Synthesis and Structural Characterization of a Bitopic Ferrocenyl-Linked Bis(pyrazolyl)methane Ligand and Its Silver(I) Coordination Polymers

The bitopic ligand 1,1‘-bis(dipyrazol-1-ylmethyl)ferrocene, Fe[C5H4CH(pz)2]2 (1; pz = pyrazolyl ring), has been prepared by the reaction of 1,1‘-ferrocenedicarbaldehyde and 1,1‘-carbonyldipyrazole. In the solid state, the bis(pyrazolyl)methane moieties are in an antiperiplanar eclipsed orientation. The molecules are organized into a three-dimensional array by π···π, weak C−H···N hydrogen bonding, and C−H···π interactions. The reactions between 1 and AgBF4, AgPF6, AgSO3CF3, or AgSbF6 yield {Fe[C5H4CH(pz)2]2AgBF4} n (2), {Fe[C5H4CH(pz)2]2AgPF6} n (3), {Fe[C5H4CH(pz)2]2AgSO3CF3} n (4), and {Fe[C5H4CH(pz)2]2AgSbF6} n (5), respectively. The solid-state structures consist of coordination polymers with compounds 2 and 3 arranged in helical chains, while the chains in 3·1/2Et2O, 4·1.5C6H6, 5·1/2Et2O, and 5·1/2C6H6 are nonhelical. In these structures, the ferrocenyl groups adopt a similar orientation, where the angle between CH(pz)2 groups is confined to the range of 85−99° and the silver pyrazolyl coordination spheres are also in very similar distorted-tetrahedral arrangements. Both structural types form three-dimensional supramolecular structures organized by weak hydrogen bonds, π···π stacking, and CH···π interactions. In the helical form, the anions reside in the pockets formed by the close-packed chains, whereas in the nonhelical form, sizable channels, which contain the solvent molecules and the anions, are located between the chains.