ELSEVIER Inorgamca Chimrca Acta 282 I 1998) 237-242 Synthesis and structure of ( 1,34met complexes with aromatic nit Felix Zamora ‘** , Michel Sabat “, Bernhard Lippert” .’ Fuchhereich Chentie. Unirmiror Domntutd, D-41221 Dunmund. Germany hDrpartme~tt of Chenr~srty,. UniverGp of Krgintu. Chorlortesvrile. VA 22901. USA Received 20 March 1998: received in revised form II April 1998: accepted 15 May 1998 Abstract Reactions of ( I .3-dimethyluracil-5-yl ) mercury ( II Iacetate with the heterocycles I .8-naphthyridine ( napy ) and 2.2’-bipyridyl (bpy) yieB0 compounds of general composition [ Hg( I.3-DimeU-0) ( heterocycle) ] - Two examples. [ Hg( I.3-Dim&-C’S) ( napy 1I ( N&J -&O ( 1.1 and { Hg( I .3-DimeU-CS) (bpy ) 1 ( CIO,) (4) were crystallized and studied by X-ray crystallography and NMR spectroscopy. ‘H NMR data on the one hand and X-ray data on the other reveal differences in the mode of coordination for napy mercury complexes in water and in the solid state. While both napy and bpy act as chelating ligands in solution, napy behaves as a monodentate ligand in the solid state. Q 1998 Elseviel. Science S.A. All rights reserved. Ke~rrw&: Crystal structures: Mercury complexes: Nucleobase complexes 1. Introduction Mercury( II) shows a strong tendency towards linearcoor- dination geometry in organometallic compounds [ I]. Thus. methylmercury (II) nucleobase complexes, for instance, are almost entirely restricted to linear geometry [ 21. However, occasionally MeHg( II) complexes with bidentate and triden- tate ligands have been obtained in which Hg(I1) adopts higher coordination numbers. Examples include complexes with a series of 2,2’-bipyridyl (bpy ) [ 31, 1, lo-phenanthro- line ligands [4], N-substituted pyrazoles [ 51, and tripod ligands containing pyridine and N-metbylimidazole 161. Three- and four-coordination for MeHg( II ) has also been seen in several amino acid complexes [ 71. in fact, compari- sons of structural data of the [ HgMe( bpy ) ] ( NOz) complex and of amino acid complexes of MeHg(II) reveal that a similar sp-hybridization bonding model is applicable for the latter complexes [ 71. Furthermore, it has been found that the coordination geometry of Hg( II) with these ligands may be different in the solid state and in solution [ 31. We have previously analyzed by X-ray diffraction several examples containing the ( 1,3-DimeU-CS)Hg( II) moiety * Corresponding author. Present address: Deparrarnento de Quimica Inor- griaica. Facultad de Ciencias. Univenidad Autbnoma de Madrid, 28049 Madrid. Spain. Tel.: +34-l-397 3962; fax: +34-l-397 4833: e-mail: felix.zamora@uam.es; ( 1.3-DimeU = 1.3~dimethyluracil) [8-l l]- Only in one spe- cial case have we found a non-linear geometry. However, in that compound unusual Hg-Hg interactions were observed [ 111. Moreover, the rare imino tautomer of &nine was found in the compound [ Hg( 1.3~Dim&-CS) @-MeA- N6) ] NO3 - H1O. In this compJex, despite the presence of an Hg-N7 (A) distance of 2.87 A, the folding angle at Hg rules out any substanttal Hg-N7 bonding, suggesting that thecoor- dination geometry of Hg is essentially linear [ lo]. Following our recent interest in the chemistry of Hg( II) bioorganometallic complexes [8-I I]. the purpose of present study was to find out whether the ( I,3-Dim&- C5)Hgf II) moiety could adopt a non-linear geometry with ligands capable of binding a metal both in a monodentate and a bidentate fashion. 2. Exp-hnental 2. I. Preparation 2.1.1. Starting compounds The starting materials fHg(OAc)( l,ZDimeU-CS)] [8] and l,&naphthyridine ( napy) [ 121 were prepared as described previously. 1,3-Dimethyluracil and 2,2’-bipyridyl were purchased from Sigma. All of the perchlorate s&s of 0020-1693/98/$ - see front matter 0 1998 Elsevier Science S.A. All rights resewed. PIISOO20-1693(98)00236-9