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-(But)Pz]Ag}3,
and {[3-(C3F7),5-(But)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-(But)Pz]Ag}3, and {[3-(C3F7),5-(But)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···Ag separation between the neighboring trimers are 3.355 and 3.426 Å). The trinuclear {[3-(CF3),5-(But)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···Ag
distance (3.480 Å) is slightly longer than the van der Waals contact of silver (3.44 Å). {[3-(C3F7),5-(But)Pz]Ag}3,
which has two bulky groups on each pyrazolyl ring, shows no close intertrimer Ag···Ag contacts (closest intertrimer
Ag···Ag distance = 5.376 Å). The Ag−N bond distances and the intratrimer Ag···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 π-acidic {[3,5-(CF3)2Pz]Ag}3 and {[3-(C3F7),5-(But)Pz]Ag}3 form
adducts with the π-base toluene. X-ray data show that they adopt extended columnar structures of the type
{[Ag3]2·[toluene]}∞ and {[Ag3]‘·[toluene]}∞ ({[3,5-(CF3)2Pz]Ag}3 = [Ag3],{[3-(C3F7),5-(But)Pz]Ag}3 = [Ag3]‘), in
which toluene interleaves and makes face-to-face contacts with {[3-(C3F7),5-(But)Pz]Ag}3 or dimers of {[3,5-(CF3)2Pz]Ag}3.