Low-Dimensional Architectures in Isomeric cis-PtCl₂{Ph₂PCH₂N(Ar)CH₂PPh₂} Complexes Using Regioselective-N(Aryl)-Group Manipulation

The solid-state behaviour of two series of isomeric, phenol-substituted, aminomethylphosphines, as the free ligands and bound to Pt^II, have been extensively studied using single crystal X-ray crystallography. In the first library, isomeric diphosphines of the type Ph₂PCH₂N(Ar)CH₂PPh₂ [1a-e; Ar = C₆H₃(Me)(OH)] and, in the second library, amide-functionalised, isomeric ligands Ph₂PCH₂N{CH₂C(O)NH(Ar)}CH₂PPh₂ [2a-e; Ar = C₆H₃(Me)(OH)], were synthesised by reaction of Ph₂PCH₂OH and the appropriate amine in CH₃OH, and isolated as colourless solids or oils in good yield. The non-methyl, substituted diphosphines Ph₂PCH₂N{CH₂C(O)NH(Ar)}CH₂PPh₂ [2f, Ar = 3-C₆H₄(OH); 2g, Ar = 4-C₆H₄(OH)] and Ph₂PCH₂N(Ar)CH₂PPh₂ [3, Ar = 3-C₆H₄(OH)] were also prepared for comparative purposes. Reactions of 1a-e, 2a-g, or 3 with PtCl₂(η⁴-cod) afforded the corresponding square-planar complexes 4a-e, 5a-g, and 6 in good to high isolated yields. All new compounds were characterised using a range of spectroscopic (¹H, ³¹P{¹H}, FT-IR) and analytical techniques. Single crystal X-ray structures have been determined for 1a, 1b∙CH₃OH, 2f∙CH₃OH, 2g, 3, 4b∙(CH₃)₂SO, 4c∙CHCl₃, 4d∙½Et₂O, 4e∙½CHCl₃∙½CH₃OH, 5a∙½Et₂O, 5b, 5c∙¼H₂O, 5d∙Et₂O, and 6∙(CH₃)₂SO. The free phenolic group in 1b∙CH₃OH, 2f∙CH₃OH_,2g, 4b∙(CH₃)₂SO, 5a∙½Et₂O, 5c∙¼H₂O, and 6∙(CH₃)₂SO exhibits various intra- or intermolecular O-H∙∙∙X (X = O, N, P, Cl) hydrogen contacts leading to different packing arrangements.