Molecular mechanics and crystallographic study of hole sizes in nitrogen-donor tetraaza macrocycles

Thöm, Vivienne J.; Fox, Christine C.; Boeyens, Jan C. A.; Hancock, Robert D.

doi:10.1021/ja00332a032

Cited by 152 publications

(68 citation statements)

References 3 publications

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“…1). The Ni--N distances of 1.919 (2) and 1.929 (2) A are similar to those found in other nickel(H) tetraaza macrocycles (Thom, Fox & Boeyens, 1984). The Ni atom in the anion also lies on an inversion centre and is surrounded by a square plane of four S atoms.…”

supporting

confidence: 80%

[1,8-Bis(2-hydroxyethyl)-1,3,6,8,10,13-hexaazacyclotetradecane]nickel(II) Bis(maleonitriledithiolato)nickelate(II)

Shan¹,

You²,

Fun³

et al. 1996

Acta Crystallogr C

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supporting

confidence: 80%

[1,8-Bis(2-hydroxyethyl)-1,3,6,8,10,13-hexaazacyclotetradecane]nickel(II) Bis(maleonitriledithiolato)nickelate(II)

Shan¹,

You²,

Fun³

et al. 1996

Acta Crystallogr C

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“…So-called H-clashes are generally regarded as responsible for the large decrease in formation constants of a number of complexes. 1,[19][20][21] Our focus here is on Ni(II) (an average-size metal ion, ionic radius 0.69 Å) 18 complexes with NTA and NTPA where a decrease in formation constant of ∆log K 1 ≈ 5.7 is observed when three 5m-CRs present in NiNTA are replaced by three 6m-CRs to form NiNTPA. A competition reaction between NTA and NTPA for Ni(II) in the solvent (water) is used to theoretically compute a formation constant of the NiNTPA complex.…”

Section: But This Does Not Apply To the Formation Constants Of Metal mentioning

confidence: 99%

A Density Functional Theory- and Atoms in Molecules-based Study of NiNTA and NiNTPA Complexes toward Physical Properties Controlling their Stability. A New Method of Computing a Formation Constant

Cukrowski

Govender

2010

Inorg. Chem.

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The log K 1 value of analytical quality was obtained for the NiNTPA complex using the DFTcomputed (at the B3LYP/6-311++G(d,p) level of theory in solvent, CPCM/UAKS) G (aq) values of the lowest energy conformers of the ligands, NTA (nitrilotriacetic acid) and NTPA (nitrilotri-3-propanoic acid), and Ni(II) complexes (NiNTA and NiNTPA). The described mathematical protocol is of general nature. The topological analysis, based on the Quantum Theory of Atoms in Molecules (QTAIM) of Bader, was used to characterize coordination bonds, chelating rings and additional intramolecular interactions in the complexes. The topological data, but not the structural analysis, explained the observed difference in stability of the NiNTA and NiNTPA complexes. It was found that the structural H···H contacts (classically regarded H-clashes, a steric hindrance destabilizing the complex) are in fact the H-H bonds contributing to the overall stability of NiNTPA. Also a CH-O bond was found in NiNTPA. The absence of intramolecular bonds between the atoms that fulfill a distance criterion in NiNTPA is explained by the formation of adjacent intramolecular rings that have larger electron density at the ring critical points when compared with the rings containing these atoms. It is postulated that the strength of a chelating ring (a chelating effect) can be measured by the electron density at the ring critical point. It was found that the strain energy, E s , in the as-in-complex NTPA ligand (E s is significantly lowered by the presence of the intramolecular bonded interactions found by QTAIM) is responsible for the decrease in strength of NiNTPA; the E s ratio (NTPA/NTA) of 1.9 correlates well with the experimental log K 1 ratio (NTA/NTPA) of 1.98.2

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“…Those with ioslated octahedra seem to have slightly, but possibly significantly, longer distances than those where X-is shared between adjacent octahedra. The 'best-fit' distance is calculated as 2.07/~ by Martin, De Hayes, Zompa & Busch (1974) and a value of 2.05 A is obtained from molecular-mechanics calculations (Th6m, Fox, Boeyens & Hancock, 1984).…”

Section: * Equivalent Positions Formentioning

confidence: 99%

The structure of Ni(cyclam)(ClO4)2

Prasad¹,

Nyburg²,

McAuley³

1987

Acta Crystallogr C

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Molecular mechanics and crystallographic study of hole sizes in nitrogen-donor tetraaza macrocycles

Cited by 152 publications

References 3 publications

[1,8-Bis(2-hydroxyethyl)-1,3,6,8,10,13-hexaazacyclotetradecane]nickel(II) Bis(maleonitriledithiolato)nickelate(II)

[1,8-Bis(2-hydroxyethyl)-1,3,6,8,10,13-hexaazacyclotetradecane]nickel(II) Bis(maleonitriledithiolato)nickelate(II)

A Density Functional Theory- and Atoms in Molecules-based Study of NiNTA and NiNTPA Complexes toward Physical Properties Controlling their Stability. A New Method of Computing a Formation Constant

The structure of Ni(cyclam)(ClO4)2

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