The title compound, [(PPh3)(p-MeC6H4COO)(2)RuB10H8], contains an 11-vertex
closo-type RuB10 cluster fused to two symmetric exopolyhedral Ru-O-C-O-B fi
ve-membered rings. Principal distances include Ru-B 2.010 (5)-2.392 (4) Ang
strom and Ru-O 2.218 (5) and 2.222 (2) Angstrom.