The title compound, C18H26B9PS.CHCl3 is shown to have an arachno ten-v
ertex {6-SB9H11} cluster structure with a PPh3 ligand in the exo-9-pos
ition. The two bridging H atoms occupy asymmetric positions [average B
-H-bridge values 1.21(4) and 1.35(4) Angstrom] displaced away from the
S atom.