The effect of different ligand substituents on the chemistry of a zinc–pyrazole anion host

Abstract

The influence of the pyrazole ligand on the previously reported anion host [ZnCl(Hpz tBu ) 3 ] + (Hpz tBu = 5-tert-butylpyrazole) has been investigated. Reaction of ZnCl 2 with 3 equiv. of 3{5}-cyclohexylpyrazole (Hpz Cy ) or 3{5}-phenylpyrazole (Hpz Ph ) affords [ZnCl(Hpz R ) 3 ]Cl (R = Cy or Ph), both of which undergo decomposition to [ZnCl 2 (Hpz R ) 2 ] upon recrystallisation. A similar reaction using 3{5}-(thien-2-yl)pyrazole (Hpz Tn ) affords [ZnCl 2 (Hpz Tn ) 2 ] only. The salts [ZnCl(Hpz Ph ) 3 ]BF 4 , [ZnCl(Hpz Cy ) 3 ]X (X À = NO 3 À , ClO 4 À , CF 3 SO 3 À or 1 2 SO 4 2À ) and [ZnBr(Hpz Cy ) 3 ]NO 3 ÁH 2 O have been isolated, by performing the above reactions in the presence of 1 equiv. of AgX. The cations in [ZnCl(Hpz Cy ) 3 ]NO 3 associate into a dimeric capsule encapsulating two nitrate anions. In contrast, [ZnBr(Hpz Cy ) 3 ]NO 3 ÁH 2 O contains hydrogen-bonded [NO 3 ÁH 2 O] n nÀ chains enclosed within channels formed by the complex cations, while [ZnCl(Hpz Cy ) 3 ]ClO 4 forms a different hydrogen-bonded dimer with the anions occupying two shallow cavities in its surface. These data imply that anion binding by [ZnCl(Hpz R ) 3 ] + depends strongly on the steric and inductive properties of the pyrazole 'R' substituents.

Two Heptacopper(II) Disk Complexes with a [Cu7(μ3-OH)4(μ-OR)2]8+Core

“…During our continuing studies into the supramolecular chemistry of metal/pyrazole derivatives, , we have reported cyclic hexanuclear complexes based on 3-pyridyl-5- tert -butylpyrazole (LH). − These include [Cu 6 (μ-F) 6 (μ-L) 6 ] ( 1 ), which can bind Na + , K + , or NH 4 + at the center of its [Cu 6 (μ-F) 6 ] 6+ ring, , like a traditional (inverse) metallacrown, but also possesses two chiral cavities formed by the L − ligands. The cavities project above and below the metal core, and each has three F − hydrogen-bond acceptors at its base.…”

Crystal structure of chlorido-tris(3-amino-5-phenyl-1Hpyrazole- N2)zinc(II) chloride, [ZnCl(C9H9N3)3]Cl

“…These interactions favour the edge-on orientation of the ligands regarding the two Cl atoms. Similar orientation of the ligands has been observed in the complex of Zn(II)w ith the monosubstituted 3(5)-phenylpyrazole [8].I nt he case of the ligands a and b the above interactions to the ionic Cl2 areaccompanied by weak C5-H×××Cl2interactions engaging the phenyl Cas donor with d(C5×××Cl2) =3 .782(9) and 3.680(6) Å, respectively. The similar contact is missing for ligand c where the twisting of ph ring is the most pronounced.…”

“Scorpionate-like” complexes that are held together by hydrogen bonds: Crystallographic and spectroscopic studies of (3-NH(t-butyl)-5-methyl-pyrazole) MX2 (M = Zn, Ni, Co, Mn; n= 3, 4; X = Cl, Br)

“…Other examples of anion binding through hydrogen bonds have been reported in the literature. [39][40][41][42][43] Complex 2 is also relatively stable in the mass spectrometer, with the loss of an HCl unit occurring before it reaches the detector and the observed ion corresponds to [(LH) 2 (L)CoCl] + . For complex 3, the relative weakness of hydrogen bonds and metal to pyrazole interactions is shown by the loss of L and Cl prior to reaching the detector with the FAB MS method, and the loss of one pyrazole ring (LH) when using the softer LIFDI method.…”