Crystal and molecular structure of a hexaazamacrocycle

Abstract

The crystal and molecular structure of the hexaazamacrocycle C24HI4N6 has been determined from X-ray diffractometer data. The crystals are monoclinic, space group P21/c with a = 4.416(1), b = 9.972(4), c = 18.955(12) A,/3 = 95.48(4) ~ and Z = 2. The structure was derived from 536 reflections using direct and Fourier methods and was refined by least squares to R = 0.038. The polar molecules form stacks along the a axis with an inclination of 68 ~ and an interplanar distance of 3.32 A,. The size of the central hole of the molecule is defined by the diagonal distances N(2) 9 9 9 N(2') = 3.681 (10) and N(3) 9 . 9 N(3') = 3.771(9) A of the o-phenanthroline nitrogens. This is too small to accommodate Pd 2+ or Pt 2+ in the hole.

Cobalt complexes of tetradentate, bipyridine-based macrocycles: their structures, properties and photocatalytic proton reduction

“…The crystal structures coincide with this hypothesis; the bond lengths of C22-C25 (complexes 2a and 3a) and C11-C12 (complex 4a), respectively, are in the range between 1.567(2) and 1.577(2) Å, and thus significantly longer than a common single bond between two sp 3 hybridized carbon atoms (1.53 Å). 36 The sum of the three angles between the pyridyl units and the nitrile group, centered at the bridging carbons, ranges between 327.9(5)°and 330.17 (28)°for the ligands 3 and 5 but is substantially widened to 334.26(25)°a nd 336.87 (24)°for the three complexes 2a-4a. Upon metallation, the bpy units become almost coplanar relative to each other.…”

“…19,22,23 A particularly interesting property of pyrphyrins or their aza-bridged analogues is the tautomerism between a formally doubly condensate bpy and a fully conjugated macrocycle (Scheme 1b). 18,[24][25][26] The success of acyclic polypyridyl of Co II in proton reduction was our incentive to study their cyclic tetradentate congeners [27][28][29][30][31] and to investigate their properties and applications. In this work, syntheses, characterization and performance of Co II pyrphyrin complexes in aqueous photocatalysis are presented.…”

One-pot gram-scale rapid synthesis of MN4 complexes with 14-membered ring macrocyclic ligand as a precursor for carbon-based ORR and CO2RR catalysts

“…[3][4][5][6] From this perspective, 14MR-MN 4 complexes with H 2 HAM ligand (Fig. 1) [7][8][9] -which has two phenanthroline moieties linked by NH groups-have attracted considerable attention as promising precursors for developing innovative ORR and CO 2 RR catalysts both experimentally and theoretically, because these 14MR-MN 4 complexes possess a kind of model-structure for the catalytic active site of these carbon-based catalysts. [10][11][12][13][14][15][16][17][18][19][20][21] Recently, our group reported the synthesis of 14MR-FeN 4 complexes and evaluated their application as a precursor for electrochemical ORR catalysts.…”

“…3–6 From this perspective, 14MR-MN 4 complexes with H 2 HAM ligand (Fig. 1) 7–9 —which has two phenanthroline moieties linked by NH groups—have attracted considerable attention as promising precursors for developing innovative ORR and CO 2 RR catalysts both experimentally and theoretically, because these 14MR-MN 4 complexes possess a kind of model-structure for the catalytic active site of these carbon-based catalysts. 10–21…”

A Pyridinic Fe-N4 Macrocycle Effectively Models the Active Sites in Fe/N-Doped Carbon Electrocatalysts

“…Towards realizing the above goal, we searched the literature for pyridinic N4 macrocyclic ligands. Notably, the aza-bridged bis-1,10-phenanthroline hexaazamacrocycle, (phen2N2)H2 (phen2N2 = 1,14:7,8diethenotetrapyrido[2,1,6-de:2',1',6'-gh:2",1",6"-kl:2"',l"',6"'-na] [1,3,5,8,10,12]hexaazacyclotetradecine), as well as its cobalt(II), nickel(II) and copper(II) complexes have been reported [83][84][85][86][87][88] and applied to DNA binding studies 89 and carbon dioxide reduction catalysis. [90][91][92][93] Despite this precedent, the synthesis and ORR activity of the corresponding (phen2N2)Fe fragment 82 has, to the best of our knowledge, been unexplored.…”