Platinum Complexes of 5,6-Dihydroacenaphtho[5,6-cd]-1,2-dichalcogenoles



Six bis(phosphane)platinum complexes bearing dichalcogen acenaphthene ligands have been prepared by metathesis from cis-[PtCl2(PR3)2] (R3 = Ph3, Ph2Me, PhMe2) and the dilithium salts of the parent 5,6-dihydroacenaphtho[5,6-cd]-1,2-dichalcogenoles (AcenapE2, L1 E = S, L2 E = Se). For their synthesis, the appropriate disulfide or diselenide species was treated with super hydride [LiBEt3H] to afford the dilithium salt by in situ reduction of the AcenapE2 E–E bond. Further reaction, by metathetical addition to the cis-platinum precursor afforded the respective platinum(II) complexes [Pt(5,6-AcenapE2)(PR3)2] (R3 = Ph3: E = S 1, Se 2; R3 = Ph2Me: E = S 3, Se 4; R3 = PhMe2: E = S 5, Se 6). All six complexes have been fully characterised, principally by multinuclear magnetic resonance spectroscopy, IR spectroscopy and MS. The selenium complexes 4 and 6 provide examples of AA′X spin systems, as displayed by their 31P{1H} NMR spectra. The X-ray structures of L1, L2, 1, 2, 5 and 6 were determined and, where appropriate, the platinum metal geometry, peri-atom displacement, splay angle magnitude, acenaphthene ring torsion angles and E···E interactions were analysed. The platinum atoms were found to adopt a distorted square-planar geometry in all four complexes, and the nature of the AcenapE2 ligand plays little part in the conformation of the substituents bound to the trivalent phosphorus atoms.