Thionylimide and related systems

Abstract

While the synthesis of organic thionylimino (NSO) compounds has been known for over 140 years the synthesis of inorganic species was much less known and only really begun in the 1970s. The previous syntheses for these inorganic species were often complicated and involved highly reactive species. The goal of this work was to simplify the synthesis of transition metal complexes and main group compounds containing the thionylimide anion. An existing literature synthesis was improved and developed in to a new method using a solution of thionyl chloride in tetrahydrofuran and liquid ammonia. This led to significant yield increases over previous syntheses and in a much more efficient “one-pot” reaction. The scope of the reaction was investigated and complexes and compounds containing titanium, zirconium, hafnium, platinum, copper, zinc and antimony were synthesised. The first examples of antimony(V) and copper thionylimino compounds and complexes were prepared. The series of group IV metal complexes Cp₂Ti(NSO)₂, Cp*₂M(NSO)₂ (M = Ti, Zr and Hf) was synthesised. Cp*₂M(NSO)₂ (M = Ti and Hf) are novel complexes. These complexes along with the other thionylimino compounds and complexes formed the basis of an examination of the bonding properties of the thionylimino group in inorganic compounds. The reactivity of these species was examined and led to the isolation of a transition metal complex of the [N(SO₃)₂]³⁻ anion in the complex (2,2’- bipyridyl)₃Cu₂Cl(N(SO₃)₂). This was the first transition metal complex of this anion to be examined by single crystal X-ray crystallography. The reactivity of Cp₂Ti(NSO)₂ under various conditions was examined. It was discovered that Cp₂Ti(NSO)₂ could act as a metalloligand which contains bridging thionylimino groups. These species were shown to bridge via the nitrogen atom of the thionylimino groups. A series of metal complexes containing; copper, molybdenum, cobalt, mercury, and silver were synthesised. The electrochemistry of Cp₂Ti(NSO)₂, the neutral copper complexes and the molybdenum complex was examined in detail. The synthesis of various five-membered sulfur-nitrogen rings containing phosphorus, antimony, titanium and selenium was attempted. The synthesis of the five-membered selenium nitrogen species nBu₂SnSe₂N₂ was also attempted and gave promising preliminary results.