C3 symmetric tris(phosphonate)-1,3,5-triazine ligand: homopolymetallic complexes and its radical anionTo the memory of Pascal Le Floch (1958-2010).Electronic supplementary information (ESI) available: X-ray structures and spin distribution calculations on the radical anion. CCDC reference numbers 765555-765558. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c0nj00204f

The ligand 2,4,6-tris(dimethoxyphosphonate)-1,3,5-triazine L has been synthesized and its single crystal X-ray structure determined. The occurrence of P&z.dbd;O π intermolecular interactions, suggested by the short P&z.dbd;O triazine distances of 3.16-3.35 Å, is observed. The electrochemical reduction of the ligand shows its electron acceptor character by the formation of a stable radical anion. The hyperfine structure observed in the EPR spectra, combined with a theoretical DFT study, evidences the full delocalization of the unpaired electron mainly on the triazine core, with some participation of the phosphonate groups. Theoretical calculations are in agreement with the experimental values of the hyperfine coupling constants of 11.81 G for A iso - 31 P and 1.85 G for A iso - 14 N. Homopolymetallic complexes, formulated as { L [Cu(hfac) 2 ] 3 } ( 1 ), 1 ∞ { L 2 [Co(hfac) 2 ] 3 } ( 2 ) and 1 ∞ { L 2 [Mn(hfac) 2 ] 3 } ( 3 ) (hfac = hexafluoroacetylacetonate), have been synthesized and structurally characterized. The ligand 2,4,6-tris(dimethoxyphosphonate)-1,3,5-triazine L , for which EPR investigations and theoretical calculations have been performed on its radical anion, provided paramagnetic homopolymetallic complexes, which were structurally characterized.