All three Fe-based clusters in the CSD were published between 2007-2010 and are heterometallic, two include Ge and one includes K. [Ge II 4(TBC [8])][Fe 0 2(CO)8] (22; Fig. ) was synthesised from the reaction of [Ge4(TBC [8])] with [Fe2(CO)9] in benzene. Complex 22 largely retains the same overall structural features of the [Ge II 4TBC [8]] starting material, in which two {Ge2O(Ph)2} rhombs occupy two separate halves of the molecule, related by a C2 axis. The two {Fe(CO)4} groups are bonded to the two Ge ions that are positioned outwith the central cavity of the TBC [8] ligand, pointing downwards with respect to the top of the ligand bowl. The TBC [8] ligand adopts a distorted saddle conformation, wrapping around the Ge ions such that four O(Ph) atoms are bonded to each {Ge2} pair; two terminally bonded and two µ-bridging. The Fe atoms are formally zero valent, with all four Ge ions in the +2 oxidation state. Interestingly, the same reaction but using the para-unsubstituted H8C [8] ligand results in the formation of [Ge IV 4(C [8])][Fe -I 2(CO)8]4 (23) (Fig. ). In this case the reaction proceeds via (an unexpected) reductive decarbonylation, with extrusion of one bridging CO group in [Fe2(CO)9] and the formation of four [GeFe2] three-membered rings, arranged in a tetrahedral fashion around the C [8] ligand. Formally, the reaction involves oxidation of Ge II to Ge IV and reduction of the diiron fragments to [Fe2(CO)8] 2-. The final Fe-based cluster in the database is the complex [Fe III 4K4O2(H2O)2(H2TBC [8])2(MeCN)6] (24; Fig. ) which results from the reaction of [K2Fe2(O t Bu)6(THF)2] with H8TBC [8] in toluene, followed by crystallisation from MeCN. The ASU in 24 contains a near-linear Fe-O-Fe dimer in which the µ4-O 2-ion further bridges to two K ions lying in a perpendicular plane. Both Fe ions are four coordinate and in distorted tetrahedral {FeO4} geometries, the other three O-atoms deriving from the H2TBC [8] ligand. Symmetry expansion reveals that the four K ions form a central square rhomb, connected by four and two bridging MeCN and H2O molecules, respectively. The hexa-deprotonated H2TBC [8] ligands adopt the double-cone conformation, and present an unusual bonding motif. Four O(Ph) atoms are µ-bridging between the Fe and K ions, two are terminally bonded to Fe ions, and the two protonated O-atoms are non-bonded. In the latter case, the associated Ph group bonds side-on (η 6 ) to a K ion.