Halogenocuprate ions three-coordinated metal centers

Dinuclear anions, halogenocuprate(I) and halo-genoargentate(I) ions four-coordinated metal centers, 37 20-21 three-coordinated metal centers, 37 8-9, 12-16... 

Discrete trinuclear halogenocuprate(I) or halogenoargentate(I) species containing solely three-coordinated metal centers have not been reported hitherto. An [Ag3I6]3 ion in which one of the silver(I) atoms is three coordinated, whereas the remaining two exhibit tetrahedral coordination geometry has, however, recently been isolated (81) (cf Section II,C,3). 

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