Metal complexes of 2,6-bis[(pyrazol-1-yl)methyllpyridine: The search for aryl-pyrazolyl embrace interactions as a synthon for crystal engineering

The 2,6-py(CH2-pz)(2) ligand was used to prepare metal complexes as follows: [py(CH(2)pz)(2)](BiI3), {Ag[py(CH(2)pz)(2)](OTf)center dot CH3CN}(infinity), {PtCl[py(CH(2)pz)(2)](2)}(BF4), {Cd[py(CH(2)pz)(2)](2)}(BF4)(2)center dot[4,4'-bipyl-0.5H(2)O, and {Cd[phen](3)}(2)(BF4)(4)center dot[py(CH(2)pz)(2)]center dot 5H(2)O (py = pyridyl, pz = pyrazolyl, and phen = 1,10-phenanthroline). The solid state structures of each complex show that all five compounds are organized by noncovalent forces into complex extended structures. Each structure has a common supramolecular organizational feature between the ligands of a cooperative offset face-to-face pi-pi stacking and C-H center dot center dot center dot pi interaction formed from both the pyridyl and the pyrazolyl rings that is termed the aryl-pyrazolyl embrace. The systematic analysis of this synthon showed that the pi-pi stacking component of the aryl-pyrazolyl embrace always involves rings of the same type.