Icosahedral and supraicosahedral naphthalene ruthenacarboranes

The naphthalene ruthenacarboranes 3-(η-C10H8)-3,1,2-closo-RuC2B9H11 (1), 4-(η-C10H8)-4,1,6-closo-RuC2B10H12 (2) and 4-(η-C10H8)-4,1,10-closo-RuC2B10H12 (4) have been synthesised by the general method of reaction of a carborane dianion with [RuCl2(COD)]x in the presence of excess naphthalene under THF reflux. Compounds 4-(η-C10H8)-4,1,8-closo-RuC2B10H12 (3) and 4-(η-C10H8)-4,1,12-closo-RuC2B10H12 (5) were prepared from 2 and 4, respectively, by thermolysis in refluxing toluene. Compounds 1–5 were characterised spectroscopically and crystallographically. For the supraicosahedral ruthenacarboranes 2–5 the main structural point of interest was the conformation of the naphthalene ligand with respect to the ruthenacarborane cage, in comparison with conformations of the analogous ferracarboranes 4-(η-C10H8)-4,1,x-closo-FeC2B10H12 previously studied computationally. Good agreement is found between experimental and computational conformations for compounds 2, 3 and 4. Crystallographic disorder in 5 renders comparison between theoretical and experimental conformations difficult in this case.

Graphical abstract13-vertex naphthalene ruthenacarboranes 4-(η-C10H8)-4,1,x-closo-RuC2B10H12 (x = 6, 8, 10 and 12) have been prepared and their structures determined. The conformations of the naphthalene ligand with respect to the ruthenacarborane cage in these compounds are in generally good agreement with the conformations in the analogous ferracarboranes 4-(η-C10H8)-4,1,x-closo-FeC2B10H12 previously studied computationally.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► A general synthetic method for the preparation of naphthalene ruthenacarboranes is described. ► Four isomeric 13-vertex naphthalene ruthenacarboranes are synthesised and characterised. ► Structures of all these compounds are determined crystallographically. ► The molecular conformations found agree well with previous theoretical predictions.