Syntheses, molecular and crystalline architectures, and luminescence behaviour of terephthalate bridged heptacoordinated dinuclear lead(II) complexes containing a pentadentate N-donor Schiff base.

One-pot synthesis using a 2:2:1:2 molar ratio of Pb(OAc)·3HO, L, piperidinum terephthalate (ptp) and NaClO/NHPF at room temperature affords two dinuclear compounds of the type [Pb(L) $_{2}(\upmu $-tp)](ClO/PF) ( 1/2) [L=N,N-(bis-(pyridin-2-yl)benzylidene)diethylenetriamine and tp = terephthalate dianion]. The compounds are characterized by microanalytical, spectroscopic, thermal and other physicochemical results. X-ray structural analyses of 1 and 2 reveal that each heptacoordinated lead(II) centre with a PbNO chromophore are bound by five N atoms of L and connected through O atoms of a bis(bidentate) tp bridge. The arrangements of L and tp suggest a gap around the metal centre due to occupation of a stereo-active lone pair of electrons reflecting a hemidirected coordination around the metal centre. The complexes exhibit reasonable thermal stabilities with the tolerate temperatures ca. 255°C for 1 and 263°C for 2. The complexes display intraligand ( π- π*) fluorescence in the solid state and in DMF solutions at room temperature. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]