Interplay between the Supramolecular Motifs of Polypyridyl Metal Complexes and Halogen Bond Networks in Cocrystals

Abstract

Combining [Ni­(phen)3]­I2 or [Ni­(phen)3]­Cl2 (phen = 1,10-phenanthroline) with the iodoperfluorobenzenes (IPFBs), 1,2-, 1,3-, 1,4-diiodotetrafluorobenzene (1,2-, 1,3-, and 1,4-DITFB, respectively), or 1,3,5-triiodotrifluorobenzene (1,3,5-TITFB) resulted in the formation of six different cocrystalline materials featuring halogen-bonded networks encapsulating [Ni­(phen)3]2+ ions. The cocrystals have the general formula [Ni­(phen)3]­[(IPFB) n (X2)­(L) m ]·solvate (n = 2 or 3; X = Cl– or I–; L = halogen-bonded H2O and/or MeOH; solvate = isolated H2O and/or MeOH). The halide ions balance the charge of the metal complexes and simultaneously act as halogen bond acceptors for the electronically polarized iodine atoms of the IPFB donors. The structures display a wide variety of supramolecular motifs in the context of both the aggregation of the metal complexes and the topology and connectivity of the halogen bond networks. The well-known supramolecular “aryl embrace” motifs of [Ni­(phen)3] complexes are present but are structurally compromised to varying degrees in the crystals of [Ni­(phen)3]­[(1,2-DITFB)2I2]·MeOH, [Ni­(phen)3]­[(1,3-DITFB)2I2]·2MeOH, and [Ni­(phen)3]­[(1,3-DITFB)2(H2O)2Cl2]·1.5MeOH. In [Ni­(phen)3]­[(1,3-DITFB)3I2], the [Ni­(phen3]2+ complexes are so thoroughly enclosed in halogen-bonded networks that the metal complexes have no significant supramolecular contact. In contrast, in [Ni­(phen)3]­[(1,4-DITFB)3I2(MeOH)0.5] and [Ni­(phen)3]­[(1,3,5-TITFB)2Cl2] the complexes are arranged in typical aryl embrace motifs (pairwise and 1D chains, respectively), but with adjacent complexes held in closer proximity to each other than they reside in crystals of the pure metal complex. The interplay between the supramolecular chemistry of the halogen-bonded networks and the metal complexes was examined in detail, and the results demonstrate that it is possible to significantly influence the aggregation of metal complexes by encapsulation in different halogen bond networks.

The Influence of Liquid on the Outcome of Halogen-Bonded Metal–Organic Materials Synthesis by Liquid Assisted Grinding

“…Layers are further connected into a 3D network via C-H···C and C···C contacts (Figure 5d). The described charge-assisted halogen bond supramolecular motif has been recognized in earlier studies [50][51][52]. However, even thoguh halide (Cl − , Br − , I − ) anions are potent halogen bond acceptors, a survey of the CSD based on 14tfib cocrystals with the I···X − motif has resulted in only 26 hits.…”

Mechanochemical Preparations of Anion Coordinated Architectures Based on 3‐Iodoethynylpyridine and 3‐Iodoethynylbenzoic Acid

“…Halogen bonding has become an important interaction for anion coordination (C−I⋅⋅⋅X; X=Cl − , Br − , I − ), offering directional scaffolding for crystal engineering. Several crystal structures have been reported featuring anions coordinated by halogen bond donors, such as 1,4‐diiodotetrafluorobenzene and 1,3,5‐tri(iodoethynyl)‐2,4,6‐trifluorobenzene . This C−I⋅⋅⋅X − motif has been shown to be of use in several classes of functional materials, such as in halide recognition and rotaxanes .…”

Cobaloximes as Building Blocks in Halogen-Bonded Cocrystals

“…As introducing metal atoms into a supramolecular material can significantly expand the possibilities of adding and controlling additional properties (such as magnetism and conductivity) [28,29], the use of halogen bonding in the crystal engineering of metal-organic materials has been an attractive challenge over the past decade [30][31][32][33][34][35][36][37][38][39][40]. While there have been substantial studies into halogen bonding in single component metal-organic solids [30][31][32][33][34][35][36][37][38][39][40][41], synthesis of multi-component materials based on halogen-bonded metal-organic components has been receiving much less attention. Particularly scarce are studies involving cocrystals of neutral metal-organic components acting as halogen bond acceptors [42][43][44][45][46][47].…”