ab,cf-Bis[4-(2-aminoethyl)imidazole-N3,N8]-de-bis(isothiocyanato)nickel(II)

Wojtczak, Andrzej; Jaskólski, M.; Kosturkiewicz, Z.

doi:10.1107/s0108270185009325

Cited by 4 publications

(2 citation statements)

References 3 publications

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“…The bond lengths and angles in the imidazole rings of the histamine ligands are comparable with those found in imidazole or histamine complexes (Gtowiak & Wn~k, 1985a,b;Clegg, Acott & Garner, 1984;Wojtczak et al, 1983Wojtczak et al, , 1985; and references cited therein). However, the angles are different from those found in histaminium or imidazolium cations, imidazolate anions and imidazole (Yamane, Ashida & Kakudo, 1973;Bonnet & Jeannin, 1972;Fuess, Hohlwein & Mason, 1977;Freeman, Huq, Rosalky & Taylor, 1975;Kolks & Lippard, 1984;Ivarsson, Lundberg & Ingri, 1972;Craven, McMullan, Bell & Freeman, 1977; and references cited therein).…”

Section: Lengths (T~) and Bond Angles (°) With Their Esd 'Ssupporting

confidence: 53%

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Structure of catena-bis[4-(2-aminoethyl)imidazole-N3,N8]-μ-chloro-copper(II) chloride dihydrate

Wojtczak¹,

Jaskólski²,

Kosturkiewicz³

1987

Acta Crystallogr C

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The distortion of the square pyramid is also important, but less severe than that of the trigonal bipyramid. The four basal atoms N(1), N(2), Br(1) and Br(2) deviate strongly from coplanarity by 0.240, -0.247, -0-183 and 0.190 A, respectively, while the Cu atom deviates from this plane by 0.252 A in the direction of the apical Br atom. The dihedral angle between the unweighted mean planes N(1)-Cu-N(2) and Br(1)-Cu-Br(2) is 24.9 °, thus indicating a distortion towards tetrahedrality, which is quite common in '4 + 1' complexes. The distances and angles of the di-2-pyridylmethane ligand are comparable with those found by us for chloro(di-2-pyridylmethane)-(di-2-pyridylmethanol)copper(II) perchlorate (Garland, Le Marouille, Spodine & Manzur, 1986).The structure of the dibromo(di-2-pyridylmethane)-copper(II) complex is similar to that found in the bis[dibromo(4-methyloxazole)copper(II)] complex (Marsh et al., 1982), in the sense that all metal-ligand distances are comparable. However, in their case the Cu atom deviates from the basal plane of the pyramid by 0.309 A, and the in-plane Br(1)--Cu--Br (2)

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Section: Lengths (T~) and Bond Angles (°) With Their Esd 'Ssupporting

confidence: 53%

“…Bond lengths and angles in the side chains are similar to those found in other histamine complexes, e.g. Wojtczak et al (1983Wojtczak et al ( , 1985. Each histamine molecule forms two coordinate bonds to the Cu 2+ ion via the N ' atom of the imidazole ring and the amino group of the side chain.…”

Section: Lengths (T~) and Bond Angles (°) With Their Esd 'Ssupporting

confidence: 51%

Structure of catena-bis[4-(2-aminoethyl)imidazole-N3,N8]-μ-chloro-copper(II) chloride dihydrate

Wojtczak¹,

Jaskólski²,

Kosturkiewicz³

1987

Acta Crystallogr C

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Tautomerism of neutral and monoprotonated histamine—a comparison of semi‐empirical and ab initio quantum mechanical predictions for ‘essential’ and ‘scorpio’ conformations

Raczyńska

Darowska

Rudka

et al. 2001

J of Physical Organic Chem

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Relative energies were calculated at different semi‐empirical (CNDO, INDO, MINDO/3, MNDO, AM1, and PM3) and ab initio levels (RHF/STO‐3G//STO‐3G, RHF/STO‐4G//STO‐4G, RHF/3‐21G//3‐21G, RHF/6‐31G//6‐31G, RHF/6‐31G*//6‐31G, RHF/6‐31G*//6‐31G*, RHF/6‐31 ++ G**//6‐31G*, RHF/6‐311 ++ G**/6‐31G*, RHF/6‐31G**//6‐31G**, RHF/31 ++ G**//6‐31 ++ G**, MP2/6‐31G*//6‐31G* and MP2/6‐31G**//6‐31G**) for so‐called ‘essential’ (trans) and ‘scorpio’ (gauche) conformations of the neutral and monoprotonated histamine tautomers. For the monocationic forms, the polarizable continuous model was applied to geometries optimized at the RHF/6‐31G* level. The comparison shows that, generally, both types of calculation (semi‐empirical and ab initio) predict the same tautomeric preference for the conformations of histamine and its monoprotonated cation when not interacting with the environment, i.e. for conditions corresponding to the gas phase. For the monocation, the ring N‐aza protonated form (ImH+) is favoured in the gas phase for both conformations (trans and gauche); this is contrary to water solution, where the chain N‐amino (AmH+‐T1) predominates. This difference results mainly from the high polarizability of the imidazole ring in the gas phase which is strongly reduced in solution. Some ‘discrepancies’ are only observed for neutral histamine, for which the relative energy is close to zero. Good agreement of results predicted by various methods can result from the fact that in histamine the proton is transferred between atoms of the same element (nitrogen). Copyright © 2001 John Wiley & Sons, Ltd.

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Ab initio study of tautomerism and of basicity center preference in histamine, from gas phase to solution—comparison with experimental data (gas phase, solution, solid state)

Raczyńska

Darowska

Cyrański

et al. 2003

J of Physical Organic Chem

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epoc ABSTRACT: Tautomeric and basicity center preferences for isolated neutral and monoprotonated histamine were studied by means of ab initio calculations (HF, MP2 and DFT). The polarizable continuum model (PCM) was applied to the study of the variations of the tautomeric and basicity center preferences in histamine on going from the gas phase to aqueous solution. Twelve solvents of different polarities (from n-heptane to water) were chosen and calculations were performed for geometries optimized at the HF/6-31G* level. In low-polarity solvents and in the gas phase the protonation site is identical. A change of the preferred site of protonation takes place in solvents containing heteroatoms (except tetrachloromethane). Under the same conditions, a variation of the tautomeric preference in the monocation occurs. The ring N 2 -protonated form (ImH þ )-favored in gas phase-is also preferred in non-polar solvents (n-heptane, benzene, tetrachloromethane). The ImH þ form becomes less important in more polar solvents. In such a case, the chain N 3 -protonated form (AmH þ -T 1 ) predominates. For the neutral histamine, solvation has a relatively small influence on the relative energies (variations are less than 1 kcal mol À1 ), and does not change the tautomeric preference (HA-T 2 ). Calculated basicity parameters were compared with those obtained experimentally in the gas phase and in aqueous solution. In the gas phase, the experimental ('macroscopic') basicity parameter (PA) is close to the 'microscopic' PA calculated for the gauche conformation. In aqueous solution, the microscopic pK a order is similar to that of the E prot calculated for the trans conformation. In the solid state, both forms of histamine (neutral and monoprotonated) prefer the trans conformation. Some exceptions occur for complexes with metals.

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ab,cf-Bis[4-(2-aminoethyl)imidazole-N3,N8]-de-bis(isothiocyanato)nickel(II)

Abstract: Abstract. [Ni(NCS)2(C5H9N3)2

Cited by 4 publications

References 3 publications

Structure of catena-bis[4-(2-aminoethyl)imidazole-N3,N8]-μ-chloro-copper(II) chloride dihydrate

Structure of catena-bis[4-(2-aminoethyl)imidazole-N3,N8]-μ-chloro-copper(II) chloride dihydrate

Tautomerism of neutral and monoprotonated histamine—a comparison of semi‐empirical and ab initio quantum mechanical predictions for ‘essential’ and ‘scorpio’ conformations

Ab initio study of tautomerism and of basicity center preference in histamine, from gas phase to solution—comparison with experimental data (gas phase, solution, solid state)

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