Syntheses, Structures and Theoretical Investigations of 1λ4,3λ4,5λ4‐Trithia‐2,4,6,8,9‐pentaazabicyclo[3.3.1]nona‐1(9),2,3,5,7‐pentaenes

The syntheses of the title compounds RCN5S3 with electron‐withdrawing aryl substituents [R = 2‐FC6H4 (1m), 4‐FC6H4 (1n), 2,6‐F2C6H3 (1o), C6F5 (1p), 4‐NCC6H4 (1q) and Cl3C (1r)] are described. The X‐ray structures of 1n, 1o, 1q and 1r, together with those of Me2NCN5S3 (1b) and 4‐CH3C6H4CN5S3 (1f), are reported. The experimentally determined dependence of the bond lengths on the substituents R within the bicyclic system RCN5S3 is well‐reflected in the results of the theoretical calculations (RHF, MP2, B3LYP). The bonding model developed shows that acceptor substituents do not influence bonding within the bicycle. In the solid state, two fundamentally different primary interactions of the RCN5S3 molecules are observed; “stacking” and “dimerisation”, which can be rationalised by electrostatic interactions between the CN5S3 units. However, secondary effects − the interactions between the R substituents − may be even more dominant. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)