca-borane(11)].

In the title compound, the two {1,2-closo-C2B10H11} cages are linked across a centre of inversion with a C—C distance of 1.5339 (11) Å. By careful analysis of the structure, it is established that the non-linking cage C atom is equally disordered over cage vertices 2 and 3.

14‐Vertex Heteroboranes with 14 Skeletal Electron Pairs: An Experimental and Computational Study

Three isomers of [(Cp*Ru)2 C2 B10 H12 ], the first examples of 14-vertex heteroboranes containing 14-skeletal electron pairs, have been synthesized by the direct electrophilic insertion of a {Cp*Ru(+) } fragment into the anion [4-Cp*-4,1,6-RuC2 B10 H12 ](-) . All three compounds have the same unique polyhedral structure having an approximate Cs symmetry and featuring a four-atom trapezoidal face. X-ray diffraction studies could confidently identify only one of the two cage C atoms in each structure. The other C atom position has been established by a combination of i) best fitting of computed and experimental (11) B and (1) H NMR chemical shifts, and ii) consideration of the lowest computed energy for series of isomers studied by DFT calculations. In all three isomers, one cage C atom occupies a degree-4 vertex on the short parallel edge of the trapezium.

Crystal structure of a second polymorph of 2-cyclo-penta-dienyl-1,7-dicarba-2-cobalta-closo-dodeca-borane(11).

A new polymorph of the title compound 2-(η-C5H5)-2,1,7-closo-CoC2B9H11, [Co(C5H5)(C2H11B9)], in the space group P21/n has been characterized, including the unambiguous location of both cage C atoms. The precision of this study is an order of magnitude greater than that of the first polymorph [C2/c; Lopez et al. (2010). Collect. Czech. Chem. Commun. 75, 853–869].

Reduction-induced facile isomerisation of metallacarboranes: synthesis and crystallographic characterisation of 4-Cp-4,1,2-closo-CoC2B9H11

One-electron reduction of 3-Cp-3,1,2-closo-CoC2B9H11 followed by heating to reflux in DME (b.p. 85 °C) induces isomerisation to 4-Cp-4,1,2-closo-CoC2B9H11, a compound previously only synthesised at much higher temperatures (>380 °C). The 4,1,2-isomer has been thoroughly characterised both spectroscopically and crystallographically.