In a single step, from [Cp*RuCl2](2) (Cp* = eta(5)-C5Me5) and Li[BH4], nido-1,2-(Cp*Ru)(2)Cu-H)(2)B3H7, 1, is produced in high yield. Addition of BH3. THF to 1 results in conversion to nido-1,2-(Cp*Ru)(2)(mu-H)B4H9, 2. Reaction of BH3. THF directly with [Cp*RuCl2](2) yields a mixture of (and 2. In two steps, a rhodium analogue, nido-2,3-(Cp*Rh)(2)B3H7, 9, is accessible by the reaction of [Cp*RhCl2](2) and Li[BH4] to exclusively produce (Cp*Rh)(2)B2H6, 8, which adds BH3. THF to give 9 as the major product in a mixture. Reaction of BH3. THF directly with [Cp*RhCl2](2) yields the chloro derivative of 9, nido-1-Cl-2,3-(Cp*Rh)(2)B3H6, 11, in high yield via the intermediate positional isomer, nido-3-Cl-1,2-(Cp*Rh)(2)B3H6, 10. With high concentrations of Co-2(CO)(8), 1 reacts with Co-2(CO)(8) to give nido-1-(Cp*Ru)-2-(Cp*RuCO)-3-Co(CO)(2)(mu(3)-CO)B3H6, 3 , whereas low concentrations permit competitive degradation of 1 to yield arachno-(Cp*Ru)(CO)(mu-H)B3H7, 4 On the other hand, reaction of 11 with Co-2(CO)(8) gives closo-1-Cl-6-{Co(CO)(2)}-2,3(Cp*Rh)(2)(mu(3)-CO)B3H3, 12 Mild thermolysis of 3 results in loss of hydrogen and the formation of closo-6-Co(CO)(2)-2,3-(Cp*Ru)(2)(mu-CO)(mu(3)-CO)B3H4, 5, whereas thermolysis of 2 results in loss of hydrogen and formation of pileo-2,3-(Cp*Ru)(2)B4H8, 6, with a BH-capped square pyramidal structure. Finally, 6 reacts with Fe-2(CO)(9) to yield pileo-6-Fe(CO)(3)-2,3-(Cp*Ru)(2)(mu(3)-CO)B4H4, 7, With a BH-capped octahedral cluster structure. The overall isolated yield of 7, formed in four steps from [Cp*RuCl2](2), is approximate to 50% and evidences good control of reactivity.