Tuning the Coordination Geometry of Silver in Bis(pyrazolyl)alkane Complexes

Silver(I) complexes of the bis(pyrazolyl)methane ligands Ph2C(pz)2, PhCH(pz)2, and PhCH2CH(pz)2 (pz = pyrazolyl
ring) have been prepared in an attempt to explore how sterically hindered poly(pyrazolyl)methane ligands influence
the variable coordination geometries exhibited by silver(I) complexes, especially its ability to participate in
cation···π interactions. The complex {Ag[(pz)2CPh2]2}(PF6)·C3H6O adopts an unusual square planar coordination
environment as indicated by the sum of the four N−Ag−N angles being 360°. The proximity of phenyl groups
above and below the AgN4 core enforces the unusual coordination geometry about the metal center. This arrangement
is not a result of silver(I)···π arene interactions but rather of the constraints imposed by the steric crowding caused
by (aryl)2C(pz)2 ligands. In contrast, the complexes of the other two ligands, {Ag[(pz)2CHPh]2}(PF6)·0.5CH2Cl2 and
{Ag[(pz)2CH(CH2Ph)]2}(PF6)·CH2Cl2, show normal tetrahedral geometry about the silver(I), also with no indication
of silver(I)···π arene interactions. All three new complexes have extended supramolecular structures supported by
a combination of CH···π and CH···F interactions.