[15]Crown-5: An Unsymmetrical Bifacial Hydrogen-Bond Acceptor in Crystal Engineering

Steed, Johathan W; Sakellariou, Evelina; Junk, Peter Courtney; Smith, Matthew K.

doi:10.1002/1521-3765(20010316)7:6<1240::aid-chem1240>3.0.co;2-v

Cited by 31 publications

(43 citation statements)

References 25 publications

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“…Evaporation of aqueous solutions equimolar in Ni(NO 3 ) 2 Á6H 2 O and 15-crown-5 invariably gave the compound [Ni(H 2 O) 6 ](NO 3 ) 2 Á15C5Á2H 2 O (see Steed et al, 2001). Attempts were then made to restrict the water available to the Ni 2+ ion, usually by recrystallizing from nonaqueous solvents.…”

Section: Synthesesmentioning

confidence: 99%

“…Before we were finally successful we had made five other compounds that all contained a sixcoordinate Ni 2+ ion (with at least two of the ligands being water molecules), nitrate ions and a 15-crown-5. The structure of one of these compounds (refcode XEMGIF) had been reported by Steed et al (2001), but the other four are new. The five compounds have water/Ni 2+ ratios as high as 8 and as low as 2.…”

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confidence: 94%

“…Tables of effective ionic radii (Shannon, 1976;Greenwood & Earnshaw, 1997) suggested that a Ni 2+ ion should fit inside the crown, but we found little precedent for such coordination. A survey of version 5.29 (November 2007plus January 2008 of the Cambridge Structural Database (Allen, 2002; hereafter the CSD) located coordinates for four structures (refcodes XEMGAX, XEMGEB, XEMGIF, XEMGOL; Steed et al, 2001) containing Ni 2+ , 15-crown-5, water and a simple counterion (NO 3 À , Br À or ClO 4 À ), but the Ni 2+ ion is not coordinated by the macrocycle in any of them. One entry {BIHFED; [Ni(EtOH) 2 (15C5)](PF 6 ) 2 ; Simonsen et al, 1982} does show a diagram with a Ni 2+ ion located inside the crown, but the reference is to a conference abstract, no coordinates are archived, R = 0.091, and it seems that no full structure report was ever published.…”

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confidence: 99%

“…Seven structures are reported here because two polymorphs were discovered for one of the six compounds. The structure XEMGIF is included because the original determination (Steed et al, 2001) was at 173 K and we wanted to be able to make comparisons at 90 K.…”

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confidence: 99%

“…have two or three independent formula units in the asymmetric unit. Steed et al (2001) noted the surprising frequency of large asymmetric units in co-crystals of 15C5 and simple metal complexes.…”

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confidence: 99%

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The elusive [Ni(H₂O)₂(15-crown-5)]²⁺ cation and related co-crystals of nickel(II) hydrates and 15-crown-5

Siegler¹,

Parkin²,

Selegue³

et al. 2008

Acta Crystallogr Sect B

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Initial attempts to make [Ni(H2O)2(15-crown-5)](NO3)2, i.e. to insert the Ni2+ ion into the 15-crown-5 macrocycle, gave the mono- (two polymorphs) and dihydrate of a co-crystal of[Ni(H2O)6](NO3)2 and 15-crown-5 (1,4,7,10,13-pentaoxacyclopentadecane=15C5). Synthetic routes designed to restrict the water available to the Ni2+ cation gave three additional compounds, [Ni(H2O)6](NO3)2-trans-[Ni(H2O)4(MeOH)2]-(NO3)2x2(15C5), cis-[Ni(H2O)4(NO3)2]-trans-[Ni(H2O)4-(NO3)2]x2(15C5) and [Ni(H2O)2(MeCN)(NO3)2]x15C5x-MeCN. All five compounds contain Ni2+ ions with two trans aqua ligands. In all six structures these aqua ligands make hydrogen bonds to the 15C5 molecules to form stacks in which the Ni complexes and 15C5 molecules alternate. The structures are surprisingly complicated: all are co-crystals,some are also solvates, and most have Z0 > 1. The target compound was finally prepared by heating pale green crystals of [Ni(H2O)6](NO3)2x15C5x2H2O to over 350 K and then cooling the resulting mixture of yellow crystals and solution to room temperature. Formation of the target compound seems to be favored at higher temperatures by a positive Delta(rxn)S(o) and an increased rate of ligand exchange.

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Section: Synthesesmentioning

confidence: 99%

mentioning

confidence: 94%

mentioning

confidence: 99%

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confidence: 99%

mentioning

confidence: 99%

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The elusive [Ni(H₂O)₂(15-crown-5)]²⁺ cation and related co-crystals of nickel(II) hydrates and 15-crown-5

Siegler¹,

Parkin²,

Selegue³

et al. 2008

Acta Crystallogr Sect B

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NMR and theoretical study of the cooperative interaction of hydrated proton with dibenzo‐24‐crown‐8

Křı́ž¹,

Dybal²,

Budka³

et al. 2008

Magnetic Reson in Chemistry

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Interaction of hydrated protons (HPs) with dibenzo-24-crown-8 (DBC in nitrobenzene-d(5) was studied by (1)H and (13)C NMR under assistance of ab initio-density functional theory (DFT) quantum calculations. HPs were afforded by hydrogen bis(1,2-dicarbollyl) cobaltate (HDCC) with 3.5 M excess of H(2)O. The forming of a complex between HP and DBC leads to marked and additive relative shifts of both (1)H and (13)C signals. This was utilized for the estimation of the stabilization constant K of the complex. Its value is at least 10(6) l/mol, which agrees with the result of independent extraction method (log K = 6.3). Using absolute integral intensities of the HP signal in a water-saturated system, it was shown that the form of HP present in the complex must be H(5)O(2)(+), in accord with formerly published structure of the complex in crystalline form. The investigation of the dynamics of exchange between bound and free DBC by transverse relaxation using variably spaced pulses in the Carr-Purcell-Meiboom-Gill (CPMG) sequence or on-resonance rotating-frame relaxation with variable spin-lock field intensity was partly hampered by the fast relaxation of some signals in the complex because of relative immobilization of its internal motions. In order to remove these effects, a pulse sequence dipolar interaction-free transverse relaxation (DIFTRE) for static DIFTRE was devised and the MLEV17 pulse sequence with high intensity of electromagnetic field was used in a separate series of experiments. Using the results of these latter experiments, the correlation time of exchange was established to be about 0.8 ms, which complied with the shape of the spectra. The accompanying ab initio DFT calculations showed that the apparent symmetry of the molecules of both DBC and its complex with H(5)O(2)(+) was probably the result of averaging of energetically close conformations (five for DBC and four for the complex). Both NMR and the calculations show that the basic mode of binding of the ion in the complex is analogous to that found in crystal but the most pronounced conformation is slightly different.

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Interaction of hydrated protons with octyl‐phenyl‐N,N‐diisobutylcarbamoylmethyl phosphine oxide (CMPO): NMR and theoretical study

Křı́ž

Dybal

Makrlík

et al. 2011

Magnetic Reson in Chemistry

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Interaction of octyl-phenyl-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO, the 'classical' rare metal extraction agent) with fully ionized hydrated protons (HP) was studied in acetonitrile-d(3) using (1)H, (13)C, (31)P NMR, PFG NMR and magnetic relaxation. The experimental results were confronted with high-precision ab initio DFT calculations. Relative chemical shifts of NMR signals of CMPO (0.01 mol/L) under the presence of HP in the molar ratio β = 0-2.0 mol/mol show binding between CMPO and HP. Self-diffusion measurements using (1)H PFG NMR demonstrate that larger complexes with higher content of CMPO are generally formed at β < 0.75. Analyzing the collective dependence of (13)C and (31)P NMR chemical shifts on β by the use of program LETAGROP, we obtained very good fitting for the assumed coexistence of two complexes (CMPO)(2)·HP (C(2)) and CMPO.HP (C(1)). The logarithms of the respective stabilization constants log K(i) were found to be 7.518 (C(2)) and 4.581 (C(1)). The system dynamics was studied by measuring the transverse (1)H NMR relaxation using CPMG sequence with varying delays t(p) between the π pulses in the mixtures with β = 0.4-0.8. The following exchange correlation times were obtained: τ(10) = 2.35 × 10(-5), τ(20) = 0.82 × 10(-4), τ(21) = 0.45 × 10(-3) s. The DFT calculations support the conclusion that the complexes C(1) and C(2) are the main species in the mixtures of CMPO with HP. They also agree with the NMR and FTIR observation that the main site to which H(3) O(+) is bound is the P=O group, whereas the amide group does not form a strong bond with the ion when excess water molecules are present.

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[15]Crown-5: An Unsymmetrical Bifacial Hydrogen-Bond Acceptor in Crystal Engineering

Cited by 31 publications

References 25 publications

The elusive [Ni(H₂O)₂(15-crown-5)]²⁺ cation and related co-crystals of nickel(II) hydrates and 15-crown-5

The elusive [Ni(H₂O)₂(15-crown-5)]²⁺ cation and related co-crystals of nickel(II) hydrates and 15-crown-5

NMR and theoretical study of the cooperative interaction of hydrated proton with dibenzo‐24‐crown‐8

Interaction of hydrated protons with octyl‐phenyl‐N,N‐diisobutylcarbamoylmethyl phosphine oxide (CMPO): NMR and theoretical study

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[15]Crown-5: An Unsymmetrical Bifacial Hydrogen-Bond Acceptor in Crystal Engineering

Cited by 31 publications

References 25 publications

The elusive [Ni(H2O)2(15-crown-5)]2+ cation and related co-crystals of nickel(II) hydrates and 15-crown-5

The elusive [Ni(H2O)2(15-crown-5)]2+ cation and related co-crystals of nickel(II) hydrates and 15-crown-5

NMR and theoretical study of the cooperative interaction of hydrated proton with dibenzo‐24‐crown‐8

Interaction of hydrated protons with octyl‐phenyl‐N,N‐diisobutylcarbamoylmethyl phosphine oxide (CMPO): NMR and theoretical study

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The elusive [Ni(H₂O)₂(15-crown-5)]²⁺ cation and related co-crystals of nickel(II) hydrates and 15-crown-5

The elusive [Ni(H₂O)₂(15-crown-5)]²⁺ cation and related co-crystals of nickel(II) hydrates and 15-crown-5