Ligand isotope studies of Zeise's salt derivatives (and their CO analogues) with some aza-heterocycles and their N-oxides. II : Their preparation,characterisation, and use in developing 1H nmr and infrared spectra as a diagnostic tool

Forty-one π-acid complexes of the type cis-Pt(bipyO₂H)(A)X₂]X and trans-PtL(A)X₂] (A = C₂H₄, CO; X = Cl, Br; L = pyridazine {pdz}, pyrazine N-oxide {pzO}, quinoline {quin}, quinoline N-oxide {quinO}, 2,2′-bipyridine {bipy}, 1,10-phenanthroline {phen}) and their deuterated L and C₂D₄ analogues have been characterised employing infrared and ¹H nmr spectroscopy. The employment of v₁₂ (CH₂ scissors ∼1460 cm⁻¹) of η²-ethene as a diagnostic probe in distinguishing between 4- and 5-coordination is proposed, while the summed percentage decrease of v₂+v₃ (vC=C/δCH₂) may be used to distinguish between N- and O-coordination. The use of chemical shifts (¹H nmr spectroscopy) is confirmed as a suitable means to distinguish between 4- and 5-coordination and is also shown to be suitable for distinction between N- and O-coordination in four coordinate Pt(II) η²-ethene complexes. In contradiction of previous reports, it is found that J_Pt-H cannot be employed to determine the coordination number.