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 react ion of 4-lithiobenzonitrile with silicon tetrachloride at -100 degrees C. This tetrahedral molecular building block crystallizes with AgOTf (OTf = O3SCF3) from benzene and dichloromethane to give [Ag2Si(p-C6H4C N)(4)][OTf](2) .2C6H6 (2). The extended solid structure of 2 is compos ed of interpenetrating ''double layers'' which are 3-connected via tri gonal planar Ag and tetrahedral Si centers. The individual nets contai n six-membered rings which are folded in one corner along a Si ... Si vector to give an envelope conformation. Overall, the structure is hea vily cross-linked via -CN-Ag(1)-NC-, -Ag(1)-Ag(2)-NC-, and -CN-Ag(2)(m u-O3SCF3)(2)Ag(2)-NC-linkages. Compound 1 also crystallizes with AgPF6 , to give {Ag-3[Si(p-C6H4CN)(4)](2)}[PF6](3) . 1.6THF . 0.5C(6)H(6) . CH2Cl2 (3). This coordination network also contains 3-connected nets, with six-membered rings in the chair conformation. These nets are inte rwoven to form the 3-dimensional structure. Compounds 2 and 3 are air- sensitive, and their structures are readily broken up by dissolution i n 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.