Coordination Networks Based on Tetrahedral Silane Building Blocks: Influence of the Anion on Structures Adopted by Ag+−Si(p-C6H4CN)4 Arrays

The silane tetrakis(4-cyanophenyl)silane ( 1 ) was prepared by the reaction of 4-lithiobenzonitrile with silicon tetrachloride at −100 °C. This tetrahedral molecular building block crystallizes with AgOTf (OTf = O 3 SCF 3 ) from benzene and dichloromethane to give [Ag 2 Si( p- C 6 H 4 CN) 4 ][OTf] 2 ·2C 6 H 6 ( 2 ). The extended solid structure of 2 is composed of interpenetrating “double layers” which are 3-connected via trigonal planar Ag and tetrahedral Si centers. The individual nets contain six-membered rings which are folded in one corner along a Si···Si vector to give an envelope conformation. Overall, the structure is heavily cross-linked via −CN−Ag(1)−NC−, −Ag(1)−Ag(2)−NC−, and −CN−Ag(2)(μ-O 3 SCF 3 ) 2 Ag(2)−NC− linkages. Compound 1 also crystallizes with AgPF 6, to give {Ag 3 [Si( p- C 6 H 4 CN) 4 ] 2 }[PF 6 ] 3 ·1.6THF·0.5C 6 H 6 ·CH 2 Cl 2 ( 3 ). This coordination network also contains 3-connected nets, with six-membered rings in the chair conformation. These nets are interwoven to form the 3-dimensional structure. Compounds 2 and 3 are air-sensitive, and their structures are readily broken up by dissolution in acetone. The network of 2 appears to lose crystallinity when exposed to heat and vacuum (by PXRD) but nonetheless retains some properties as a molecular sieve.