Six platinum bisphosphine complexes, bearing dichalcogen acenaphthene ligands, have been prepared by metathesis from cis-[PtCl 2 (PR 3 ) 2 ] (R 3 = Ph 3 , Ph 2 Me, PhMe 2 ) and the dilithium salts of the parent 5,6-dihydroacenaphtho[5,6-cd]-1,2-dichalcogenoles [AcenapE 2 ] (L1 E = S, L2 E = Se). For their synthesis, the appropriate disulfide or diselenide species was treated with super hydride [LiBEt 3 H] affording the dilithium salt by in situ reduction of the AcenapE 2 E-E bond. Further reaction, via metathetical addition to the cis-platinum precursor afforded the respective platinum(II) complex [Pt(5,6-AcenapE 2 )(PR 3 ) 2 ] (R 3 = Ph 3 : E = S 1, Se 2; R 3 = Ph 2 Me: E = S 3, Se 4; R 3 = PhMe 2 : E = S 5, Se 6).All six complexes have been fully characterised, principally by multinuclear magnetic resonance spectroscopy, IR and MS. Selenium complexes 4 and 6 provide examples of AA`X spin systems, as displayed by their 31 P{ 1 H} NMR spectra. X-ray structures were determined for L1, L2, 1, 2, 5 and 6 and analysed, where appropriate, by platinum metal geometry, periatom displacement, splay angle magnitude, acenaphthene ring torsion angles and E···E interactions. Platinum was found to adopt a distorted square-planar geometry in all four complexes, with the nature of the AcenapE 2 ligand playing little part in the conformation of the substituents bound to the trivalent phosphorus atoms.____________ [a] EASTChem, School of Chemistry, University of St Andrews, St Andrews, Fife, KY16 9ST, UK. Fax: (+44)1334 463384 E-mail: jdw3@st-and.ac.uk Supporting information for this article is available on the WWW under http://www.eurjic.org/ or from the author. IntroductionThe coordination chemistry of peri-substituted naphthalenes and structurally related systems has been developed over the last 15 years. [1] Geometric constraints unique to these frameworks are imposed by a double substitution at the peri-positions (positions 1 and 8 of the naphthalene ring, 5 and 6 of acenaphthene), [2,3] placing large heteroatoms or groups in close proximity, usually within van der Waals radii.[4] A number of investigators have utilised this characteristic of the naphthalene scaffold to study bonding interactions in main group systems, where molecular geometry is determined by a competition between attractive (covalent and weak) forces and repulsive interactions (steric strain). [5,6] The distinguishing feature of peri-substitution is the ability to achieve a relaxed geometry via formation of a direct bond between the two peri-atoms. [7] Furthermore, proximity effects associated with peri-substitution favours complexation to a bridging metal species, providing the correct spacial arrangement for bidentate coordination.Transition metal complexes incorporating 1,8-disubstituted naphthalene ligands have been well documented, [1] with the majority of examples reported bearing either bis(phosphine) or bis(thiolate) functionalities. Complexes assembled from ligands with Group 16 donor atoms invariably contain the naphthalene-1,8-dichalcogenol...

No abstract