Relationships between basicity, redox behaviour of ferrocenylamines and their reactivity with Pt[II] compounds

Abstract

p K b values for the ferrocenylamines, [( η-C 5H 4(CH 2) x NH 2)FeCp] x= 1, 2, 3; [( η-C 5H 4CH 2NHR)FeCp] R=Me, 4, Ph, 5; {[ η-C 5H 4CHR′NR 2]FeCp} R′/R=H/Me, 6, R′/R=H/Ph, 7, Me/Me, 8;[{ η-C 5H 4CHRNMe 2) 2Fe] R=H 9, Me 10; [{1,2 η-C 5H 3(CH 2NMe 2)(PPh 2)}FeCp] 11, {1,2 η-C 5H 3[CH(Me)NMe 2](PR 2}}Fe[ η-C 5H 4(PPh 2) n] n=0, R= i Pr 12, Ph 13, n=1, R=Me 14, are correlated with inductive, neighbouring group and steric effects. Corresponding salts have been synthesised. The p K b has a marked influence on their chemistry. Protonation competes with complexation but cis-PtCl 2L 2 L= 1– 3, 5, 7, and cis-Pt(N–N)Cl 2 L= 8, 9, have been characterised. Two reversible couples [Fc +A/FcA], [Fc +AH +/FcAH +] (A=amine function) and an irreversible oxidation/protonation of A are linked by a EECE mechanism, but potentials for the first two are independent of the amine and similar to ferrocene. Nucleophilic attack by ferrocenylamines at the nitrile, protonation and ligand substitution are all observed with cis-[PtCl 2(NCR) 2].