Cobalt(II), nickel(II), and copper(II) complexes of 14-membered hexaazamacrocycles: synthesis and characterization

Abstract

Cobalt(II), nickel(II), and copper(II) complexes containing 5,12-di(4-bromophenyl)-7, 14-dimethyl-1,2,4,8,9,11-hexaazacyclotetradeca-7,14-diene-3,10-dione (H 2 L 1 ) and 5,12-diphenyl-7,14-dimethyl-1,2,4,8,9,11-hexaazacyclotetradeca-7,14-diene-3,10-dione (H 2 L 2 ) have been synthesized. All complexes were characterized by elemental analysis, MALDI TOF-MS spectrometry, and electronic absorption spectroscopy. The crystal structures of two compounds, [Cu 2 (H 2 L 1 )Cl 4 ] n and [NiL 2 ], were determined by X-ray powder diffraction. In the polymeric [Cu 2 (H 2 L 1 )Cl 4 ] n , the Cu 2 Cl 4 units and H 2 L 1 molecules are situated on inversion centers. Each Cu(II) has a distorted trigonal-bipyramidal coordination environment formed by N and O from H 2 L 1 [Cu-N 2.340(14) Å, Cu-O 1.952(11) Å], two bridging chlorides [Cu-Cl 2.332(5), 2.279(5) Å] and one terminal chloride [Cu-Cl 2.320(6) Å]. In the [NiL 2 ] complex, the Ni(II) situated on inversion center has a distorted square-planar coordination environment formed by four nitrogens from L 2 [Ni-N 1.860(11), 1.900(11) Å].

Nickel(II), Copper(II) and Palladium(II) Complexes with Bis-Semicarbazide Hexaazamacrocycles: Redox-Noninnocent Behavior and Catalytic Activity in Oxidation and C–C Coupling Reactions

“…0.025 Å) longer than Ni–N3 in nickel­(II) complex 4 . The difference between these two bonds in the nickel­(II) complex with IX where Ar = Ph (Scheme ) with Ni–N hydrazine = 1.900(11) Å and Ni–N amide = 1.860(11) Å is not significant . In the case of copper­(II) complexes 2·EtOH and 5 the bond length difference is quite significant and amounts to ca.…”

“…In contrast, the nickel(II) complex of trans-IX (Ar = Ph) is involved in strong intermolecular interactions of lactam groups via centrosymmetric N−H•••O hydrogen bonds, as shown in Figure S15. 57 As mentioned previously, this might be a reason for the low solubility of the nickel(II) complexes in common organic solvents and water.…”

“…The difference between these two bonds in the nickel(II) complex with IX where Ar = Ph (Scheme 1) with Ni−N hydrazine = 1.900(11) Å and Ni−N amide = 1.860(11) Å is not significant. 57 In the case of copper(II) complexes 2•EtOH and 5 the bond length difference is quite significant and amounts to ca. 0.1 Å, while the difference in Pd−N hydrazine and Pd−N amide interatomic distances has vanished in 6 (statitically equal within 3σ).…”

Novel Semicarbazone-Based Amidoalkylation Reagents: Preparation and Application to the Stereoselective Synthesis of 14-Membered Hexaaza Macrocycles

“…Powder X-ray diffraction analysis 13a and DFT calculations showed that the internal cavity of macrocycles 1 is able to chelate various metal cations through the N1, N4, N8, and N11 atoms. Indeed, the neutral complex of dianion of 1 (R = Ph, R 1 = H) with Ni(II) was obtained, 14 demonstrating that hexaaza macrocycles 1 can serve as novel tetradentate ligands for metal ions. However, progress in this area was hampered by the low availability of macrocycle precursors 2 which were prepared in four steps from ethyl carbamate involving α-amidoalkylation of sodium acetylacetonates with ethyl N-(tosylmethyl)carbamates.…”

Development of molecular catalysts for H2 evolution and modified copper catalyst for CO2 reduction

“…46,47 Furthermore, Nam, Fukuzumi, and others have recently extended the applications of TAML compounds to other applications such as oxidative C-H activation by high-valent Co and Ni complexes. 40,[48][49][50][51][52][53][54][55][56][57] These seminal studies highlight the oxidative robustness of TAML systems, but also underscore the paucity of reports on the reductive catalytic activity of these potentially nucleophilic late transition metal -ate complexes.…”