A long-standing structural puzzle resolved: the crystal structure of [Ag-2(Tp(Me,Me))(2)] [where Tp(Me,Me) is hydrotris(3,5-dimethyl-pyrazolyl)borate]

The crystal structure of the simple 1:1 complex of Ag(I) with hydrotris(3,5 -dimethylpyrazolyl)borate orate (Tp(Me,Me)) has been shown to be an asymmet ric dimer, in which each Tp(Me,Me) ligand bridges both metals by coordinati ng two pyrazolyl donors to one Ag(I) centre and one to the other, such that to a first approximation one Ag(I) is four coordinate and the other is two coordinate. However two of the pyrazolyl donors around the 'four-coordinat e' metal centres are also involved in weak, asymmetric bridging interaction s with the l'two coordinate' metal centres. This is in contrast to the stru cture of the Cu(I) analogue [Cu-2(Tp(Me,Me))(2)] in which both Cu(I) ions a re three coordinate. (C) 1999 Elsevier Science Ltd. All rights reserved.