Reactivity of 4-Aminopyridine with Halogens and Interhalogens: Weak Interactions Supported Networks of 4-Aminopyridine and 4-Aminopyridinium

Abstract

The reaction of 4-aminopyridine (4-AP) with ICl in a 1:1 molar ratio in CH2Cl2 produced the expected charge-transfer complex [4-NH2-1λ 4-C5H4N-1-ICl] (1·ICl) and the ionic species [(4-NH2-1λ 4-C5H4N)2-1μ-I+]­[Cl–] (2·Cl–) in a 2:1 relation, as indicated by 1H NMR spectroscopy in solution. In contrast, only the ionic compound [(4-NH2-1λ 4-C5H4N)2-1μ-I+]­[IBr2 –] (2·IBr2 –) was observed in the analogous reaction with IBr. The reaction between 4-AP and I2 in a 1:1 molar ratio also afforded two components, one of which was identified as the congeneric cation in [(4-NH2-1λ 4-C5H4N)2-1μ-I+]­[I7 –] (2·I7 –) that contains a polyiodide anion as a result of transformation in a 1:2 molar ratio between the starting materials. In all of these ionic products, the crystal structures feature an iodonium ion, I+, trapped between two 4-AP rings through N···I+···N contact. Surprisingly, the reaction of 4-AP with Br2 in CH2Cl2 resulted in an immediate protonation of the 4-aminopyridine (1H NMR) and [4-NH2-1λ 4-C5H4N-1-H+]­[Br–] (3·Br–) was characterized as the main product. A subsequent peculiar bromination–dimerization process afforded the novel pyridyl-pyridinium cations {3,3′,5′-Br3-1λ 4-[1,2′-(C5H4N)2]-4,4′-(NH2)2}+[X–] (4·Br–, 4·Br3 –) and {3′,5′-Br2-1λ 4-[1,2′-(C5H4N)2]-4,4′-(NH2)2}+[X–] (5·Br–, 5·Br3 –). Compounds 1–5 as well as two protonated species, [4-NH2-1λ 4-C5H4N-1-H+]2[Cl–]­[I3 –] (3 2·Cl–·I3 –) and [(4-NH2-1λ 4-C5H4N)2-1μ-H+]­[I–] (6·I–), all display extended 3D networks supported by halogen and hydrogen bonding in the solid state.

Noncovalent Bonds, Spectral and Thermal Properties of Substituted Thiazolo[2,3-b][1,3]thiazinium Triiodides

“…The compound 2-(cinnamylsulfanyl)benzo[d]thiazole (1a) was analyzed by 1 H NMR (CDCl3, ppm): 7.90 (d, J = 8.2 Hz, HAr); 7.74 (d, J = 7.9 Hz, HAr); 7.44-7.38 (m, HAr); 7.38-7.32 (m, 2HAr); 7.31-7.26 (m, HAr); 7.25-7.20 (m, HAr); 6.70 (d, J = 15.7 Hz, =CH-); 6.37 (dt, J = 15.0, 7.3 Hz, =CH-); 4.17 (2Н, d, J = 7.3 Hz, -CH2-). It was also analyzed by 13 [49].…”

“…Variation of the N-and S-containing heterocyclic cations is useful for the investigation of bonding properties in organic polyiodide crystals. The chemistry of polyhalides has attracted particular attention due to the vast diversity of applicable properties related to the ability of halogens to form different types of contacts [10][11][12][13][14][15]. Polyiodides represent an absolute majority among polyhalide structures [16][17][18][19][20][21].…”

“…Dark brown crystals were filtered and dried in vacuo (yield 0.46 g, 98%). 2H Ar ); 7.50-7.43 (m, H Ar ); 7.38-7.24 (m, H Ar ); 7.01 (1H, s, 4-H); 5.69 (1H, dd, J = 5.9, 3.0 Hz, 3-H); 3.70 (1H, dd, J = 14.6, 3.4 Hz, 2-H); 3.40 (1H, dd, J = 14.6, 2.8 Hz, 2-H) and13 C NMR (DMSO-d6, ppm): 175.96; 140.67; 135.42; 129.60 (2C); 129.50; 129.18; 128.24; 127.43; 126.15 (2C); 124.53; 114.67; 66.33; 33.78; 17.19. Elemental analysis calc.…”

Iodine(I) and Silver(I) Complexes of Benzoimidazole and Pyridylcarbazole Derivatives

“…[20][21][22][23][24][25] The exceptional strength of 3c-4e halogen bonds in halogen(I) complexes has made these an interesting sub-class of halogen-bonded complexes, however, due to their inherent reactivity only a few tens of unique iodine(I) complexes have been reported to date in the solid-state. [13,[26][27][28][29][30][31][32][33][34] There are no reported X-ray structures of iodine(I) complexes with bicyclic aromatic amines such as benzoimidazoles or quinolines. Herein, benzoimidazole and pyridylcarbazole derivatives were chosen to probe halogen bonding with polycyclic and larger XB acceptors leading to eight new [NÀ IÀ N] + halogen(I) (also known as halonium) and [NÀ AgÀ N] + silver(I) complexes in the solid-state, along with compelling evidence of halogen(I) complex formation in solution.…”

Polycentric binding in complexes of trimethylamine-N-oxide with dihalogens

“…A few reports on computations for cationic halogen complexes 34 demonstrated the thermodynamic stability of these forms. A number of computations for "halogen donor-heteroatom acceptor" interactions always led to molecular species (see reviews 22,23 and references therein) with different degrees of covalent bond polarization.…”