Facile Preparation of Chloro-Cage-Substituted 11-Vertex 1-(η6-Arene)-isonido-1,2,4-ruthenacarboranes from [RuCl2(PPh3)3] and nido-5,6-C2B8H12 in Arene Solvents

Abstract

A series of arene-ruthenium 11-vertex complexes 3-Cl-1-(η 6 -arene)- isonido -1,2,4-RuC 2 B 8 H 9 ( 4a - 4h ) and 6-Cl-1-(η 6 -arene)- isonido -1,2,4-RuC 2 B 8 H 9 ( 5a , 5b , 5f , 5g ) (arene = p -xylene ( a ), mesitylene ( b ), p -cymene ( c ), benzene ( d ), toluene ( e ), hexamethylbenzene ( f ), 1,2,4,5-tetramethylbenzene ( g ), 1,2,4-trimethylbenzene ( h )) have been obtained as isomeric mixtures 4a , 4b , 4f , 4g and 5a , 5b , 5f , 5g or, predominantly, as single isomers 4c - 4e , 4h by the treatment of nido -5,6-C 2 B 8 H 12 ( 1 ) with [RuCl 2 (PPh 3 ) 3 ] ( 2 ), either in the corresponding arene solvents at 80-85 °C (in the case of 4a - 4e and 5a , 5b ) or in the arene/1,2-dichloroethane solution under reflux (in the case of 4f - 4h and 5f , 5g ) in the presence of N , N , N' , N' -tetramethylnaphthalene-1,8-diamine. The compounds prepared were characterized by combination of analytical, IR and multinuclear NMR data, including a crystallographic study of 4b . A possible pathway for the formation of isomeric complexes 4 and 5 is discussed.