Explorations in Oxazoline Chemistry: Transition metal Complexes of 2-Acylmethyl-2-Oxazoline Ligands and Novel Thionated and Selenated Derivatives

A series of six oxazoline proligands (the Tohda oxazolines) have been used to synthesize a series of novel κ²-(N,O)-oxazoline metal complexes of V, Mn, Zn, Cd, and Hg, with characterization by NMR spectroscopy, HR-MS and X-ray crystallography, and testing of catalytic ability for V and Mn complexes. Additionally, the Tohda oxazolines underwent thionation by Lawesson’s reagent to yield six stable thioketones (2a-f), while the analogous selenation by Woollins’ reagent gave a selenazolidine in a low yield. Use of P4S10 under the same conditions resulted in chelation of an S=P=S unit to give the first-known dithioxophospharane oxazolines. Finally, thioketone derivative 2a was used to synthesize thiolate complexes with transition metals of groups 9, 10, 11 and 12, and post-transition metals Tl and Pb. These were compared structurally and catalytically to their acyl analogues with only complex Ni-2a showing definite activity as a catalyst, albeit at a lower performance in styrene polymerization than its acyl counterpart.