Two aikylarnirio-benzamidinates, [RNC(Ph)NCH2CH 2NMe2]- (ArL, R = 2,6-iPr 2C6H3; SiL, R = SiMe3), have been employed as ligands for Fe(II). The ligands adopt bridging coordination modes in their diiron(II) dichloro complexes [(μ- RL)FeCl]2 (1). Their structure and reactivity are strongly dependent on the nature of R. With CO, [(μ-Ar)FeCl]2 (1a) forms the monomelic, 18-electron dicarbonyl compound [κ3- C(O)(2,6-iPr2C6H3)NC(Ph)NCH2CH 2NMe2]FeCl(CO)2 (3), in which CO has inserted into the Fe-N(amidinate) bond, whereas [(μ-SiL)FeCl]2 (1b) is unreactive under similar conditions. Alkylation of 1a was unsuccessful, leading to ligand redistribution and isolation of (κ2- ArL)2Fe (2), in which the ligands adopt a κ2-amidoamino coordination mode, but 1b reacts with KCH2Ph to give the 14-electron diiron dibenzyl derivative [(μ-SiL)FeCH 2Ph]2 (4). Benzyl abstraction by B(C6F 5)3, [Ph3C][B(C6F5) 4], or [PhNHMe2][B(C6F5) 4] affords the paramagnetic monocation [(μ-SiL) 2Fe2CH2Ph]+ (5+) partnered with [PhCH2B(C6F5)3] -" or [B(C6F5)4]-, respectively. Interactions of these weakly coordinating anions with the paramagnetic Fe(II) centers in solution are apparent from significantly shifted and broadened resonances in the 19F NMR spectra.