Synthetic and structural studies of heteroleptic platinum(ii) complexes containing crown trithioether and diphosphine ligands

Abstract

We wish to report the syntheses and spectroscopic properties of seven new Pt(II) heteroleptic complexes containing a series of diphosphine [P2 = Ph₂PCH₂CH₂PPh₂ (dppe), Ph₂P(CH₂)₃PPh₂ (dppp), Ph₂P(CH₂)₄PPh₂ (dppb), Ph₂P(CH₂)₅PPh₂ (dpppe), 1,2-Ph₂PC₆H₄PPh₂ (dppbe), and 1,2-Ph₂C₂H₂PPh₂ (dppv)] ligands and the crown trithioethers [9]aneS₃ (1,4,7-trithiacyclononane) or [10]aneS₃ (1,4,7-trithiacyclodecane). All seven reported complexes have the general formula [Pt([n]aneS₃)(P2)](PF₆)₂ and form similar structures in which the Pt(II) center is surrounded by a cis arrangement of the two P donors from the diphosphine chelate and two sulfur atoms from the trithioether ligand. The third sulfur atom forms a longer interaction with the platinum resulting in an elongated square pyramidal structure with Pt–S axial distances ranging from 2.6505(9) to 2.8766(17) Å. The ¹⁹⁵Pt NMR chemical shifts for the complexes show values in the range of −4400 to −4700 ppm, consistent with a cis-PtS₂P₂ coordination sphere.