Synthesis of 5,5-Bicyclic Amidines as Ligands for Thermally Stable Vapor Deposition Precursors

We describe the syntheses of three fully aliphatic 5,5-bicyclic amidines. The syntheses are facile and scalable and can be easily modified to produce other 5,5-bicyclic amidine ligands with other substitution patterns. Treatment of one of the ligands with KHMDS and subsequent transmetalation with CuCl resulted in a dimeric copper­(I) bicyclic amidinate complex in 55% yield after recrystallization. This modestly air stable complex exhibits good volatility and thermal decomposition rates 1 order of magnitude lower than those of a similar, but acyclic, copper­(I) amidinate. Together, the ligands enable a general method for producing a library of thermally stable metal amidinate precursors with a wide variety of metals for use in vapor deposition.