Heterobimetallic Fe–Pd and Fe–Pt NCN pincer complexes (NCN = [C6H2(CH2NMe2)2-2,6]−)

The meta-diaminoaryl ferrocenes Fc–NCN–H (3) and Fc–CC–NCN–H (5) (Fc = (η5-C5H5)(η5-C5H4)Fe, NCN–H = C6H3(CH2NMe2)2-3,5) can be used as precursors in the preparation of heterobimetallic transition metal complexes of structural type Fc–NCN–MX (NCN = [C6H2(CH2NMe2)2-2,6]−; MX = PdCl (7), PtCl (8), PtI (9)) and Fc–CC–NCN–MX (MX = PdCl (11), PdI (12), PtCl (13)), respectively. They are accessible by applying different synthesis procedures, including oxidative addition and metallation–transmetallation processes.Cyclovoltammetric studies show that the ferrocene moieties in 3, 5, 7–9 and 11-13 can reversibly be oxidised. The potential of the Fe(II)/Fe(III) redox couple decreases with increasing electron density at the NCN pincer unit. The use of 8 as a possible (electro)chemical sensor in the detection of SO2 is discussed as well.The solid-state structures of 8 and 13 are reported. The crystals of 8 contain two molecules of 8 in the asymmetric unit. The plane of the C6H2 moiety is with 27.2(3)° and 38.2(3)° tilted towards the C5H4 entity, while in 13 an angle of 45.9(3)° can be found. The d8-electron configured platinum atoms possess a somewhat distorted square-planar surrounding, setup by two Me2NCH2ortho-substituents, the NCN Cipso carbon atom and the chloride ligand.

Graphical abstractThe synthesis and electrochemical behaviour of mononuclear and heterobimetallic complexes of structural type Fc–NCN–X and Fc–CC–NCN–X (X = H, I, PdCl, PdI, PtCl, PtI) is reported. The solid-state structure of two examples is discussed.Figure optionsDownload full-size imageDownload as PowerPoint slide