Six tris(bipyridyl)iron(II) complexes with 2-substituted 1,1,3,3-tetracyanopropenide, perchlorate and tetrafluoridoborate anions; order versus disorder, hydrogen bonding and C - N⋯π interactions

Abstract

Structures are reported for six closely related salts of tris(bipyridyl)iron(II) cations, namely tris(2,2′-bipyridine)iron(II) bis(1,1,3,3-tetracyano-2-methoxypropenide) 0.776-hydrate, [Fe(C10H8N2)3](C8H3N4O)2.0.776H2O, (I), tris(2,2′-bipyridine)iron(II) 1,1,3,3-tetracyano-2-(propylsulfanyl)propenide perchlorate, [Fe(C10H8N2)3](C10H7N4S)(ClO4), (II), tris(5,5′-dimethyl-2,2′-bipyridine)iron(II) 1,1,3,3-tetracyano-2-methoxypropenide tetrafluoridoborate ethanol 0.926-solvate, [Fe(C12H12N2)3](C8H3N4O)(BF4).0.926C2H2O, (III), tris(5,5′-dimethyl-2,2′-bipyridine)iron(II) 1,1,3,3-tetracyano-2-ethoxypropenide tetrafluoridoborate, [Fe(C12H12N2)3](C9H5N4O)(BF4), (IV), tris(5,5′-dimethyl-2,2′-bipyridine)iron(II) 1,1,3,3-tetracyano-2-(ethylsufanyl)propenide tetrafluoridoborate, [Fe(C12H12N2)3](C9H5N4S)(BF4), (V), and tris(5,5′-dimethyl-2,2′-bipyridine)iron(II) 1,1,3,3-tetracyano-2-propoxypropenide tetrafluoridoborate, [Fe(C12H12N2)3](C10H7N4O)(BF4), (VI). In compound (I), one of the anions is disordered over two sets of atomic sites with equal occupancies while, in the second anion, just one of the C(CN)2 units is disordered, again over two sets of atomic sites with equal occupancies: the anionic components are linked by multiple C - H⋯N hydrogen bonds to form a three-dimensional framework. In compound (II), the polynitrile anion is disordered over two sets of atomic sites with occupancies in the approximate ratio 3:1, while the perchlorate anion is disordered over three sets of atomic sites: there are C - N⋯π interactions between the cations and the polynitrile anion. The polynitrile anion in compound (III) is fully ordered, but the tetrafluoridoborate anion is disordered over two sets of atomic sites with occupancies 0.671 (4) and 0.329 (4): the cations and the tetrafluoridoborate anions are linked by C - H⋯F interactions to form an interrupted chain. Compounds (IV) and (V) are isostructural and all of the ionic components are fully ordered in both of them: the cations and tetrafluoridoborate anions are linked into C22(12) chains. The polynitrile anion in compound (VI) is disordered over two sets of atomic sites with approximately equal occupancies, and here the chains formed by the cations and the tetrafluoridoborate anions are of the C22(13) type.