Synthesis and Electrochemical Behavior of Metal Carbonyl Isocyanoferrocene Compounds [M(CO)6‐n(C≡NFc)n] (M=Cr, Mo, W; n=1, 2, 3)

Abstract

AbstractThe synthesis of [M(CO)6‐n(C≡NFc)n] (n=1: M=Cr, 3 a; M=Mo, 3 b; M=W, 3 c. n=2: M=Mo, 5. n=3: M=Mo, 6. Fc=Fe(η5−C5H4)(η5−C5H5)) by the reaction of [M(CO)5(thf)] (M=Cr, 1 a; M=Mo, 1 b; M=W 1 c) (synthesis of 3 a–c), [Mo(CO)4(nbd)] (4) (synthesis of 5) or [Mo(CO)6] (synthesis of 6) with FcN≡C (2) is discussed. IR studies confirm the formation of cis‐[Mo(CO)4(C≡NFc)2] (5) and mer‐[Mo(CO)3(C≡NFc)3] (6). The electrochemical behavior of 2, 3 a–c, 5 and 6 is reported. Compound 2 shows a reversible Fc redox event at E°1′=355 mV (ΔEp=60 mV). Upon complexation of 2 to M(CO)5 this wave is slightly shifted to E°′=335 (3 a), 345 (3 b) and 340 mV (3 c) showing that in 3 a–c the FcN≡C ligand is more easy to oxidize. The substitution of further CO ligands in 3 b by FcN≡C as characteristic for 5 and 6 influences the respective redox events insignificantly. Reversible oxidation of Cr occurs at 1045 mV (3 a) (ΔEp=60 mV), while for 3 b,c (3 b: 1170 mV, 3 c: 1290 mV) irreversible oxidations were observed. In addition, in situ spectroelectrochemical IR studies were carried out on 3 a–c. The results were further confirmed by DFT calculations.