The NC H2CH3 region of the1H-n.m.r. spectrum of trans-PtCl2(π-C2H4)(NHEt2) has been investigated and shown to contain inequivalent protons. A study has also been made in related amine complexes of the conditions under which Pt-N-C H2 protons are equivalent, N H-C H coupling takes place and195Pt-N-C H coupling occurs. The lability of the N-H bond in trans-olefin-amine, carbonyl-amine, ethanide-amine and phosphine-amine complexes is also investigated and compared with that of the platinum-amine link. Trans-labilizing powers of π-C2H4, CO, CH2-CH2 and Ph3P are compared. © 1979 Verlag Chemie, GmbH.