Stuart R. Batten

Interpenetrating Nets: Ordered, Periodic Entanglement

Independent one-, two-, and even three-dimensional nets interpenetrate each other in many solid-state structures of polymeric, hydrogen-bonded nets and coordination polymers. For example, the interpenetration of the adamantane units of two diamondlike nets is shown on the right. A detailed and systematic examination of many interpenetrating nets of this kind is made, and implications for crystal engineering are discussed.

Structure and magnetism of coordination polymers containing dicyanamide and tricyanomethanide

Coordination polymers containing dicyanamide (N(CN)2−, dca) or tricyanomethanide (C(CN)3−, tcm) bridging ligands are described from the perspective of their structure and magnetism. The binary compounds α-M(dca)2 form an isostructural series (M=Cr, Mn, Fe, Co, Ni, Cu) having a single rutile-like network that involves μ1,3,5-dca bridging. They display quite diverse types of long-range magnetic order viz. canted-spin antiferromagnets (Cr, Mn, Fe), ferromagnets (Co, Ni, Cu). An up-to-date review is given of the diverse range of physical measurements made on the α-M(dca)2 series together with interpretations for the different net exchange coupling and consequent 3D order. The doubly interpenetrating rutile network M(tcm)2 series generally do not show long-range order except for a few members at very low temperatures. The ‘mixed’ self-penetrating network compounds M(dca)(tcm) do show long-range order (M=Co, Ni), albeit at lower Tc values than for the M(dca)2 parents. Modification of the M–dca networks is possible by incorporation of coligands into the structures. Ternary species of type M(dca)2(L)n, where L is a terminal (e.g. pyridine, MeOH) or a bridging (e.g. pyrazine, 4,4′-bipyridine) coligand, display a diverse range of 1D, 2D and 3D structural types. With a few exceptions, the large number of compounds structurally characterised contain μ1,5-dca bridging and display very weak antiferromagnetic coupling (J<ca. −1 cm−1), typical of this bridging mode. Compounds such as Mn(dca)2(pyrazine) display a magnetic phase transition at low temperatures. This is also the case in the isostructural 2D layer compounds M(dca)2(H2O) · phenazine (M=Fe, Ni) which, perhaps not surprisingly, do not have coordinated phenazines but, rather, phenazines intercalated between layers of M(dca)2(H2O) in which μ1,3,5 and μ1,5-dca bridging exists. Anionic networks of types M(dca)3− and M(dca)42− formed by templation around cations of the organic (e.g. Ph4E+, R4N+) or inorganic (M(2,2′-bipyridine)32+) types are described. The latter display no magnetic interactions between the weakly antiferromagnetically coupled anionic sub-lattice and the paramagnetic cationic sub-lattice.

Topology of interpenetration

Recent examples of interpenetrating and self-penetrating networks are highlighted in a discussion of interpenetration topology. A web site (http://web.chem.monash.edu.au/Department/Staff/Batten/Intptn.htm) has been set up which contains a tabulated list of all known examples of interpenetration.

Ni(tpt)(NO3)2—A Three-Dimensional Network with the Exceptional (12,3) Topology: A Self-Entangled Single Net

The shortest circuits in the three-dimensional network with (12,3) topology of solvated Ni(tpt)(NO3 )2 pass through one another (see picture). This network based upon interlinked double helices occupies a unique position in the set of (n,3) nets. tpt=tri-4-pyridyl-1,3,5-triazine.

Interdigitation, interpenetration and intercalation in layered cuprous tricyanomethanide derivatives

Reaction of Cu(I), tricyanomethanide (tcm , C(CN)3-) and L = either hexamethylenetetramine (hmt), 4,4-bipyridine (bipy) or 1,2-bis(4-pyridyl)ethene (bpe) gives crystals of [Cu(tcm)(hmt)] (1), [Cu(tcm)(bipy)] (2) and [Cu(tcm)(bpe)] x 0.25 bpe x 0.5 MeCN (3), respectively. Crystal structure analysis shows 1-3 all contain closely related puckered (4,4) sheets composed of tetrahedral Cu(I) ions bridged by 2-connecting tcm- and L. The crystal packing, however, varies markedly with L. In 1 the sheets interdigitate in pairs. In 2 the sheets participate in parallel interpenetration in pairs. In 3 guest bpe and MeCN molecules are intercalated in channels formed by the stacking of the sheets.

Ionic Liquids Based on Imidazolium and Pyrrolidinium Salts of the Tricyanomethanide Anion

A novel series of tricyanomethanide ionic liquids have been prepared and characterized for potential use as ionic liquid solvents. Full thermal analyses of all salts at ambient and sub-ambient temperatures are reported (melting points –17° to 160°C). The thermal stability and decomposition temperatures are also presented (Tdecomp ≈ 300°C). An electrochemical window of ~3 V has been established and the conductivity measured over a range of temperatures (20 mS cm–1 at 25°C).

An unprecedented eight-connected self-penetrating network based on pentanuclear zinc cluster building blocks

The first eight-connected self-penetrating metal-organic framework, based on pentanuclear zinc cluster building blocks, defines a new self-penetrating topology for eight-connected networks and represents the highest connected topology presently known for self-penetrating systems.

Lanthaballs: chiral, structurally layered polycarbonate tridecanuclear lanthanoid clusters.

New balls please! The viability of using carbonate as the primary anion in cluster formation is demonstrated in the synthesis of lanthaballs, spherical tridecanuclear lanthanoid complexes with a novel [Ln(CO(3))(6)] moiety in a [Ln(13)(CO(3))(14)] core (see picture). The chirality of the lanthaballs is evidenced in the configuration of extended columns of pi-stacked phenanthroline ligands. The structural and magnetic properties of lanthaballs are investigated.

Structure and magnetism of trinuclear and tetranuclear mixed valent manganese clusters from dicyanonitrosomethanide derived ligands

Abstract Two new mixed valent clusters of manganese have been synthesised in which the starting pseudochalcogenide ligand, dicyanonitrosomethanide, (ONC(CN) 2 xa0− , (dcnm − )) undergoes nucleophilic addition of methanol in complex 1 and water in complex 2 during coordination to the metal ions. Crystal structures show that complex 1 is a linear trinuclear Mn(II)Mn(III)Mn(II) compound, [Mn 3 (mcoe) 6 ]NO 3 ·2H 2 O, containing bridging oximate moieties from the chelating ligand methyl(2-cyano-2-hydroxyimino)ethanimidate ([ONC(CN)C(NH)OCH 3 ] − , mcoe − ). Compound 2 has a planar rhomboidal (butterfly) arrangement of Mn(II)Mn(III)Mn(II)Mn(III) with the Mn(III) ions in ‘body’ positions bridged to the ‘wingtip’, seven coordinate Mn(II) ions by μ 3 -oxo atoms and by the NO − oximato groups of the cyanoacetamidooximate chelating ligand, cao − , [ONue605C(CN)CONH 2 ] − . 2 has the formula (Me 4 N) 2 [Mn 4 O 2 (cao) 4 (MeCN) 2 (H 2 O) 6 ](NO 3 ) 4 ·2H 2 O. There are hydrogen bonded cluster–cluster interactions in both compounds. Detailed susceptibility and magnetisation measurements on 1 and 2 reveal intra-cluster antiferromagnetic coupling with a total spin ground state at the crossover point of S T =2 and 1 for 1 , with other states very close in energy, and a rare sixfold degenerate set of S T levels, 0,1,2,3,4,5, lying lowest in the case of 2 . In the latter case this is largely because of the large J 13 (Mn(III)Mn(III)); body–body) value (−46.0 cm −1 ) compared with the wing-body (Mn(II)Mn(III)) J 12 value of −2.5 cm −1 . These coupling constants and S T states are compared with those of other recent examples of planar rhomboidal mixed valent clusters, some of which show ferromagnetic J values and very large S T ground states, with single-molecule magnetic behaviour exhibited in those cases. AC susceptibility studies show that complex 2 does not exhibit single-molecule magnetism behaviour.

Syntheses, crystal structures, and magnetic properties of first row transition metal coordination polymers containing dicyanamide and 4,4′-bipyridine

The complexes of formulae M(dca)2(bipy) n(M = Fe 1, Co 2, Ni 3; dca = dicyanamide, N(CN)2−; bipy = 4,4′-bipyridine) and M(dca)2(bipy)(H2O)·0.5MeOH (M = Mn 4, Fe 5, Co 6), have been synthesized and characterized by single crystal and powder X-ray diffraction. Compounds 1–3 contain two interpenetrating 3D α-Po related networks. Bidentate dca ligands bridge the octahedral metal atoms to form square-grid like M(dca)2 sheets, with the bipyridine ligands linking these sheets together to form the α-Po-like 3D networks. The large amount of space within a single 3D network allows the interpenetration of the second 3D network. Compounds 4–6 contain 1D ‘tubes’ packing together in a parallel interdigitated fashion. Water ligands coordinated to the octahedral metal ions and intercalated methanol molecules occupy the inside of the M(dca)2 tubes while protruding monodentate bipyridine ligands participate in both π-stacking and hydrogen bonding interactions between adjacent tubes. Co(dca)2(bipy)·0.5H2O·0.5MeOH 7 and Cu(dca)2(bipy)·H2O 8 consist of inclined interpenetrating 2D sheets of M(dca)2(bipy), while Cu(dca)2(bipy)·MeOH 9 and Cu(dca)2(bipy)·2H2O 10 contain 2D zigzag sheets of Cu(dca)2(bipy) with parallel packing. Fe(dca)2(bipy)(H2O)2·(bipy) n11 contains 1D chains of Fe(bipy) with hydrogen bonding extending the topology to that of two 3D interpenetrating α-Po related networks. Compounds 7 and 11 contain octahedral metal ions, while 8 and 9 have five-coordinate Cu atoms. Variable temperature magnetic susceptibility studies (2–300 K; H n= 1 T) have shown that these framework compounds generally display very weak antiferromagnetic coupling because of the long bipy and μ1,5 bridging pathways. Consequently no long-range magnetic order occurs.