The reaction of four equivalents of phenyl or tert-butyl isocyanate with the pyridine-derived tetraamine 2,6-C3H3N[CMe(CH2NH2)2]2 in toluene gives high yields of the quadruply ureido substituted products 2,6-C5H3N[CMe(CH2R)2]2 [R = -NH(CO)NHPh and -NH(CO)NHtBu]. Full spectroscopic data for both compounds are given. A single crystal X-ray structure determination of the phenyl derivative reveals an intricate network of both intra- and intermolecular hydrogen bonds involving the C=O and both NH functionalities in all ureido groups.
The Mg2+ assisted synthesis of a pyridine-derived tetraalcohol ligand with an NO4 donor set is described. 2,6-Diethylpyridine reacts cleanly with aqueous formaldehyde solution in the presence of 1 equivalent of MgSO4 hydrate in a pressurised vessel to give the quadruply hydroxymethylated product 2,6 -C5H3N[CMe(CH2OH)2]2 (1) as a crystalline solid. Two alkali/alkaline earth metal perchlorate adducts of 1 have been structurally characterised, viz. [(1)2 • LiClC4] (6) and [(1)2 • Ba(ClO4)2 ] (7). The ligand adopts a bridging coordination mode in both 6 (distorted tetrahedral coordination of Li+) and 7 (square prismatic coordination of Ba2+). The further derivatization of 1 leads to the tetratosylate (2) and the tetraazide (3), both of which have been obtained in pure form for the first time. Reduction of 3 gives the pentaamine ligand 2,6-C5H3N[CMe(CH2NH2)2]2 (4), isolated as the tetrakis(hydrobromide) salt 4 • 4 HBr. The presence of four ammonio substituents and an unprotonated pyridine nitrogen atom in the solid state has been unequivocally established by an X-ray structural analysis.