An Electrochemical and Structural Study of the Iron Silylamides Fe[N(SiMe3)2]2 and Fe[N(SiMe3)2]3 (in German)

The bis(trimethyl)silylamido complex Na(THF){Fe[N(SiMe3)(2)](3)} and the disilane tBu(3)SiSitBu(3) were obtained from the reaction of Fe[N(SiMe3)(2)](3) with the sodium silanide Na(THF)(2)[SitBu(3)] in a mixture of benzene and THF. Single crystals of Na(THF){Fe[N(SiMe3)(2)](3)} suitable for X-ray diffraction were grown from the reaction solution at ambient temperature (orthorhombic, C222(1), Z = 4). The solid-state structure features a contact-ion pair with two short N Na contacts. The THF adducts {M(THF)(2)[N(SiMe3)(2)](2)) reacted with 2,2'-bipyridine to give the corresponding complexes {M(2,2'bipy)IN(SiMe3)(2)](2)} (M = Mn, Fe). Their structures ( M = Fe: orthorhombic, Pca2(1), Z = 8; M = Mn: orthorhombic, Pbca, Z = 8) feature monomeric units. The cyclic voltammogram of Fe[N(SiMe3)(2)](3) revealed a reversible redox transition with the potential of 0,523 V (E-1/2), which was assigned to the Fe(III)N(SiMe3)(2))(3) -> Fe(II)[N(SiMe3)(2)](3)(-) redox transition, whereas the compounds Fe(THF)2[N(SiMe3)(2)](2) (E-ox = 0,379 V) and {Fe(2,2ibipy)[N(SiMe3)2121 (E-ox = - 0,436 V) featured irreversible oxidation waves. The related manganese bis(trimethylsilyl)amido complexes {Mn(THF)2{N(SiMe3)(2)](2)) (E-ox = 0,458 V) and (Mn(2,2ibipy)[N(SiMe3)2]2} (E-ox = -0513 V) also underwent irreversibile electron transfer processes.