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

Abstract

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-

Syntheses and structures of [Ag(etu)3]2SO4 and [{Cu(etu)I}3] n (etu = ethylenethiourea): a new μ 3–S coordination mode for etu

“…[11,12]. The Cu-I t (terminal) distance (2.5897(6) Å ), which is comparable to that in the trigonally coordinated complex [Cu(petu) 2 ]I (petu ¼ Npropylethylenethiourea) [5], is shorter than Cu-I b (bridging) bonds (2.6230(5)- In IR spectra of 1, bands at 3260 (s), 1525 (s) cm À1 and 498 cm À1 can be assigned to (NH), (CN) and (CS), respectively. These three bands in free etu ligand are observed at 3240, 1520 and 507 cm À1 [18], respectively.…”

“…A series of silver(I) and copper(I) complexes with etu and its N-alkyl derivatives has been reported. The ligands display terminal monodentate thione-S, 2 -S and 4 -S bridging coordination modes, with the former being dominant; mononuclear complexes with trigonal [3][4][5][6][7][8][9][10], and tetrahedral [11] …”

63Cu NQR Studies of Three-coordinated Complexes of Cu(I) with an Isocyanide Ligand

“…Whereas we have extensively reported the 63 Cu NQR spectra of complexes of Cu(I) with ligands having nitrogen, sulphur, phosphorus, chlorine, bromine and iodine as the donor atom [1][2][3][4], we have only been able to observe resonances from one class of complexes with a ligand, the siloxyl group, having oxygen as donor [5], and until now have been unsuccessful in observing resonances from ligands with a carbon atom as donor. We may mention in this context our failure with the two-coordinated anionic complexes [ To our knowledge the only report of resonances from an organocopper complex concerns three aryl copper complexes with two-or three-coordinated copper atoms [6].…”

“…We have previously established [3], that the 63 Cu resonance frequencies of the three-coordinated complexes A 2 CuB are influenced by the A-Cu-A bond angle, 26. This behavior could be rationalized on the basis of a partial field-gradient model, and it was shown that both the sense and magnitude of the effect depends on the difference between the partial field-gradients, q a and q h , of A and B respectively, according to the equation…”

63Cu NQR Studies of Two-and Three-coordinated Complexes of Cu(I) with Siloxyl Ligands

“…We have previously established, [8], that the 63 Cu resonance frequencies of three-coordinated complexes A 2 CuB is influenced by the A-Cu-A bond-angle, 2 9. This behaviour could be explained on the basis of a partial field-gradient (pfg) model and it was shown that both the sense and the magnitude of the effect The frequencies of the three-coordinated species may be analysed with this equation, using the data for the analogous dimeric complex phosphine halides, IV, as reference compounds,…”