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[C 5 H 4 CH(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 AgBF 4, AgPF 6, AgSO 3 CF 3, or AgSbF 6 yield {Fe[C 5 H 4 CH(pz) 2 ] 2 AgBF 4 } n ( 2 ), {Fe[C 5 H 4 CH(pz) 2 ] 2 AgPF 6 } n ( 3 ), {Fe[C 5 H 4 CH(pz) 2 ] 2 AgSO 3 CF 3 } n ( 4 ), and {Fe[C 5 H 4 CH(pz) 2 ] 2 AgSbF 6 } 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 / 2 Et 2 O, 4 ·1.5C 6 H 6, 5 · 1 / 2 Et 2 O, and 5 · 1 / 2 C 6 H 6 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.