Organometallic polymorphism and phase transitions

The possibility of obtaining the same organometallic substance in different crystal forms, which may or may not interconvert via a phase transition, is reviewed. The occurrence of reversible order-to-order and order-to-disorder phase transitions, usually associated with reorientational processes in the solid state for mono- and poly-nuclear organometallic complexes, is addressed. Pseudo-polymorphism arising from co-crystallisation of solvent molecules and the preparation and interconversion of pseudo-polymorphs by non-solution methods are discussed.