The contribution of powder diffraction methods to structural co-ordination chemistry

Ab-initio X-ray powder diffraction (see cover for typical spectra) is shown to be a powerful structural tool for (i) insoluble, thermally unstable, compounds which cannot be (re)crystallised from solution or from the melt; (ii) metastable phases destroyed or modified upon manipulation; (iii) twins; (iv) very small crystals and/or crystal aggregates; (v) gas/solid, liquid/solid and solid-state reactions fragmenting and misorienting the coherent domains of the starting crystals but conserving the (poly)crystalline nature of the sample.