Aggregation of [((t)Bu3SiS)MX]: Structures of {[Br2Fe(mu-(SSiBu3)-Bu-t)(2)FeBr(THF)]Na(THF)(4)}infinity, cis-[(THF)FeI](2)(mu-(SSiBu3)-Bu-t)(2), [((Bu3SiS)-Bu-t)Fe](2)(mu-(SSiBu3)-Bu-t)(2), and comparative structure and magnetism studies of [((Bu3SiS

摘要

A convenient synthesis of (Bu3SiSH)-Bu-t and (Bu3SiSNa)-Bu-t(THF)(x) led to the exploration of "(Bu3SiSMX)-Bu-t" aggregation. The dimer, [((Bu3SiS)-Bu-t)Fe](2)(mu-(SSiBu3)-Bu-t)(2) (1(2)), was formed from [{(Me3Si)(2)N}Fe](2)(mu-N(SiMe3)(2))(2) and the thiol, and its dissolution in THF generated ((Bu3SiS)-Bu-t)(2)Fe(THF)(2) (1-(THF)(2)). Metathetical procedures with the thiolate yielded aggregate precursors [X2Fe](mu-(SSiBu3)-Bu-t)(2)[FeX(THF)]Na(THF)(4) (3-X, X = Cl, Br) and cis-[(THF)IFe](2)(mu-(SSiBu3)-Bu-t)(2) (4). Thermal desolvations of 3-Cl, 3-Br and 4 afforded molecular wheels [Fe(mu-X)(mu-(SSiBu3)-Bu-t)](12)(C6H6)(n) (5-FeX, X = Cl, Br) and the ellipse [Fe(mu-I)(mu-(SSiBu3)-Bu-t)](14)(C6H6), (6-Fel). Related metathesis and desolvation sequences led to wheels [Co(mu-Cl)(mu-(SSiBu3)-Bu-t)](12)(C6H6)(n) (5-CoCl) and [Ni(mu-Br)(mu-(SSiBu3)-Bu-t)](12)(C6H6)(n) (5-NiBr). The nickel wheel disproportionated to give, in part, [((Bu3SiS)-Bu-t)Ni](2)(mu-(SSiBu3)-Bu-t)(2) (7), which was also synthesized via salt metathesis. X-ray structural studies Of 12 revealed a roughly planar Fe2S4 Core, while 1-(THF)(2), 3-Br, and 4 possessed simple distorted tetrahedral and edge-shared tetrahedral structures. X-ray structural studies revealed 5-MX (MX = FeCl, FeBr, CoCl, NiBr) to be wheels based on edge-shared tetrahedra, but while the pseudo-D-6d wheels of 5-FeCl, 5-CoCl, and 5-FeBr pack in a body-centered arrangement, those of pseudo-C-6v 5-NiBr exhibit hexagonal packing and two distinct trans-annular d((BrBr)-Br-. . .). Variable-temperature magnetic susceptibility measurements were conducted on 5-FeCl, 5-CoCl, 5-FeBr, and 6-Fel, and the latter three are best construed as weakly antiferromagnetic, while 5-FeCl exhibited modest ferromagnetic coupling. Features suggesting molecular magnetism are most likely affiliated with phase changes at low temperatures.