The Double-Infusion Technique

This method is appropriate for growing single crystals of compounds that have a medium or low solubility and cannot be recrystallized because of a disproportionation in the mother liquor. The reaction is not carried out in a gel medium (sodium metasilicate or an organic gel), as in the well-known gel technique 1 rather a saturated solution of the compound itself is used as reaction medium.2 Thus crystals of a compound AX can be grown by slowly and simultaneously adding a solution of a compound AY and a solution of a compound BX to a saturated solution of AX according to the reaction 

Of course, the solubilities of AY, BX, and BY have to be considerably larger than that of AX. As is shown in Fig. 1, the double-infusion crystallizer consists of a thermostated (filled with oil) Pyrex vessel containing the saturated solution and eventually some seed crystals mounted on a stirrer. The solutions AY and BX are introduced through glass capillary tubes by means of a micropump t 

RARE EARTH TRANSITION ELEMENT CYANIDES Ln[M(CN)6]nH20 

Prandtl and Mohr15 probably were the first to prepare rare earth hexacyanofer-rates Ln[Fe(CN)6] H20 in microcrystalline form. Some of these cyanides 

Whereas the double-infusion technique is adequate for the growth of hexacyano-ferrate (III) and hexacyanocobaltate(III) crystals the solubilities of the chromium (III) salts are so high that crystals can be obtained by crystallization from a saturated solution.7 

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