화학공학소재연구정보센터
Inorganic Chemistry, Vol.46, No.8, 2979-2987, 2007
Trinuclear silver(I) complexes of fluorinated pyrazolates
Silver pyrazolates {[3-(CF3)Pz]Ag}(3), {[3-(CF3),5-(CH3)Pz]Ag}(3), {[3-(CF3),5-(Ph)Pz]Ag}(3), {[3-(CF3),5-(Bu-t)Pz]Ag}(3), and {[3-(C3F7),5-(Bu-t)Pz]Ag}(3) have been synthesized by treatment of the corresponding pyrazole with a slight molar excess of silver(I) oxide. This economical and convenient route gives silver pyrazolates in high (> 80%) yields. X-ray crystal structures of {[3-(CF3),5-(CH3)Pz]Ag}(3), {[3-(CF3),5-(Bu-t)Pz]Ag}(3), and {[3-(C3F7),5-(Bu-t)Pz]Ag}(3) show that these molecules have trinuclear structures with essentially planar to highly distorted Ag3N6 metallacycles. {[3-(CF3),5-(CH3)Pz]Ag}(3) forms extended columns via intertrimer argentophilic contacts (the closest Ag center dot center dot center dot Ag separation between the neighboring trimers are 3.355 and 3.426 angstrom). The trinuclear {[3-(CF3),5-(Bu-t)Pz]Ag}(3) units crystallize in pairs, basically forming "dimers of trimers", with the six silver atom core of the adjacent trimers adopting a chair conformation. However, in these dimers of trimers, even the shortest intertrimer Ag center dot center dot center dot Ag distance (3.480 angstrom) is slightly longer than the van der Waals contact of silver (3.44 angstrom). {[3-(C3F7),5-(Bu-t)Pz]Ag}(3), which has two bulky groups on each pyrazolyl ring, shows no close intertrimer Ag center dot center dot center dot Ag contacts (closest intertrimer Ag center dot center dot center dot Ag distance = 5.376 angstrom). The Ag-N bond distances and the intratrimer Ag center dot center dot center dot Ag separations of the silver pyrazolates do not show much variation. However, their N-Ag-N angles are sensitive to the nature (especially, the size) of substituents on the pyrazolyl rings. The pi-acidic {[3,5-(CF3)(2)Pz]Ag}(3) and {[3-(C3F7),5-(Bu-t)Pz]Ag}(3) form adducts with the pi-base toluene. X-ray data show that they adopt extended columnar structures of the type {[Ag-3](2)center dot[toluene]}(infinity) and {[Ag-3]'center dot[toluene]}(infinity) ({[3,5-(CF3)(2)Pz]Ag}(3) = [Ag-3],{[3-(C3F7),5-(Bu-t)Pz]Ag}(3) = [Ag-3]'), in which toluene interleaves and makes face-to-face contacts with {[3-(C3F7),5-(Bu-t)Pz]Ag}(3) or dimers of {[3,5-(CF3)(2)Pz]Ag}(3).