The Solitary Isomer of C60 H18 Is Proven to Have a C3v Crown Shape: Crystal Structure Determination and Synthesis of Its Triruthenium Cluster Complex

Analytically pure C60 H18 is obtained by a Ru3 cluster complexation and decomplexation method. The crystal structure of C60 H18 consists of one flattened hemisphere, to which all 18 hydrogen atoms are symmetrically bonded, and one curved hemisphere akin to C60 . A benzenoid ring in the flattened hemisphere is isolated from the residual π systems by a belt composed of sp(3) -hybridized CH units. The average out-of-plane distances for carbon atoms attached to the benzenoid ring (0.14 Å) is substantially larger than that found in C60 F18 (0.06 Å). Several long C(sp(3) )C(sp(3) ) single bond lengths [1.61(3)-1.65(3) Å] are observed for C60 H18 . The reaction of [Ru3 (CO)12 ] and C60 H18 produces [Ru3 (CO)9 (μ3 -η(2) ,η(2) ,η(2) -C60 H18 )] (1), where the Ru3 triangle is regiospecifically linked to the hexagon opposite to the benzenoid ring. Compound 1 is the first transition metal complex of a polyhydrofullerene (fullerane). C60 H18 and 1 have been characterized by (1) H and (13) C NMR, UV/Vis, and mass spectroscopies. The HOMO-LUMO gap of C60 H18 is evaluated to be 1.51 V by cyclic voltammetry.

Thermodynamic rearrangement synthesis and NMR structures of C1, C3, and T isomers of C60H36

The structures of three C60H36 isomers, produced by high-temperature transfer hydrogenation of C(60) in a 9,10-dihydroanthracene melt, was accomplished by 2D (1)H-detected NMR experiments, recorded at 800 MHz. The unsymmetrical C(1) isomer is found to be the most abundant one (60-70%), followed by the C(3) isomer (25-30%) and the least abundant T isomer (2-5%). All three isomers are closely related in structure and have three vicinal hydrogens located on each of the 12 pentagons. Facile hydrogen migration on the fullerene surface during annealing at elevated temperatures is believed to be responsible for the preferential formation of these thermodynamically most stable C60H36 isomers. This hypothesis was further supported by thermal conversion of C60H36 isomers to a single C(3v) isomer of C60H18.