Superclusters: A Host–Guest Complex with a Cyclic Array of Three Bridged MoFe₃S₄ Clusters

Syntheses, Structures and Magnetic Properties of New Chalcogen‐Bridged Heterodimetallic Cluster Compounds with Heterocubane Structure

“…Much effort was put into the synthesis of compounds that are capable of mimicking these active centres, and the discovery of vanadium as part of a heterodimetallic cluster in nitrogenase9 led to an increasing interest in examining heterocubanes containing group 5 transition metals 10,11. Thus, a number of compounds are known with an [M 4– x M′ x E 4 ] cluster core containing M = Mo, W, V; M′ = Fe, Cu and E = S, such as the compounds (Me 4 N)[VFe 3 S 4 Cl 3 (dmf) 3 ], (Me 4 N)[MoFe 3 S 4 (LS 3 )(Cl 4 ‐cat)(dmf)] (LS 3 = trithiol ligand, Cl 4 ‐cat = tetrachlorocatecholate),12 and (Et 4 N) 3 [W 2 Fe 6 S 8 (SPh) 6 (OMe) 3 ],13 that contain single heterocubanes and the compounds (Bu 4 N) 4 [(Cl 4 ‐cat)( n Pr 3 P)MoFe 3 S 4 (BH 4 ) 2 ]14 and (Et 4 N) 3 [{Cl 4 ‐cat)( n Pr 3 P)MoFe 3 S 4 Cl} 3 (μ‐SCH 2 Ph) 3 ]15 with double or triply bridged heterocubanes, respectively, whereas only a few candidates were synthesized featuring the same cluster motif with M = Nb, Ta, M′ = Fe, Co, Ni, Cu and E = S, Se, for example [Ta 2 Ni 2 E 4 Cl 4 (PPh 3 ) 2 (CH 3 CN) 2 ] (E = S, Se), [TaCo 3 S 4 (NCS) 3 (P t Bu 3 ) 3 ],16 and (Et 4 N) 3 [Nb 2 Fe 6 S 8 (SEt) 9 ] 17. In continuation of earlier work,11,16 we want to present here syntheses and structure determinations (in the figures all hydrogen atoms are omitted for clarity) of new heterocubane‐like compounds containing either niobium or tantalum combined with the electron‐rich transition metals iron, cobalt or nickel, as well as the results of magnetic measurements performed on selected examples of these clusters.…”