Crystallisation of flexible dipyridyl ligands with Cd(NO₃)₂·6H₂O or CdSO₄·6H₂O gives co-ordination networks of composition [Cd(NO₃)₂(Py₂CH₂)₂] 1 [Py₂CH₂ = 1,1-bis(4-pyridyl)methane]; [Cd₂(NO₃)₄(Py₂C₃H₆)₄(H₂O)] 2 [Py₂C₃H₆ = 1,3-bis(4-pyridyl)propane]; [Cd₂(SO₄)₂(Py₂C₃H₆)₃(H₂O)_2.7]·4.5H₂O 3; [Cd(NO₃)₂(Py₂C₄H₈)(H₂O)₂] 4 [Py₂C₄H₈ = 1,4-bis(4-pyridyl)butane]; [Cd₂(NO₃)₄(Py₂C₅H₁₀)₃(H₂O)] 5 [Py₂C₅H₁₀ = 1,5-bis(4-pyridyl)pentane] and [Cd(NO₃)₂(Py₂C₆H₁₂)₂] 6 [Py₂C₆H₁₂ = 1,6-bis(4-pyridyl)hexane]. The compounds were characterised by X-ray single crystal diffraction studies. In compounds 1, 2, 4 and 6 the cadmium ions are hexa-co-ordinate with a slightly distorted octahedral geometry. Compounds 3 and 5 both display examples of a less common hepta-co-ordinate cadmium ion geometry. Compounds 2, 3 and 6 exhibit novel modes of interpenetration.

The hydrothermal reaction of benzene-1,3,5-tricarboxylic acid (H₃BTC) with M^II (M = Mn, Co or Zn), tris(4-carboxyphenyl)phosphine oxide (H₃TPO) or cis-stilbene-4,4′-dicarboxylic acid (H₂SDA) with Co^II and 2,2′-bipyridyl (BIPY) gave 1-D co-ordination networks formulated as: [M(HBTC)(BIPY)(H₂O)] (M = Mn 1, Co 2, or Zn 3; [Co₃(BTC)₂(BIPY)₂(H₂O)₆]·4H₂O 4, [Co₃(TPO)₂(BIPY)₂(H₂O)₆]·xH₂O 5 and [Co(SDA)(BIPY)(H₂O)] 6. Structures 1 and 2 consist of double stranded chains of alternating HBTC dianions and dimeric units M^II–M^II linked by two µ-(1,1) bridging carboxylates. Magnetic properties of 1 and 2 indicate the presence of ferromagnetic exchange interactions within the dimers. Structures 4 and 5 consist of chains with a molecular ladder motif which are stacked creating large channels lined by hydrated cobalt(II) ions. The H₂O/D₂O solvent exchange in structure 5, studied by infrared spectroscopy and thermal gravimetric analysis–mass spectrometry, provides evidence for the porosity and zeolitic nature of the material.

Heteroaromatic precursors to nitrogen substituted derivatives of Koelsch’s free radical have been prepared by the condensation of 4,5-diazafluorene with a fluorenylidene or diazafluorenylidene. These compounds appear coloured and can exist in different tautomeric forms. An improved one pot synthesis of 4,5-diazafluorenone has been developed by the oxidative ring contraction of 1,10-phenanthroline with aqueous potassium permanganate. Aza derivatives of Koelsch’s free radical are easily generated by oxidation of the appropriate precursors with K₃Fe(CN)₆. Treatment of 9-[(9H-4,5-diazafluoren-9-ylidene)phenylmethyl]-9H-fluoren-9-yl radical with CuCl₂ in EtOH gives a brown precipitate of a 1∶1 radical–ligand complex.

Crystallisation of flexible dipyridyl ligands with either Zn(NO₃)₂·6H₂O or Zn(ClO₄)₂·6H₂O gave co-ordination networks of composition [Zn₃(OH)₃{(NC₅H₄)₂C₃H₆}₃][NO₃]₃·8.67H₂O 1 [(NC₅H₄)₂C₃H₆ = 1,3-bis(4-pyridyl)propane]; [Zn₂(OH){(NC₅H₄)₂C₄H₈}₃][ClO₄]₃·H₂O·EtOH 2 [(NC₅H₄)C₄H₈ = 1,4-bis(4-pyridyl)butane] and [Zn₂(OH){(NC₅H₄)₂C₇H₁₄}₄][ClO₄]₃·0.5H₂O 3 [(NC₅H₄)₂C₇H₁₄ = 1,7-bis(4-pyridyl)heptane]. The compounds were characterised by X-ray single crystal diffraction studies. Compound 1 possesses a trinuclear Zn₃(OH)₃ 6-membered ring that acts as a template for the co-ordination framework. Both 2 and 3 possess dinuclear zinc sub-units (Zn₂OH) that contain a bridging hydroxyl ion.