MULTINUCLEAR MAGNETIC RESONANCE STUDY OF GROUP 14-SUBSTITUTED SULFUR DIIMIDES, AND THE MOLECULAR STRUCTURES OF DI-tert-BUTYL-, BIS(TRIPHENYLSILYL)- AND N-TRIMETHYLSILYL-N′-TRIPHENYLSILYL SULFUR DIIMIDE

Abstract

Abstract Sulfur diimides of the type R(NSN)R′ (1–19, 2a–9a, 12a–17a, 20a, 3b–16b, 20b) were investigated by 15N, 29Si and 119Sn NMR at variable temperature in order to determine their preferred configuration (E/Z, Z/E, E/E or Z/Z) in solution. All sulfur diimides studied are highly fluxional at room temperature. In some cases with N′Bu groups, the presence of two isomers could be demonstrated. In solution, the E position is preferred for a silyl group, as shown, e.g., for N-tert-butyl-N′-trimethylsilyl sulfur diimide (2a). In the case of one germyl group, there is little preference of either E or Z position, whereas stannyl groups prefer to be in Z position. The situation in solution may differ considerably from the configurations determined in the solid state. Single crystal X-ray analyses were carried out for di-tert-butyl- (1), bis(triphenylsilyl)- (7) and N-trimethylsilyl-N′-triphenylsilylsulfur diimide (7b). All three molecules adopt the Z/E configuration in the crystal. Solid-state 29Si CP/MAS NMR s...