Co-ordination chemistry of 1,4,7-triazacyclononane (L) and its N-methylated derivative (L′) with silver(I) and mercury(II). The crystal structures of [AgL′2]PF6 and [AgL′(SCN)]

Reaction of AgPF6 in acetonitrile with an equimolar amount of the macrocycle 1,4,7-triazacyclononane (L) and addition of [NBu4]X (X = Cl, Br, I or CN) affords colourless to yellow precipitates of [AgL(X)]. The complexes [AgL′(X)](X = SCN or CN)(L′= 1,4,7-trimethyl-1,4,7-triazacyclononane) have been prepared similarly. When the ligand to AgPF6 ratio was 2:1 in ethanolic solution, colourless crystals of [AgL2]PF6 and [AgL′2]PF6 were obtained, respectively. A binuclear species [LAg(µ-CN)AgL]PF6 has been obtained from a solution of AgPF6 and L (1:1) in pyridine upon addition of NaCN (0.5 equivalent). Mercury(II) chloride reacts in water with L (1:2) and addition of NaPF6 to yield [HgL2][PF6]2; with L′ the complex [HgL′(Cl)]PF6 was obtained. Crystals of [AgL′2]PF6 are tetragonal, space group P42/m(no. 84), with a= 10.134(1), c= 12.771(2)A, and Z= 2. Crystals of [AgL′(SCN)] are orthorhombic, space group Pcmn(no. 62), with a= 9.497(5), b= 11.837(8), c= 26.00(1)A and Z= 8.