The reinvestigation of an early synthesis of heterometallic cubane-type clusters has led to the isolation of a number of new clusters which have been characterized by spectroscopic and crystallographic techniques. The thermolysis of [(Cp*Mo)2B4H4E2] (1: E = S; 2: E = Se; Cp* = η5-C5Me5) in presence of [Fe2(CO)9] yielded cubane-type clusters [(Cp*Mo)2(μ3-E)2B2H(μ-H) {Fe(CO)2}2Fe(CO)3], 4 and 5 (4: E = S; 5: E = Se) together with fused clusters [(Cp*Mo)2B4H 4E2Fe(CO)2Fe(CO)3] (8: E = S; 9: E = Se). In a similar fashion, reaction of [(Cp*RuCO)2B 2H6], 3, with [Fe2(CO)9] yielded [(Cp*Ru)2(μ3-CO)2B2H(μ- H){Fe(CO)2}2Fe(CO)3], 6, and an incomplete cubane cluster [(μ3-BH)3(Cp*Ru) 2{Fe(CO)3}2], 7. Clusters 4-6 can be described as heterometallic cubane clusters containing a Fe(CO)3 moiety exo-bonded to the cubane, while 7 has an incomplete cubane [Ru 2Fe2B3] core. The geometry of both compounds 8 and 9 consist of a bicapped octahedron [Mo2Fe2B 3E] and a trigonal bipyramidal [Mo2B2E] core, fused through a common three vertex [Mo2B] triangular face. In addition, thermolysis of 3 with [Mn2(CO)10] permits the isolation of arachno-[(Cp*RuCO)2B3H7], 10. Cluster 10 constitutes a diruthenaborane analogue of 8-sep pentaborane(11) and has a structural isomeric relationship to 1,2-[{Cp*Ru} 2(CO)2B3H7]. © 2011 American Chemical Society.