Trimetallic FePd2 and FePt2 4-ferrocenyl-NCN pincer complexes

Ferrocene-bridged NCN pincer complexes of structural type Fe(η5-C5H4-4-NCN-1-MX)2 (X = I: 6, M = Pd; 7, M = Pt; X = Cl: 8, M = Pt; NCN = [4-C6H2(CH2NMe2)2-2,6]−) are accessible by the subsequent reaction of Fe(η5-C5H4-4-NCNH)2 (4) with nBuLi and [PtCl2(SEt2)2] (synthesis of 8) or treatment of Fe(η5-C5H4-4-NCN-1-I)2 (5) with [Pd2(dba)3] (synthesis of 6) or [Pt(tol)2(SEt2)]2 (synthesis of 7) (dba = dibenzylidene acetone, tol = 4-tolyl). In addition, the Sonogashira cross-coupling of Fe(η5-C5H4I)2 (1) with HCtriple bond; length of mdashC-4-NCNH (2) gives Fe(η5-C5H4-Ctriple bond; length of mdashC-4-NCNH)2 (3). The reaction behavior of 3 towards tBuLi is reported as well. Cyclovoltammetric studies show that the ferrocene entity can be oxidized reversibly. The Fe(II)/Fe(III) potential decreases with increasing electron density at the NCN pincer units due to the presence of the M-halide moiety (M = Pd, Pt). The solid state structure of Fe(η 5-C5H4-4-NCN-1-PdI)2 (6) is presented. In 6 the Fe(η 5-C5H4)2 unit connects two NCN-PdI pincer entities with palladium in a square-planar environment. The cyclopentadienyl ligands show a staggered conformation. The C6H2 rings are tilted by 23.5(3)° towards the C5H4 entities and the C6H2 plane is almost coplanar with the View the MathML sourcePdN2ipsoCI coordination plane (10.3(3)°).