“…[24][25][26] Methylation at the 6′ and 8 positions of the anchoring ligand may act as a protecting scaffold for the copper(I) metal center. In this respect, stereochemical protection can be potentially offered by the benzo ring of the quinoline moiety, as was reported for [Cu( R DAB dipp ) (L COOMe )][PF 6 ] ( R DAB dipp = 1,4-diaza-1,3-butadienes, R = H, Me; dipp = 2,6-diisopropylphenyl; L COOMe = methyl-2-( pyridin-2-yl)quinoline-4-carboxylate) complexes, 27 and for the case of a number of ruthenium(II) complexes. 15,28,29 Accordingly, simple organic diimine ligand precursors, analogues of pqca, substituted with methyl at the 6′ (6′-Mepqca), the 8 (8-Mepqca), and both the 8 and 6′ positions (8,6′-Me 2 pqca) of the pyridyl ring and the quinoline moiety, constitute the basis of this work.…”