The <sup>63,65</sup>Cu NQR Spectra of Di-coordinated Cu<sup>I</sup> Cations with 2-Substituted Pyridine Ligands

Habiyakare, Augustin; Lücken, E. A. C.

doi:10.1515/zna-1990-3-406

Cited by 8 publications

(7 citation statements)

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“…The question remains, however, as to whether the reason for this difference resides in the structure of the isolated cation or in an effect arising from some detail of the crystal structure. Thus for the pyridine complexes the crystal structure [5] of (2,6-1utidine)2CuNO3 indicates that the nitrate anion is weakly coordinated to the Cu(I) cation and this increase in the coordination number of the metal ion reveals itself in a sharp drop in the resonance frequency to 32.650 MHz from the value of 41.275 NHz for the corresponding tetrafluoroborate [9]. A similar frequency lowering was observed [9] for other (2,6-1utidine)zCu + species with soft counter-anions such as CF3CO 2.…”

Section: Nqrmentioning

confidence: 95%

“…Thus for the pyridine complexes the crystal structure [5] of (2,6-1utidine)2CuNO3 indicates that the nitrate anion is weakly coordinated to the Cu(I) cation and this increase in the coordination number of the metal ion reveals itself in a sharp drop in the resonance frequency to 32.650 MHz from the value of 41.275 NHz for the corresponding tetrafluoroborate [9]. A similar frequency lowering was observed [9] for other (2,6-1utidine)zCu + species with soft counter-anions such as CF3CO 2. The crystal structure [2] of 1 reveals that while one of the fluorine atoms of the BF 4 anion is at a distance of 3.474 A the other three distances lie in the range 4.47 5.57A but for 6 and 9 the shortest Cu--F distance is more than 5A.…”

Section: Nqrmentioning

confidence: 95%

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63Cu NQR spectra of dicoordinated Cu(I) cations with imidazole and pyrazole ligands

Khajenhouri¹,

Motallebi²,

Lücken³

1995

Journal of Molecular Structure

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The 63Cu NQR spectra of five dicoordinated complex cations of Cu(I) with substituted imidazoles as ligands and six analogous complexes with substituted pyrazoles as ligands are reported. The structures of four of these complexes have been previously determined and the relationship of their 63Cu resonance frequency to the average Cu N bond length is compared to that of the analogous lutidine or collidine complexes. It is concluded that there are probably significant differences between the electronic structures of the pyridine complexes and those of the pyrazole or imidazole series.

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Section: Nqrmentioning

confidence: 95%

Section: Nqrmentioning

confidence: 95%

63Cu NQR spectra of dicoordinated Cu(I) cations with imidazole and pyrazole ligands

Khajenhouri¹,

Motallebi²,

Lücken³

1995

Journal of Molecular Structure

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“…Fig 6. The 63Cu NQR frequencies (in MHz at 298 K) and SCu-S bond angles of three-co-ordinated complexes of copper(r) chlorides (O), bromides (0) and iodides(7) with thione ligands…”

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confidence: 99%

Copper-63 nuclear quadrupole resonance frequencies and molecular geometries of three-co-ordinate complexes of copper(I) halides with N-alkylimidazolidinethione and thiazolidinethione ligands

Ramaprabhu¹,

Lücken²,

Bérnardinelli³

1995

J. Chem. Soc., Dalton Trans.

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The crystal structures of seven three-co-ordinated complexes of copper( I) halides with thione ligands, [CuXL,], where L = 1,3-thiazolidine-2-thione and X = CI or Br, L = N-ethylimidazolidine-2-thione and X = Br, L = N-isopropylimidazolidine-2-thione and X = CI or Br, and L = N-propylimidazolidine-2thione and X = CI or I have been determined. In all complexes, the copper lies in a trigonal-planar environment and the thiazolidine or imidazolidine rings show n o major distortion from planarity. Owing to the presence of hydrogen bonding involving H[N(2)], or H[N(02)], and the halogen atom all complexes adopt a W-shaped conformation. The 63Cu NQR frequencies of these complexes, together with those of two other similar complexes whose structures were already available, depend, for a given halide, on the S-Cu-S bond angle, a decrease in angle producing an increase in resonance frequency: v, , = 28.7 -0.544A8 and v,, = 26.9 -0.229A8 MHz, where A8 is the difference between the S-Cu-S bond angle and 120". This behaviour has been rationalized in terms of a partial field-gradient model of the resonance frequencies.We have previously reported studies of the 63Cu NQR spectra of Cu' complexes with a variety of charges, co-ordination numbers and ligand~.'-~ The 63Cu NQR spectra of the threeco-ordinated complexes, [CuXL,], of N-alkylimidazolidine-2thiones (L) with cuprous halides '9, led us to believe that there was a possible correlation between the L-Cu-L bond angle and the resonance frequency for the complex of a given halide. To investigate this point further we have determined the crystal structures of seven complexes of this type: L = 1,3-thiazolidine-2-thione, X = C11 or Br 2; L = N-ethylimidazolidine-2-thione, X = Br 5; L = N-isopropylimidazolidine-2-thione, X = Cl 6 or Br 7; and L = N-propylimidazolidine-2-thione, X = C18 or I 9. The crystal structures of two other complexes [CuClL,] (L = N-methylimidazolidine-2-thione 3 or N-ethylimidazolidine-2-thione 4) were already available. ' ' 3 'These results confirm the existence of the correlation and we report here the results of this study. ExperimentalPreparations.-The preparations of the ligands and the Cu' complexes [CuXL,] have been reported previously. ' , 2 Crystals suitable for X-ray crystallographic studies were obtained by recrystallization from 1,Zdichloroethane (1, 2, 5 and 9), or acetone (6 and 7).X-Ray CrystaZlography.--Cell parameters and reflection intensities were measured at room temperature on automatic four-circle diffractometers with graphite-monochromated Mo-

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“…In the course of an investigation of the 63*65Cu NQR resonance frequencies and crystal structures of two-co-ordinated copper (1) cations with hindered pyridine ligands we discovered methods for the preparation of the analogous three-coordinated cations. The crystal structure of tris(2-methylpyridine)copper(I) perchlorate was reported in 1972,j but although three-co-ordinated copper(1) complexes are not uncommon they are usually neutral species, and we are not aware of any reports of the preparation or structures of any other such complex cations with substituted pyridine ligands.…”

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Nuclear quadrupole resonance and crystallographic studies of three-co-ordinated copper(I) cations with alkylpyridine ligands

Habiyakare¹,

Lücken²,

Bérnardinelli³

1992

J. Chem. Soc., Dalton Trans.

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The preparation and 63,65Cu NQR resonance frequencies of fourteen three-co-ordinated complex cations of copper(I) with alkylpyridine ligands are reported. Crystal structures of seven of these have also been determined. The complexes show a wide variety of symmetries but in none does the copper atom lie on an ideal three-fold axis. In most the copper lies in an essentially trigonal-planar environment but with at least two of the pyridine ligands twisted well out of the plane containing the copper and the three nitrogen atoms. In most cases one of the N–Cu–N bond angles is significantly greater than 120° while the length of the opposing bond is significantly greater than that of the two bonds that form this angle. All the NQR frequencies at 77 K are in the neighbourhood of 45 MHz, with the exception of that of the complex with 3,5-dimethylpyridine, the only ligand without at least one alkyl substituent ortho to the nitrogen atom, where the frequency at 77 K is 40.471 MHz. This difference results from the axial co-ordination of both the PF6 anions to the copper cation

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The ^63,65Cu NQR Spectra of Di-coordinated Cu^I Cations with 2-Substituted Pyridine Ligands

Cited by 8 publications

References 3 publications

63Cu NQR spectra of dicoordinated Cu(I) cations with imidazole and pyrazole ligands

63Cu NQR spectra of dicoordinated Cu(I) cations with imidazole and pyrazole ligands

Copper-63 nuclear quadrupole resonance frequencies and molecular geometries of three-co-ordinate complexes of copper(I) halides with N-alkylimidazolidinethione and thiazolidinethione ligands

Nuclear quadrupole resonance and crystallographic studies of three-co-ordinated copper(I) cations with alkylpyridine ligands

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The 63,65Cu NQR Spectra of Di-coordinated CuI Cations with 2-Substituted Pyridine Ligands

Cited by 8 publications

References 3 publications

63Cu NQR spectra of dicoordinated Cu(I) cations with imidazole and pyrazole ligands

63Cu NQR spectra of dicoordinated Cu(I) cations with imidazole and pyrazole ligands

Copper-63 nuclear quadrupole resonance frequencies and molecular geometries of three-co-ordinate complexes of copper(I) halides with N-alkylimidazolidinethione and thiazolidinethione ligands

Nuclear quadrupole resonance and crystallographic studies of three-co-ordinated copper(I) cations with alkylpyridine ligands

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The ^63,65Cu NQR Spectra of Di-coordinated Cu^I Cations with 2-Substituted Pyridine Ligands