A remarkable accidental degeneracy in the1H-n.m.r. Spectrum of a (cyanoethene)platinum (II) complex

Summary In the¹H-n.m.r. spectra of (acetylacetonato)chloro-(²-cyanoetheiie)platinum(II), the three protons of the ligand appear to be equivalent.¹³C-n.m.r., i.r. and further¹H-n.m.r. studies indicate that the metal-ligand bonding is of orthodox -olefin type (as formulated in the name of the compound above). The two 2-hydrogens are made equivalent by fluxion, but there is an accidental degeneracy with 1-hydrogen atom.