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Polyamino‐Substituted 1‐Oxa‐3,5‐diazahexatrienes and 1‐Oxa‐3,5,7‐triazaoctatetraenes (N‐Acyl‐oligocyanamides): Synthesis, Structures, Cyclovoltammetry and NLO Properties − Experiment and Theory

“…N(5)ϪC (6) and N(7)ϪC(8) are now longer (1.369 and 1.331 Å ), whereas C(6)ϪN (7) is shorter (1.339 Å ) indicating significant electronic delocalization in the sense of a 2-azaallyl cation submoiety in this part of the molecule. [20] The helix-type structure is not completely realized in the complex, since the torsion angle N(3)ϪC(4)ϪN (5)ϪC (6) is widened from Ϫ35.7°in 10d to Ϫ139.4°giving rise to a turn of the chain away from the chelate ring.…”

1:1- and 2:1-Copper(II) Complexes From PrimaryN-Acylamidines

“…Complexation at the oxygen atom and nitrogen atom N(5) (crystallographic numbering) of neutral 1a by the copper ion leads to the six-membered chelate ring of metal complex 2 One of chlorides is also located in the plane; the other chloride, however, is positioned far below the plane (see Figure 1), resulting in a strongly tetrahedrally deformed square planar coordination geometry around copper(II) (sum of angles: 364.29°). Coordination bond lengths are 1.932 (2) to N, 2.205(2) to O and 2.217(1) and 2.279(1) Å to chlorine. The NϪCuϪO bond angle amounts to 85.35°.…”

“…Interestingly, the OϪCuϪO and NϪCuϪN units are now in a trans arrangement, forming the planar copper(II) complex with centric symmetry. The CuϪN [1.905 (2)] and CuϪO bonds [1.917(2) Å ] are rather similar in length; compared to the complexes 2؊4 with neutral N-acylamidines as ligands, these bonds are shorter by about 0.05 Å as a consequence of the formally anionic ligands. As in 2؊4 effective cyclic conjugation is indicated by the bond lengths of the ligands.…”

“…[1] In a recent paper we reported the synthesis and structural properties of two palladium(II) complexes of differently substituted tetrameric N-acylated and N-thioacylated oligonitriles. [2] The formation of six-membered chelate rings involving either two nitrogen atoms or one nitrogen and one sulfur atom were characteristic features of these complexes. We are now focussing on the copper(II) complexes of small donor substituted model oligonitriles, the N-acylamidines 1.…”

Multivalent 1‐Oxa‐3,5,7‐triazahepta‐1,3,5‐trienes: Synthesis, Structural Properties and Metal Coordination

“…Due to the polyunsaturated chain of adjacent C=N units, special electronic and molecular structures as well as interesting redox and NLO properties are observed 1. These oligomers offer oxygen and nitrogen lone pairs as potential binding sites for metal complexation 1,2. In particular, branched pyridine‐based pincer ligands (Scheme ) have found applications as powerful ligands for the complexation of various transition metal ions 3.…”