Synthesis of Secondary, Tertiary and Quaternary 1,3,5‐Triazapenta‐1,3‐dienes and Their Co^II, Zn^II, Pd^II, Cu^II and BF₂ Coordination Compounds

Abstract

The secondary and tertiary 1,3,5-triazapenta-1,3-dienes 2 and 3 are easily obtained by the reaction of N-imidoyl chlorides with amidines or from ethyl N-imidoylimidoates 5 and primary amines. In a new synthetic pathway the compounds 5 were prepared by the reaction of imidoates in their protonated or free form with N-imidoyl chlorides. A quaternary 1,3,5-triazapenta-1,3-diene 4a is obtained by the reaction of the imidoate 5b with pyrrolidine. X-ray diffraction studies of the tertiary 1,3,5-triazapenta-1,3-diene 3c and its protonated form 3c·HCl allow the comparison of different patterns of intermolecular hydrogen bonding in the solid state. Two equivalents of a secondary 1,3,5-triazapenta-1,3-diene 2 were treated at room temperature after deprotonation with potassium tert-butoxide with CuCl 2 , Ni(ClO 4 ) 2 or with Pd(ac) 2 (without deprotonation) to give the corresponding neutral 2:1 chelate complexes (2a) 2 ·Cu, (2a) 2 ·Ni and (2b) 2 ·Pd, respectively. A fluorescent boron complex 2b·BF 2 was obtained by

Fluorescent benzene-centered mono-, bis- and tris-triazapentadiene–boron complexes

“…16 Bis-and tris-triazapentadiene ligands 6c-e: the procedure used for 6b is also the basis for the preparation of the bis-triazapentadienes 6c-d 20 and the novel three-armed tristriazapentadiene ligand 6e (Scheme 3).…”

“…12 In 1962 the first neutral 1 : 1 triazapentadiene-boron complex was synthesized by Milks et al 13 and, a decade later, Mikhailov et al started to intensively study the synthesis of similar complexes. 14 Since then, only a small number of research groups including ours [15][16][17][18] have studied this class of neutral triazapentadiene-boron complexes. Species with such compositions and structural properties have not yet received intense attention, with some aza-boron-dipyridomethenes and aza-boron-diquinomethene systems showing the closest similarity to our compounds.…”

PdII‐Promoted Single‐Pot Template Transformations of Benzonitriles, Cyanoguanidine and Sodium Dicyanamide with the Formation of Symmetrical and Asymmetrical (1,3,5‐Triazapentadienate)palladium(II) Complexes

“…phenyls, and can be synthesized by the reaction of primary amines, RNH 2 , with the fluorinated imine C 3 F 7 -CF=N-C 4 F 9 [6] or by the Ley and Muller method [23] where amidine is treated with an N-imidoyl chloride. [3][4][5]12] Another route to tap-Pd complexes involves template transformations of cyanopyridines [10,16] through lithium amidinate, which is produced in situ from LiN(SiMe 3 ) 2 [10] or via an oxime-mediated process. [16] In the latter case, the synthesized complexes were shown [16] to display catalytic activity towards Suzuki-Miyaura and Heck cross-coupling reactions.…”

“…[3,5,6,12] These pre-prepared tap ligands usually contain N 1 ,N 3 nitrogen atoms connected to bulky groups, e.g. phenyls, and can be synthesized by the reaction of primary amines, RNH 2 , with the fluorinated imine C 3 F 7 -CF=N-C 4 F 9 [6] or by the Ley and Muller method [23] where amidine is treated with an N-imidoyl chloride.…”

“…[17][18][19][20] Until now only copper, nickel and platinum ions have been studied in these transformation reactions and no data on palladium(II)-mediated transformations have been reported, irrespective of the potential ability of Pd II to form tap complexes [3,5,6,10,12,16] and its expected behavioural similarity to that of Pt II in promoting nucleophilic addition reactions with substrates containing the CϵN group, namely organonitriles. [24][25][26][27] Thus, one can conclude that the template conversions of CϵN-containing reagents to tap ligands bound to Pd II cen-ters deserve to be explored further as a convenient route to new tap-palladium(II) complexes.…”