New linked macrocyclic systems. Interaction of palladium(II) and platinum(II) with tri-linked N2S2-donor macrocycles and their single-ring analogues

Palladium(II) and platinum(II) complexes of ligands incorporating three lin ked, 16-membered, N2S2-donor macrocycles, together with their single-ring a nalogues have been synthesised. The former complexes are of the form [M3L]( PF6)(6) (where M = Pd or Pt, and L is a linked three-ring macrocyclic speci es incorporating a 1,3,5-'tribenzyl' or a phloroglucinol core). The X-ray s tructure determination of the single ring species [PdL](PF6)(2) (where L is a single N-benzylated derivative of the N2S2-donor macrocycle) showed that the palladium is coordinated to all four donor atoms of the macrocycle in a 'square planar' manner. The electrospray mass spectra of the tri-linked m etal-containing species show a series of multiply charged ions resulting fr om the loss of hexafluorophosphate counter ions and hydrogens, and correspo nding to [M - nPF(6)](n+) and [M - nPF(6) - mH]((n-m)+). Expansion of indiv idual charged peaks revealed the expected wide mass range resulting from th e presence of three metal ions, each of which possesses a number of isotope s. Spectrophotometric titrations confirm that 3 : 1 (metal : ligand) stoich iometries occur for the complexes of these tri-linked ligands in acetonitri le.