A synthetic method affording a topological analogue of the electron-transfer P-cluster of nitrogenase (Fe8S7(mu2-S-Cys)(2)) in the P-N state has been devised, based in part on our previous development of cubane-type VFe3S4 clusters (Hauser, C.; Bill, E.; Holm, R. H. Inorg. Chem. 2002, 41, 1615-1624). The cluster [(Tp)VFe3S4Cl3](2-) (1) is converted to [(Tp)VFe3S4(PR3)(3)](1+) (R = Et (2), Bu (3)) by reaction with R3P. The phosphine ligands are readily substituted, leading to [(Tp)VFe3S4(SR)(3)](2-) (R = Ph (4), H (5)). Reduction of 2 or 3 with cobaltocene produces the edge-bridged double cubanes [(TP)(2)V2Fe6S8(PR3)(4)] (R = Et (6), Bu (7)), which are readily converted to [(Tp)(2)V2Fe6S8(SPh)(4)](4-) (8). The structures of clusters 3-5 and 8 were proven crystallographically. Cluster 8 has the double-cubane structure previously shown for 6, in which two cubane units are bridged by two Fe-(mu(4)-S) bonds. Fe-57 isomer shifts are consistent with the formulation [VFe32.33+S4](2+) for the single cubanes and the allferrous description 2[VFe32+S4](1+) for the double cubanes. Reaction of 6 with 4 equiv of (Et4N)(HS) in acetonitrile results in the insertion of sulfide with concomitant structural rearrangement and the formation of [(TP)(2)V2Fe6S9(SH)(2)](4-) (10), obtained in ca. 50% yield as the Et4N+ salt. The cluster has C-2 symmetry, with two all-ferrous VFe3S4 fragments bridged by a common mu(6)-S atom and two mu2-S atoms that simulate the bridging atoms in the two Fe-(mu(2)-S-Cys)-Fe bridges of the P-N cluster. The bridge pattern V2Fe6(mu(2)-S)(2)(mu(3)-S)(6)(mu(6)-S) and cluster shape match those of the native cluster. A best-fit superposition of the cores of 10 and the P-N cluster affords a weighted rms deviation in atom positions of 0.33 Angstrom. Cluster 10 and [(TP)(2)Mo2Fe6S9(SH)(2)](3-), prepared by a related route (Zhang, Y.; Holm, R. H. J Am. Chem. Soc. 2003, 125, 3910-3920), demonstrate that the topology of the P-N cluster can be achieved in molecular form in the absence of protein structure (Tp = tris(pyrazolyl)hydroborate).