title: Group 11 complexes with the bis(3,5-dimethylpyrazol-1-yl)methane ligand. How secondary bonds can influence the coordination environment of Ag(I): the role of coordinated water in [Ag2(mu-L)2(OH2)2](OTf)2.
abstract: The complexation properties of the ligand bis(3,5-dimethylpyrazol-1-yl)methane (L) towards group 11 metals have been studied. The reaction in a 1 : 1 molar ratio with [Cu(NCMe)4]PF6 or Ag(OTf) complexes gives the mononuclear [CuL(NCMe)]PF6 (1), with crystallographic mirror symmetry, or dinuclear [Ag2(mu-L)2](OTf)2 (2) (OTf = trifluoromethanesulfonate) in which the ligand bridges both silver centres, an unprecedented mode of coordination for this type of ligands. Compound 2 crystallizes with two water molecules and forms a supramolecular structure through classical hydrogen bonding. The reaction in a 2 : 1 ratio affords in both cases the four-coordinated derivatives [ML2]X (M = Cu, X = PF6 (3); Ag, X = OTf 4). The treatment of [Ag(OTf)(PPh3)] with the ligand L gives [AgL(PPh3)]OTf (5). The gold(I) derivative [Au2(C6F5)2(mu-L)] (6) has also been obtained by reaction of L with two equivalents of [Au(C6F5)(tht)]. These complexes present a luminescent behaviour at low temperature; the emissions being mainly intraligand but enhanced after coordination of the metal. Compounds 1-4 have been characterized by X-ray crystallography. DFT studies showed that, in the silver complex 2, coordination of H2O to Ag in the binuclear complex is favoured by formation of a hydrogen-bonding network, involving the triflato anion, and releasing enough energy to allow distortion of the Ag2 framework.
authors.affiliation: Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade de Lisboa, 1749-016, Lisboa, Portugal.
authors.forename: Maria
authors.initials: M
authors.lastname: José Calhorda
authors.forename: Paulo J
authors.initials: PJ
authors.lastname: Costa
authors.forename: Olga
authors.initials: O
authors.lastname: Crespo
authors.forename: M Concepción
authors.initials: MC
authors.lastname: Gimeno
authors.forename: Peter G
authors.initials: PG
authors.lastname: Jones
authors.forename: Antonio
authors.initials: A
authors.lastname: Laguna
authors.forename: Mar
authors.initials: M
authors.lastname: Naranjo
authors.forename: Susana
authors.initials: S
authors.lastname: Quintal
authors.forename: Yu-Jun
authors.initials: YJ
authors.lastname: Shi
authors.forename: M Dolores
authors.initials: MD
authors.lastname: Villacampa