Influence of the substituent R1 on the reactivity of [(η5-C5H5)Fe{(η5-C5H4)–CHN–(R1)–OH}] {R1 = –CH2–CH2– or 1,2-C6H4} with platinum(ii) and on the properties of the complexes

Abstract

The synthesis and characterization of four different types of platinum(II) complexes derived from [(η⁵-C₅H₅)Fe{(η⁵-C₅H₄)–CHN–(CH₂–CH₂–OH)}] (1b) are reported. The new products are the trans- and cis-isomers of [Pt{(η⁵-C₅H₅)Fe[(η⁵-C₅H₄)–CHN–(CH₂–CH₂–OH)]}Cl₂(dmso)] {trans-(2b) and cis-(3b)} and the platinacycles [Pt{[(η⁵-C₅H₃)–CHN–(CH₂–CH₂–OH)]Fe(η⁵-C₅H₅)}Cl(L)] {with L = dmso (4b) or PPh₃ (5b)} or [Pt{[(η⁵-C₅H₃)–CHN–(CH₂–CH₂–O)]Fe(η⁵-C₅H₅)}(L)] {with L = PPh₃ (6b) or dmso (7b)}. In these products 1b acts as a (N) donor ligand (in 2b and 3b), as a bidentate [C(sp², ferrocene), N]⁻ (in 4b and 5b) or as a terdentate [C(sp², ferrocene), N, O]^2– ligand (in 6b and 7b). The crystal structures of 4b and 5b confirm the mode of binding of the ferrocenylaldimine (1b) and a trans-arrangement between the neutral ligand (L) and the imine nitrogen. Comparative studies of: (a) the reactivity of ligands [(η⁵-C₅H₅)Fe{(η⁵-C₅H₄)–CHN–(R¹)–OH}] {R¹ = –CH₂–CH₂– or 1,2-C₆H₄} with cis-[PtCl₂(dmso)₂] and (b) the properties of their platinum(II) complexes are also reported and provide conclusive evidence of the influence of the nature of the R¹ group of [(η⁵-C₅H₅)Fe{(η⁵-C₅H₄)–CHN–(R¹)–OH}] on: (a) the spectroscopic and electrochemical properties of these ligands and their platinum(II) complexes, (b) the cycloplatination process, and (c) the ease with which the mode of binding of the ligand changes from bidentate [C(sp², ferrocene), N]⁻ to terdentate [C(sp², ferrocene), N, O]^2– or vice versa.