Four nickelaundecaborane clusters have been isolated from the reaction of [NiCl~2(PPh~3)~2] with B~1~0H~1~0^2^- in the present of PhCOSH. Three of them [(PPh~3)(PhCOS)~2Ni· B~1~0H~1~0]·0.5C~6H~1~4 (1), [(PhCOS)~2NiB~1~0H~8(PPh~3)](2), [(PhCOS)~3NiB~1~0H~7(PPh~3)](3) were characterized by X-ray diffraction analysis. The clusters have nido 11-vertex {NiB~1~0} polyhedral skeletons with two, two and three exo-polyhedral cyclic Ni－S－C－O－B five-membered rings, respectively. The distance between boron atoms participating in exo- polyhedral cyclizations to nickel atom is shorter which shows that cyclization can strengthen the nickel-to-boron bonding.

Key words: BORANES, NICKEL COMPOUNDS, CLUSTER COMPOUND, CRYSTAL STRUCTURE, X-RAY DIFFRACTION ANALYSIS, FOUNDATION OF NATIONAL SCIENCE FOUNDATION COMMITTEE