Metal-perchlorate bonding

Coordination of perchlorate to transition and nontransition metal ions has been well established, though in most of the cases the metal-perchlorate bond is rather weak and has been termed as semicoordination (1). The coordination that can be recognized in the solid state may frequently break down in solution, particularly in aqueous medium (the solvent molecule replacing the coordinated perchlorate). 

Fig. 2. Types of metal-perchlorate bonding (a) monodentate (b) chelating bidentate (c) bridging bidentate.

One example of a seven-coordinate complex (158) involving three coordinated bidentatenaphthyridines and one perchlorate bonded to the metal through one of its oxygen atoms has also been prepared.91... 

Hexacarbonylmolybdenum forms a dicationic complex 392 with 2,4,6-triphenylthiopyrylium perchlorate. The sulfur atom appears to make no contribution to the metal-ring bonding and the heterocyclic rings are nonaromatic and nonplanar (Equation 100) <1999JOM(584)171>. 

At low temperatures phosphine reacts with perchloric acid to produce crystals of phosphonium perchlorate, PH CIO4, which are explosive and very sensitive to heat, moisture and friction. Phosphine readily forms addition complexes in which a metal-phosphorus bond is present, for example, H3P AICI3, H3P TiCl4, (H3P) Cr(CO)3 and HjP Co(NO)(CO)2 (Chapter 8.11). Borane complexes are also formed (Chapter 9.1). 

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