Pyridine—halogen complexes, dissociation

Pyridine-halogen complexes (73) dissociate on heating halogen is lost so readily that these compounds act as mild halogenating agents toward phenol or aniline, for example (see Section 3.2.1.3.8). 

Tertiary arsines, phosphines, and stibines can also be displaced from their CuX(ZPh3)3 or Cu2X2(Z Ph3)3 (Z = As, P Z = As, P, Sb X = halogen) complexes by pyridine and related amines to give CuX(ZPh3)(amine) complexes. The structures of these are uncertain since their dissociation or decomposition in solution makes molecular weight data unreliable (176, 178). 

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