The salts Na[H2B(tttBu)2] and Na[HB(tttBu)3] (tttBu = 1-tert.butyl-5-thiotetrazole have been used to provide the new metallaboratranes [Ru(CO)(PPh3){κ4-B,S,S′,S′′-B(tttBu)3}], [IrH(CO)(PPh3){κ3-B,S,S′-BH(tttBu)2}] and [Ru(CO)(PPh3)2{κ3-B,S,S′-BH(tttBu)2}].