From Mono- to Polynuclear Coordination Complexes with a 2,2?-Bipyrimidine-4,4?-dicarboxylate Ligand

The coordination properties of the ligand 2,2'-bipyrimidine-4,4'-dicarboxylic acid (H2bpd) with lanthanide(III) ions (Ln = Eu, Tb, or Lu) were investigated. syntheses H2bpd and its salts, [K2(bpd)(H2O)2] (1) [(AlkNH)Lu(bpd)2] (Alk Et, Hex, en), are described. In presence LnCl3 salts Lu, Tb), formation [Ln(bpd)2]- [Ln(bpd)(H2O)x]+ species was assessed by 1H nuclear magnetic resonance (NMR), spectrophotometry, spectrofluorometric titrations in aqueous solution. solid state structure 1, [K(H2O)2][Lu(bpd)2] (2), [(Et3NH)Lu(bpd)2] (3) could be determined X-ray diffraction, showing to act as a tetradentate unit three five-membered chelate rings around central Ln(III). With aim building polynuclear assemblies, between [Lu(bdp)2]- [Lu(tta)3(H2O)] units (tta thenoyltrifluoroacetylacetonate) also methanol, NMR titration experiments revealed complex mixtures from which two new identified, [Lu2(bpd)(tta)4] (4) H[Lu(bpd)(tta)2] (5), confirmed their analysis. Using highly lipophilic cations chloroform, octametallic [enH]4[Lu8(bpd)4(tta)18] (6) isolated determined.