Syntheses, structures and properties of two dinuclear mercury(II) iodide compounds containing tetradentate tripodal amine/pentadentate N-donor Schiff base: Control of molecular and crystalline architectures by varying ligand matrices.

Two dinuclear mercury(II) iodide complexes of the types [(L1)Hg( μ-I)HgI] ( 1) and [Hg(L2)(I)] ⋅ HO ( 2) [L1 = tris(2-aminoethyl)amine and L2 = N,N-( bis-(pyridin-2-yl)benzylidene)diethylenetriamine] have been synthesized and characterized using microanalytical, spectroscopic, thermal and other physicochemical results. Structures of both the compounds are solved by X-ray diffraction measurements. Structural analyses show that one mercury (II) centre in 1 adopts a distorted tetrahedral geometry with an HgI chromophore surrounded by four iodides, while the other has a distorted trigonal bipyramidal environment with an HgNI chromophore bound by four N atoms of L1 and one bridging iodide. Pentadentate Schiff base (L2) in 2 shows unusual binucleating bis(bidentate) behaviour to bind two different mercury(II) centres-Hg1 with an HgN I chromophore in a distorted square pyramidal geometry and Hg2 with an HgN I chromophore in a tetrahedral environment. Weak intermolecular N-H ⋅⋅⋅I hydrogen bonds in 1 and cooperative C-H ⋅⋅⋅ π and π⋅⋅⋅ π interactions in 2 promote dimensionalities. The Schiff base complex, 2, shows intraligand ( π- π*) fluorescence in DMF solution at room temperature, whereas compound 1 containing tripodal amine is fluorescent-inactive. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]