The Coordination Chemistry of 1,4‐Diazepan‐6‐amine

Abstract

The new, tridentate, facially coordinating ligand 1,4-diazepan-6-amine (daza) has been prepared from ethane-1,2-diamine and 2,3-dibromo-1-propanol in a seven-step procedure with an overall yield of 22 %. The conformation of the free ligand has been elucidated by pH-and temperaturedependent 1 H NMR spectroscopy and by a single-crystal Xray structure analysis of H 3 dazaCl 3 ·H 2 O. A twisted chair with a predominantly equatorial orientation of the primary amino group has been established for daza and its protonation products

Chelation versus Binucleation: Metal Complex Formation with the Hexadentate all‐cis‐N1,N2‐Bis(2,4,6‐trihydroxy‐3,5‐diaminocyclohexyl)ethane‐1,2‐diamine

“…Additional titrations with sample solutions where the ligand was present in excess have then been performed. They were consistent with the previous results and did not provide evi- 5 + with the other taci subunit remaining protonated; [16,32] this assignment is in agreement with l max = 683 and 658 nm observed for the corresponding facial Cu II -tria-…”

“…It is well established that protonation of a basic site causes a deshielding of the neighboring CÀH protons, and this effect increases with a decreasing number of bonds between the basic site and the hydrogen atom under consideration. [14][15][16] The particularly strong shift observed for H1 and H5 in the range of 2 pH 4 together with the negligi- x + (x % 5.6) at pH* = 3.0. [43] The significant H2-C4 and H4-C2 coupling (black arrows) and the non-observance of H1-C3 and H3-C1 coupling (circles) indicate a chair conformation with axial hydroxy groups; the H1-C5 and H5-C1 couplings (white arrows) prove the interlinking of the two taci moieties by an ethylene bridge.…”

Di-μ-chlorido-bis[chlorido(1,4,6-trimethyl-6-nitro-1,4-diazepine)copper(II)]

“…For related literature, see: Belousoff et al (2006); Deal & Burstyn (1996); Fry et al (2005); Hegg & Burstyn (1998); Peralta et al (2005) ;Rodriguez, et al (1999); Romba et al (2006). For the synthesis of the meaaz-NO 2 ligand see Ge et al (2006).…”

“…Tridentate ligands that are able to force facial geometry, such as 1,4,7-tacn (1,4,7-triazacyclononane), daza (1,4-diazepan-6-amine) (Romba, et al, 2006), tach (cis,cis-1,3,5-triaminocyclohexane) (Hegg & Burstyn, 1998), play an important role in the stabilization of a great number of structural motifs in coordination compounds and in biological systems (Peralta et al, 2005). Copper complexes with this kind of ligand have been reported over the past few years with a view to the study of the hydrolysis of phosphate esters, proteins and DNA (Deal & Burstyn, 1996;Fry et al, 2005).…”

Iron(II) Complexes of Two Amine/Imine N5 Chelate Ligands Containing a 1,4‐Diazepane Core – To Crossover or Not To Crossover

“…This may be avoided by protecting the NH 2 functions in 1,2-ethylenediamine with p-toluenesulfonyl chloride (TsCl). [11] Upon deprotonation of the tosylamine groups with NaH or NaOH in tetrahydrofuran (THF), 1 is added as a solid and the reaction mixture is subsequently heated to reflux for several days. The suspension gradually turns brown, and ESI mass spectrometry is compatible with a mixture of 2 and 2a (2a is the monosubstituted side product.…”