Preparation and characterization of the 1:1 adducts of mercury(II) halides with N-benzyl- and N-p-tolyl-2-oxo-1-naphthylideneamine.: The crystal and molecular structures of two isostructural di-μ-halo-bis[halo(N-benzyl-2-oxo-1-naphthylideneamine)- mercury(II)] adducts (halo = chloro, bromo)

A series of adducts of the type HgX2(C18H15NO) [X = Cl-, Br-, I-; C18H15NO = N-benzyl-2-oxo-1-naphthyfideneamine (bznapH), N-p-tolyl-2-oxo-1-naphthylideneamine (tolnapH)] was obtained by refluxing the solution of the corresponding mercury(II) salt and the related naphthylideneamine in absolute ethanol in a 1:1 molar ratio. The adducts di-mu -chloro-bis[chloro(N-benzyl-2-oxo-1-naphthylideneamine)mercury(II)], HgCl2(bznapH) (1) and di-mu -bromo-bis[bromo(N-benzyl-2-oxo-1-naphthylideneamine)mercury(ID], HgBr2(bznapH) (2) are isostructural. with the effective coordination of mercury being 2 + 2. The HgX2 moieties are retained in the adducts and contain two covalently linked chlorine [2.321(3) and 2.299(3) A in 1] or bromine atoms [2.446(1) and 2.422(1) Angstrom in 2]. These moieties are linked mutually by additional contacts of bridging halogen atoms [Hg . . . muX 3.189(2) and 3.298(1) Angstrom in 1 and 2, respectively], forming non-planar dimeric Hg2X4 units.. Each Schiff-base ligand has a strong contact with mercury through the oxygen atom [Hg . . .O 2.392(5) and 2.410(5) Angstrom in 1 and 2, respectively]. The Schiff-base ligand in 1 and 2 exists as the ketoamino (quinoid) tautomeric structure with an intramolecular hydrogen bond of the N-H . . .O type [2.58(1) and 2.59(1) Angstrom in 1 and 2, respectively]. On the contrary, in DMSO solution, due to dissociation of adducts 1-6, the enolimino (benzenoid) tautomeric form of the Schiff bases was established by NMR spectroscopy. (C) 2001 Elsevier Science B.V. All rights reserved.