Diphosphines as bridging ligands in polymeric and dimeric thione-S-ligated Ag(I) nitrate complexes

• Published in: Inorganica Chimica Acta 2004-07, Vol.357 (9), p.2677-2686
• Main Authors: Aslanidis, P, Cox, P.J, Divanidis, S, Karagiannidis, P
• Format: Article
• Language: English
• Subjects: 1,2-bis(diphenylphosphino)ethane; 1,4-bis(diphenylphosphino)butane; Crystal structures; Heterocyclic thiones; Silver(I) complexes
• ISSN: 0020-1693; 1873-3255
• DOI: 10.1016/j.ica.2004.03.013

The behavior of the diphos ligands, 1,2-bis(diphenylphosphino)ethane (dppe) and 1,4-bis(diphenylphosphino)butane (dppb), towards coordination of Ag(I) nitrate in the presence of several heterocyclic thione ligands has been investigated. Both diphosphines adopt the doubly bridging coordination mode, however two types of products has been obtained for the cationic, tetrahedrally coordinated metal, namely polymer in the case of the short bite dppe and quadruply bridged dimer for the longer chained dppb. The crystal structure of one representative for each of these two types have been characterized by X-ray crystallography. Reactions of silver(I) nitrate with equimolar amounts of the diphos ligands 1,4-bis(diphenylphosphino)butane (dppb) or 1,2-bis(diphenylphosphino)ethane (dppe) and some heterocyclic thiones (L) in acetonitrile/methanol solvent afforded mixed-ligand complexes, the nature of which was found to be strongly influenced by the backbone length of the diphosphine ligand. The longer chained diphos ligand formed a series of dinuclear complexes of the type [Ag(dppb)(L)] 2(NO 3) 2 with both the diphosphine and thione ligands acting as bridging ligands between the two four-coordinate pseudo-tetrahedrally coordinated metal centers. In the unique case of L=4-methyl-5-trifluoromethyl-4H-1,2,4-triazoline-3(2H)-thione (mftztH), the reaction proceeded under exclusion of the thione ligand from the coordination sphere and coordination of the nitrate anions instead, leading to the diphosphine-doubly bridged dimeric compound [Ag(dppb)(NO 3)] 2. On the other hand, the complexes produced when using the short bite 1,2-bis(diphenylphosphino)ethane (dppe) turned out to be diphosphine-bridged cationic polymers of the type [Ag(dppe)(L) 2] n (NO 3) n . The structures of one representative for each of the two aforementioned series of complex compounds, namely [Ag(dppb)(py2SH)] 2(NO 3) 2 · 2H 2O and [Ag(dppe)(pymtH) 2] n (NO 3) n , have been established by single-crystal X-ray diffraction.