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.