Tuning the coordination geometry of silver in bis(pyrazolyl)alkane complexes

Silver(l) 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(l) complexes, especially its ability to participate in cation ...pi interactions. The complex Ag[(PZ)(2)CPh2](2)}(PF6).C3H6O adopts an unusual square planar coordination environment as indicated by the sum of the four N-Ag-N angles being 360degrees. 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(l)...pi arene interactions but rather of the constraints imposed by the steric crowding caused by (aryl)(2)C(PZ)(2) ligands. In contrast, the complexes of the other two ligands, {Ag[(PZ)(2)CHPh](2)](PF6).0,5CH(2)Cl(2) and {Ag[(pz)(2)CH(CH2Ph)](2)}(PF6).CH2Cl2, show normal tetrahedral geometry about the silver(l), also with no indication of silver(l) (...) pi arene interactions. All three new complexes have extended supramolecular structures supported by a combination of CH...T and CH...F interactions.