Trigonal-lantern dinuclear compounds of diiron(I,II): The synthesis and characterization of two highly paramagnetic Fe-2(amidinato)(3) species with short metal-metal bonds .1.

Two examples of a new type of trigonal-lantern compound in which a formal Fe-2(3+) unit is bridged by three amidinato groups are formed by reacting FeCl2(HDPhF)(2) (HDPhF=N,N'-diphenylformamidine) and FeCl2(HDPhBz)(2) (HDPhBz=N,N'-diphenylbenzamidine) with NaEt3BH and methyllithium in THF. The isolated crystalline products, Fe-2(amidinato)(3), have been structurally characterized by X-ray crystallography at -60 degrees C. Crystal data for Fe-2(DPhF)(3) (I): monoclinic, space group C2/c, a=17.154(4), b=8.255(1), c=23.400(5) Angstrom, beta=93.38(1)degrees, Z=4; and for Fe-2(DPhBz)(3) . 2C(6)H(6) (II): trigonal, space group <R(3)over bar>c, a=11.237(2), c=76.510(7) Angstrom, Z=6. The Fe-Fe bond distances, 2.2318(8) and 2.198(2) Angstrom for compounds I and II, respectively, are the shortest known for any diiron compound. The room temperature magnetic susceptibilities of 7.81 and 7.53 B.M. for I and II and the EPR spectrum of I in a toluene glass (10 K) which shows two signals at g values of 1.99 and 7.94 are consistent with the presence of seven unpaired electrons in an axially symmetric environment.