Contrasting connectivity of amidine and phosphaamidine (1,3-P,N) Cu(I) complexes

• Aprotic acetamidine ligands coordinate to Cu through solely the Nimine.
• A bulky phosphaamidine coordinates η1–P to Cu, leaving the Nimine basic site dangling.
• Less bulky phosphaamidines coordinate η2–P,N to Cu.

Aprotic acetamidine {Me2NC(Me)N(R)(CuBr)}2 {R = iPr (2a), Cy (2b), Ph (2c)} and neutral 1,3-P,N phosphaamidine copper bromide complexes {(CuBr)(Ph2PC(Ph)NPh)}4 (6a), {(CuBr)4(Ph2PC(Ph)NiPr)2}·{2CH2Cl2} (6b), (CuBr)4(iPr2PC(Ph)NPh)2} (7a) and {(CuBr)4(iPr2PC(Ph)NiPr)2} (7b) are prepared by direct combination of corresponding amidine and phosphaamidine with CuBr(DMS). X-ray crystallographic analysis of the acetamidine complexes reveal monodentate Nimine coordination to copper with significant degree of delocalization about the NCN framework and a relatively short Cu–Cu interaction of 2.5758(8) Å in 2c compared to (2.9801)(10) Å 2a. The phosphaamidine ligands are never η1–Nimine bound; instead they are η1–P bound in the cubane complex 6a or η2-bound in the step cluster complexes 6b, 7a and 7b.

Coordination geometries of uncharged and aprotic amidines and 1,3-(P,N) phosphaamidines on Cu(I) centers.Figure optionsDownload as PowerPoint slide