Multiple anion...π interactions in tris(1,10-phenanthroline-κ²N,N′)iron(II) bis[1,1,3,3-tetracyano-2-(2-hydroxyethyl)propenide] monohydrate

Abstract

In the ionic structure of the title compound, [Fe(C12H8N2)3](C9H5N4O2)2·H2O, the octahedral tris-chelate [Fe(phen)3](2+) dications [Fe-N = 1.9647 (14)-1.9769 (14) Å; phen is 1,10-phenathroline] afford one-dimensional chains by a series of slipped π-π stacking interactions [centroid-to-centroid distances = 3.792 (3) and 3.939 (3) Å]. The 1,1,3,3-tetracyano-2-(2-hydroxyethyl)propenide anions, denoted tcnoetOH(-), reveal an appreciable delocalization of π-electron density, involving the central propenide [C-C = 1.383 (3)-1.401 (2) Å] fragment and four nitrile groups, and this is also supported by density functional theory (DFT) calculations at the B97D/6-311+G(2d,2p) level. Primary noncovalent inter-moiety interactions comprise conventional O-H...O(N) and weak C-H...O(N) hydrogen bonding [O...O(N) = 2.833 (2)-3.289 (5) Å and C...O(N) = 3.132 (2)-3.439 (2) Å]. The double anion...π interaction involving a nitrile group of tcnoetOH(-) and two cis-positioned pyridine rings (`π-pocket') of [Fe(phen)3](2+) [N...centroid = 3.212 (2) and 3.418 (2) Å] suggest the relevance of anion...π stackings for charge-diffuse polycyanoanions and common M-chelate species.

Tris(2,2′-bipyridine)iron(II) bis(1,1,3,3-tetracyano-2-ethoxypropenide) dihydrate: chiral hydrogen-bonded frameworks interpenetrate in three dimensions

“…The shorter C-CN bonds and the longer C-N bonds involving atoms C411 and C412 are associated with the strong and nearly linear O-HÁ Á ÁN hydrogen bonds which have atoms N411 and N412 as the acceptors (Table 3); by contrast, the N atoms at the other end of the anion, atoms N431 and N432, are involved only in the weaker C-HÁ Á ÁN hydrogen bonds. As usually observed in anions of this type (Setifi, Domasevitch et al, 2013;, 2014Setifi, Lehchili et al, 2014), the two -C(CN) 2 units in the anion of compound (I) are rotated, in conrotatory fashion, out of the plane of the central propenide fragment. The dihedral angles between the central C 3 unit and the -C(CN) 2 units based on atoms C41 and C43 are 13.9 (4) and 26.1 (3) , respectively.…”

“…In this respect, (I) may be contrasted with the structure of monohydrate (III) (Setifi, Domasevitch et al, 2013) (see Scheme 1), where the anion contains a 2-hydroxyethoxy substituent rather than the simple ethoxy substituent found in compounds (I) and (II) [although (III) was inadvertently named in the original report as a 2-hydroxyethyl derivative]. In the structure of compound (III), multiple -stacking interactions links the cations into chains, along which cations of Á and à configurations alternate; however, significant -stacking interactions are absent from the structure of compound (II).…”

“…Both strong interactions between metal centres and rigid supramolecular structures are required to achieve highly co-operative SCO systems, and both hydrogen bonds and -interactions are among the intermolecular interactions most commonly used for the construction of rigid systems (Halcrow, 2011), the potential significance of anionÁ Á Á interactions for SCO systems has recently been reported and evaluated (Quesada et al, 2008;Kitchen et al, 2009). Thus, the use of new families of polynitrile ligands with a tris-chelate complex cation is a particularly attractive way to better understand the role of noncovalent anionÁ Á Á interactions for the development and synthesis of SCO materials (Ellingsworth et al, 2013;Setifi, Domasevitch et al, 2013). In a further exploration of low-spin iron(II) complexes offering the potential for this type of anionÁ Á Á interaction, we now report the synthesis and structure of the title compound, [Fe(bipy) 3 ](tcnoet) 2 Á2H 2 O, (I), where bipy represents 2,2 0 -bipyridine and tcnoet À represents the 1,1,3,3-tetracyano-2-ethoxypropenide anion, and we compare the structure of (I) with those of related 1,10-phenanthroline complexes (II) and (III) (Setifi, Domasevitch et al, 2013) (see Scheme 1).…”

“…Thus, the use of new families of polynitrile ligands with a tris-chelate complex cation is a particularly attractive way to better understand the role of noncovalent anionÁ Á Á interactions for the development and synthesis of SCO materials (Ellingsworth et al, 2013;Setifi, Domasevitch et al, 2013). In a further exploration of low-spin iron(II) complexes offering the potential for this type of anionÁ Á Á interaction, we now report the synthesis and structure of the title compound, [Fe(bipy) 3 ](tcnoet) 2 Á2H 2 O, (I), where bipy represents 2,2 0 -bipyridine and tcnoet À represents the 1,1,3,3-tetracyano-2-ethoxypropenide anion, and we compare the structure of (I) with those of related 1,10-phenanthroline complexes (II) and (III) (Setifi, Domasevitch et al, 2013) (see Scheme 1). Computer programs: APEX2 (Bruker, 2009), SAINT (Bruker, 2009), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009).…”

Bis[tris(pyridin-2-yl)amine]iron(II) tris(dicyanomethylidene)methanediide

“…The presence of other potential donor groups such as those derived from -OH, -SH or -NH 2 , together with their rigidity and electronic delocalization, mean that polynitrile anions can also lead to new bistable materials (Benmansour et al, 2010;Setifi et al, 2009Setifi et al, , 2014Pittala et al, 2017). As a part of our continuing study of the structural and magnetic properties of iron(II) complexes containing both polynitrile and polypyridyl units (Setifi et al, 2013(Setifi et al, , 2017(Setifi et al, , 2018a, we data reports report here the molecular and supramolecular structure of a new compound based on tri(2-pyridyl)amine (tpa) as ligand and the tris(dicyanomethylene)methanediide dianion (tcpd 2À ) as the counter-ion.…”