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

Abstract

The meta-diaminoaryl ferrocenes Fc-NCN-H (3) and Fc-C"C-NCN-H (5) (Fc = (g 5 -C 5 H 5 )(g 5 -C 5 H 4 )Fe, NCN-H = C 6 H 3 (CH 2 NMe 2 ) 2 -3,5) can be used as precursors in the preparation of heterobimetallic transition metal complexes of structural type Fc-NCN-MX (NCN = [C 6 H 2 (CH 2 NMe 2 ) 2 -2,6] À ; MX = PdCl (7), PtCl (8), PtI (9)) and Fc-C"C-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 SO 2 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 C 6 H 2 moiety is with 27.2(3)°and 38.2(3)°tilted towards the C 5 H 4 entity, while in 13 an angle of 45.9(3)°can be found. The d 8 -electron configured platinum atoms possess a somewhat distorted square-planar surrounding, setup by two Me 2 NCH 2 ortho-substituents, the NCN C ipso carbon atom and the chloride ligand.

Syntheses, Structures, and Electronic and Optical Properties of Platinum(II) Complexes of 1,3-Bis(imino)benzene-Derived Pincer Ligands

“…The Pt–Cl distances in 12 and 14 are as expected for NCN-pincer complexes. The Pt–N distances resemble those in other bIB – ,,,, and bPyB – complexes, while N - t Bu complexes have slightly longer Pt–N distances (2.08–2.10 Å), as do Pt II (bAB)X species …”

“…159° indicative of ring strain in the five-membered chelates, as in other NCN-pincer complexes. Pt II (bAB)X and Pt II (bPyB)X , complexes are less strained, with respective N–Pt–N angles of ca. 164 and 161° due to longer C–N distances.…”

Bimetallic complexes that merge metallocene and pincer-metal building blocks: synthesis, stereochemistry and catalytic reactivity

“…[93][94][95][96][97] Electrochemical properties of the SO 2coordinated (65) and the SO 2 -free compound (60) in solution were studied showing the different redox potentials of Fe(II) in the SO 2 -coordinated and SO 2 free state (Scheme 13). 87 These observations, both by colorimetric and voltametric analysis, revealed that the reduced electron density on Pt(II), caused by the SO 2 coordination, is relayed to the Fe atom of the ferrocene, thus causing a decrease of the Fe redox potential.…”

“…86 The Fe(II)/Fe(III) oxidation potential for the monometallic specie was 0.03 V, while for complex 58 this was −0.03 V. The set of metallocene-based pincer complexes of type B was expanded following two, different methodologies to obtain the respective CpFeC 5 H 4 (CC) n (NCN)Pd(II)Cl or Pt(II)Cl (n = 0 or 1) derivates, see (Scheme 12). 87,88 The first strategy comprised reaction of the metallocene-pincer precursor with n BuLi followed by a transmetallation reaction. The second strategy involved the synthesis of the iodide precursor from the organolithium complex.…”

Metal-Catalyzed Cross-Coupling Reactions for Ferrocene Functionalization: Recent Applications in Synthesis, Material Science and Asymmetric Catalysis

“…With PdCl 2 (dppf)/NaOH system, Köcher and colleagues obtained a low yield of (39) by coupling 3,5-(dimethylamino)methyl iodobenzene with ferrocene. Compound (39) was then used for NCN pincer complexes synthesis [37]. Ba(OH) 2 was used as the base by Cammidge and colleagues for the synthesis of face-to-face porphyrin-ferrocene systems [38].…”