Computational studies of structures and properties of metallaboranes.: 2.: Transition-metal dicarbollide complexes

A density functional study at the BP86 level is presented for metal bis(dicarbollides), [3-M-(1,2-C2B9H11)(2)](n) (M/n = Fe,Ru/2-, Co,Rh/1-, Ni,Pd/0), as well as selected mixed- and half-sandwich complexes [3-M(L)-(1,2-C2B9H11)] {M(L) = Fe(C6H3Me3) Ru(C6H6), Ru(CO)(3), Rh(C5Me5)}. Available experimental B-11 NMR chemical shifts of these complexes with closo structure of the metallacarborane moiety are reproduced reasonably well at the GIAO-B3LYP/II' level, with mean absolute deviations of ca. 3 ppm (over a chemical-shift range of ca. 50 ppm). The potential usefulness of this computational protocol for assignments and structural refinements of transition-metal-containing heteroboranes is illustrated in an application to 14-vertex closo clusters [1,14-{(arene)Ru}(2)(x,y-C2B10H12), where the C-substitution pattern in the carborane moiety is identified.