Wan-Sheung Li

Inorganic crystal engineering using self-assembly of tailored building-blocks

Abstract The use of transition metal complexes of bridging bidentate ligands to construct predictable, multi-dimensional infinite networks is an area of chemistry which has received ever-increasing attention over recent years. This article will review the advances that have been made in this field of research and will illustrate how ligand design and the properties of the transition metal and counter-anion can be used to control network geometry and thus crystal structure. The range of network topologies and structural motifs that have been constructed thus far will be outlined with particular emphasis upon how specific arrays can be prepared via rational design of molecular building-blocks. The unusual phenomenon of interpenetration, or polycatenation, will be discussed and methods to achieve control over this effect will be highlighted.

Template self-assembly of polyiodide networks

A range of metal thioether macrocyclic complexes has been used as templating agents in the preparation of extended multi-dimensional polyiodide arrays. A selection of unusual and intriguing polyiodides is described, and the role played by the size, shape and charge of the metal macrocyclic complex discussed.

Template Assembly of Metal Aggregates by Imino‐Carboxylate Ligands

Lanthanide, main group, and transition metal ion templates provide different polynuclear cages from [M(L)] (M=Ni, Mn; (L)2−=CH2[CH2N=C(CH3)COO−]2). Templating with lanthanum results in a 12-coordinate LaIII ion encapsulated by six [Ni(L)] units, whereas with sodium four Na+ ions are trapped inside a tricapped trigonal prismatic [{Ni(L)}9] cage. With manganese, an octahedrally coordinated MnII ion is surrounded by six [Mn(L)] fragments in a twisted trigonal-prismatic configuration (see picture).

Synthesis and structure of tetranuclear zinc(II) and binuclear copper(II) complexes of a dithiolate compartmental macrocyclic ligand: a model for the binuclear CuA site in cytochrome c oxidase and N2O reductase

The tetranuclear cluster [Zn2L(µ-OH)]2[ClO4]2·2H2O (L = dianion of the condensation product of 1,3-diaminopropane and 2,6-diformyl-4-methylthiophenol) shows two unique dinuclear ZnII units linked by two µ-hydroxy bridges; the structure of the CuII complex [Cu2L(HOMe)2](NO3)]PF6 shows square-pyramidal coordination at the Cu centres with two thiolate bridges and two terminal N-donors, with a Cu⋯Cu separation of 3.264(2)A.

In situ ligand synthesis and construction of an unprecedented three-dimensional array with silver(i): a new approach to inorganic crystal engineering

Reaction of 1,2-trans-(4-pyridyl)ethene with AgBF 4 results in the formation of a three-dimensional network based upon a cyclobutane-linked tetrapyridyl ligand, 1,2,3,4-tetrakis(4-pyridyl)cyclobutane, linked by Ag I ions; the in situ formation of the ligand represents a potential new direction for inorganic crystal engineering.

Control of interpenetrating copper(i) adamantoid networks:synthesis and structure of{[Cu(bpe)2]BF4}n

Lengthening of linking bipyridyl ligands in interlocking copper(I)-heterocycle adamantoid arrays increases the volume of the adamantoid cages and consequently the number of observed interpenetrating networks: factors influencing the observed structures of these interpenetrating complexes are described in the context of the structure of {[Cu-(bpe) 2 ]BF 4 } n [bpe = 1,2-trans-(4-pyridyl)ethene].

Silver(I)–3,6-bis(pyridin-3-yl)-1,2,4,5-tetrazine coordination polymers: a diversity of chain motifs

Abstract The influence of solvent and anion on the formation of coordination polymers between silver(I) and 3,6-bis(pyridin-3-yl)-1,2,4,5-tetrazine (3,3′-pytz), a bridging ligand that can adopt both cisoid and transoidconformations, is reported. Reaction of AgPF6 in MeCN with 3,3′-pytz in CH2Cl2 gives ([{Ag(NCMe)2}(μ-3,3′-pytz)][PF6]·MeCN)∞, 1, of AgPF6 in MeNO2 and 3,3′-pytz in CH2Cl2 gives ([{Ag2(μ-3,3′-pytz)2}(μ-3,3′-pytz)][PF6]2·4MeNO2)∞, 2, and of AgCF3SO3 in MeCN and 3,3′-pytz in CH2Cl2 gives {[Ag(μ-3,3′-pytz)]CF3SO3}∞, 3. These cationic coordination polymers exclusively form chain structural motifs. That in 1, ([{Ag(NCMe)2}(μ-3,3′-pytz)]+)∞, has a castellated construction with each tetrahedral silver(I) center coordinated by two solvent molecules as well as two linking transoid-oriented 3,3′-pytz bridges (Ag⋯Ag 13.210 A) in a 1:1 polymeric chain. That in 2, ([{Ag2(μ-3,3′-pytz)2}(μ-3,3′-pytz)]2+)∞, is novel. It is the first coordination polymer to exhibit both cisoid and transoid conformations of a bridging ligand coordinated to the same metal center. Pairs of silver(I) centers are linked by pairs of cisoid-oriented 3,3′-pytz molecules (Ag⋯Ag = 11.695 A) to form [Ag2(μ-3,3′-pytz)2] motifs, which are bridged, in turn, by transoid-oriented 3,3′-pytz molecules (Ag⋯Ag = 13.318 A) to form a 3:2 ligand:metal infinite polymeric zigzag chain. That in 3, {[Ag(μ-3,3′-pytz)]+}∞, has a zigzag architecture despite being based on linear silver(I) centers. Transoid-oriented 3,3′-pytz molecules link silver(I) centers (Ag⋯Ag 13.225 A) to give a 1:1 ligand:metal infinite polymeric zigzag chain. The chains aggregate in parallel pairs linked by weak Ag⋯Ag contacts (Ag⋯Ag = 3.220 A), which are supported by (μ2-κO,κO′) bridging CF3SO3− anions.

Rectangular grid two-dimensional sheets of copper(II) bridgedby both co-ordinated and hydrogen bonded 4,4′-bipyridine(4,4′-bipy) in[Cu(µ-4,4′-bipy)(H2O)2(FBF3)2]·4,4′-bipy

The complex [Cu(µ-4,4′-bipy)(H 2 O) 2 (FBF 3 ) 2 ]·4,4′-bipy (4,4′-bipy = 4,4′-bipyridine), in which copper atoms are linked by Cu–4,4′-bipy–Cu and Cu–OH 2 ··· 4,4′-bipy ··· H 2 O–Cu assemblies, involving co-ordinated and hydrogen bonded 4,4′-bipy, respectively, to form two-dimensional rectangular grid sheets, has been isolated and structurally characterised.

Crystal engineering: the effects of π–π interactions incopper(i) and silver(i) complexes of 2,7-diazapyrene

The ligand 2,7-diazapyrene (L) is used to construct three- and two-dimensional arrays with Cu I and Ag I ions: {[Cu I L 2 ]PF 6 } ∞ shows an adamantoid network with three interpenetrating networks, while {[Ag I L 2 (MeCN) 2 ]BF 4 } ∞ forms linear chains of [AgL] ∞ units linked by apparent π–π stacking and Ag···Ag interactions between adjacent diazapyrene ligands to form two-dimensional sheets.

Polycatenated copper(I) molecular ladders: a new structural motif in inorganic coordination polymers

The complex {[Cu2(MeCN)2L3](PF6)2}∞ [L = 1,4-bis(4-pyridyl)butadiyne] is prepared and characterised by X-ray diffraction studies which show an undulating polycatenated molecular ladder structure involving fully interwoven two-dimensional sheets.