摘要:

J. CHEM. SOC. DALTON TRANS. 1989 1639 Lewis-base Adducts of Group I 1 Metal(i) Compounds. Part 58.' Syntheses, X-Ray Structures, and Far-infrared Spectra of the Novel [CuX,(bidentate ligand)]- (X = CI or Br) Anion Salts of the [Cu(dpa),]+ Cation and the Dimeric Iodide [(dpa)Cul,Cu(dpa)] * [dpa = di(2-pyridyl)amine] Graham A. Bowmaker Department of Chemistry, University of Auckland, Auckland, New Zealand Peter C. Healy School of Science, Griffith University, Nathan, Queensland 47 I I , Australia David L. Kepert, John D. Kildea, Brian W. Skelton, and Allan H. White Department of Physical and Inorganic Chemistry, University of Western Australia, Nedlands, W.A. 6009, A ustralia Reaction of copper(i) halides (CuX, X = CI, Br, or I) in acetonitrile solution with di(2- pyridyl)amine(dpa) yields 1 : 1.5 adducts with the chloride and bromide, a 1 : 1 adduct with the iodide, and a 1 : 2 adduct with the chloride.The compounds have been characterized by spectroscopic and single-crystal X-ray methods. The 1 : 1 iodide is a dimer, [(dpa)Cul,Cu(dpa)], of a type familiar with other bidentate nitrogen base ligands, but the 1 : 1.5 complexes are ionic, formulated as [Cu(dpa),] + [Cu(dpa)X,] -, containing the first structurally characterized [Cu(dpa),] +- cations and [CuX,(bidentate ligand)] - anions, while the 1 : 2 chloride is [Cu(dpa),] 'CI-. In the [Cu(dpa),] + cation mean CU-N is ca. 2.00 A, while in the [Cu(dpa)X,] - anions Cu-N is ca. 2.05 A and Cu-CI and Cu-Br 2.369(2), 2.302(2) and 2.490(6), 2.439(6) A respectively. The dpa ligand in all cases is essentially planar.The far i.r. spectra of the anions show bands at 21 4 cm-' (chloride) and 160 cm-' (bromide) which can be assigned to the asymmetric stretching mode of the CuX, unit. In previous papers in the present series we have recorded studies of the complexes formed with the copper(1) halides, CuX (X = C1, Br, or I), with bidentate ligands, L. From neat N,N,N',N'-tetramethylethylenediamine (tmen), 1 : 1 complexes have been obtained, the iodide being a dimer, as is the bromide [(tmen)CuX,Cu(tmen)], while the chloride disproportionates to ionic [Cu(tmen),] + [CuCl,] -. With 1,lO-phenanthroline (phen) (from acetonitrile as solvent), 1 : l iodide3 and bromide4 adducts were obtained; the iodide again is a dimer, but the bromide is ionic, [(phen)CuI,Cu(phen)] and [Cu(phen),] -+ [CuBr,] - respectively.With 2,9-dimethyl-l,10- phenanthroline (dmphen) substituent effects come into play and the bromide and iodide are dimeric [(dmp)CuX,Cu(dmp)] while the chloride is monomeric, [Cu(dmp)Cl]. The ligand tmen is a ligand of larger bite than phen; in the present paper we examine the nature of complexes obtained by the reaction of an N,N-bidentate of even larger bite, di-(2-pyridyl)amine (dpa), with the copper(1) halides. Structural studies, reported here, show the iodide to be a 1: 1 dimer, consistent with all other bidentate nitrogen base-copper(1) iodide complexes studied to date. The chloride and bromide complexes, however, are ionic compounds containing the [Cu(dpa),] + cation and novel [Cu(N,N-bidentate ligand)X,] - anions, characterized here by X-ray structure determination and far-i.r.spectroscopy. The 'parent' [Cu(dpa),] +C1- has also been characterized. Experimental Synthesis.-[Cu(dpa),] +C1-. The ligand dpa (0.5 g) was added to a solution of CuCl (0.2 g) in degassed CH3CN (10 cm3) under argon. Orange crystals of the compound precipitated immediately, m.p. (decomp.) > 150 "C (Found C, 54.1; H, 4.0; N, 19.0. Calc. for C2,H,,ClCuN,: C, 54.4; H, 4.1; N, 19.0%). [Cu(dpa),]+[Cu(dpa)Cl,] -. The ligand dpa (0.35 g) was added to a solution of CuCl (0.5 g) in degassed acetonitrile (40 cm3) under argon. This resulted in mixed red and yellow precipitates which redissolved on warming in a water-bath to give a clear yellow solution. This was allowed to cool slowly, then stored at -20 "C overnight to give well formed yellow crystals of the complex, m.p.(decomp.) > 150 "C (Found: C, 50.7; H, 3.8; N, 17.9. Calc. for C3,H,,Cl,Cu,N,: C, 50.6; H, 3.8; N, 17.7%). [Cu(dpa),] +[Cu(dpa)Br,] -. The ligand dpa (0.24 g) was added to a solution of CuBr (0.2 g) in degassed acetonitrile (20 cm3) resulting momentarily in a clear orange solution, followed by immediate crystallization of yellow crystals of the complex. Addition of an excess of dpa to the solution did not result in crystallization of orange crystals of [Cu(dpa),] +Br- by analogy with the chloride sample; m.p. (decomp.) > 150 "C (Found: C, 45.2; H, 3.4; N, 15.9. Calc. for C,,H,,Br,Cu,N,: C, 45.0 H, 3.4; N, 15.8%). [(dpa)CuI,Cu(dpa)]. The ligand dpa (0.22 g) was added to a solution of CuI (0.25 g) in degassed acetonitrile (20 cm3) to give a yellow solution from which yellow crystals of the complex formed as its acetonitrile solvate, m.p.(decomp.) > 150 "C (Found: C, 35.4; H, 2.9; N, 13.8. Calc. for CIZHl2CuIN4: C, 35.8; H, 3.0; N, 13.9%). Samples were sealed in capillaries for the crystallographic work. Far-i.r. Spectra.-These were recorded at ca. 298 K as petroleum jelly mulls between Polythene plates on a Digilab FTS-60 Fourier-transform Spectrometer employing a FTS-60V vacuum optical bench and a 6.25-pm mylar beam splitter. * Supplementary data available: see Instructions for Authors, J . Chern. Soc., Dalton Trans., 1989, Issue 1 , pp. xvii-xx.1640 J. CHEM. SOC. DALTON TRANS. 1989 Table 1. Non-hydrogen atom co-ordinates for [Cu(dpa),] +C1- Ligand A A \ f- Atom X Y 2.0.506 28(5) 0.470 6(3) 0.338 O(3) 0.318 5(3) 0.439 O(4) 0.577 7(4) 0.587 O(3) 0.292 6(3) 0.181 7(3) 0.030 O(3) 0.008 O(4) 0.103 2(4) 0.249 2(4) 0.2 13 O(2) 0.940 94(7) 0.898 97(2) 1 .OOO 4( 1) 1.041 3(2) 1.1 12 7(2) 1.141 9(2) 1.100 9(2) 1.031 5(2) 0.896 l(1) 0.949 4(2) 0.941 6(2) 0.875 7(2) 0.818 4(2) 0.831 3(2) 1.016 2(1) 0.145 lO(4) 0.247 77(4) 0.162 6(2) 0.124 O(2) 0.065 9(2) 0.051 l(3) 0.092 l(3) 0.145 4(3) 0.239 3(2) 0.184 l(2) 0.170 l(2) 0.211 3(3) 0.265 6(3) 0.277 l(2) 0.138 3(2) 0.076 17(6) X 0.532 O(3) 0.666 O( 3) 0.684 6(3) 0.558 l(4) 0.41 6 9(4) 0.409 6(3) 0.713 4(3) 0.814 6(3) 0.946 7(4) 0.976 9(5) 0.877 l(5) 0.749 4(4) 0.793 7(2) Ligand B Y 2 0.788 9( 1) 0.749 5(2) 0.679 2(2) 0.646 8(2) 0.684 5(2) 0.754 7(2) 0.896 9( 1) 0.836 7(2) 0.832 4(2) 0.891 7(2) 0.955 6(2) 0.955 4(2) 0.776 4( 1) 0.198 8(2) 0.240 6(2) 0.193 9(2) 0.107 O(3) 0.067 l(3) 0.1 13 2(3) 0.383 4(2) 0.408 7(2) 0.510 3(3) 0.585 O(3) 0.558 l(3) 0.459 O(3) 0.334 3(2) Structure Determinations.-Unique data sets were measured within the specified 20,,,.limits at ca. 295 K using Syntex P2, and Enraf-Nonius CAD-4 four-circle diffractometers, fitted with monochromatic Mo-K, radiation sources (h = 0.7106, A) and operating in conventional 20-0 scan mode. N Independent reflections were measured, No with I > 3 4 0 being considered 'observed' and used in the large-block least-squares refinement after gaussian absorption correction. Anisotropic thermal parameters were refined for the non-hydrogen atoms; (x, y , z, Uis& were included constrained at estimated values. Residuals at convergence are conventional R,R' on IFI, statistical weights derived from 02(0 = 02(Idiff) + 0.0005 04(rdiff) being used.Neutral atom complex scattering factors were employed; computation used the XTAL 83 program system implemented by S. R. Hall on a Perkin-Elmer 3240 computer. The structures are illustrated in Figures 1 and 2 (also showing atom labelling); atomic co-ordinates are given in Tables 1-3. Crystal data. [Cu(dpa),]+Cl-, C20H,8CICUN6, hf = 441.4, monoclinic, space group P2,/c (Cz,,, no. 14), a = 9.676(2 b = 16.823(6), c = 13.642(6) A, p = 117.15(3)', U = 1976 i3. D, (2 = 4) = 1.48 g ~ m - ~ , F(000) = 904, pMo = 11.9 cm-', specimen 0.13 x 0.31 x 0.30 mm, = 1.16, 1.26, 20,,,. = 50°, N = 3 454, No = 2 527, R = 0.034, R' = 0.038.[Cu(dpa),] + [Cu(dpa)Cl, J -, C3,H,,C1,Cu,N9, M = 7 1 1.6, monoclinic, space group P2,/n [Ci,,, no. 14 (variant)], a = 9.582(4 b = 22.532(8), c = 13.893(5) A, p = 91.58(3)", U = 2 999 k3, D, (Z = 4) = 1.58 g cme3, F(OO0) = 1448, pMo = 15.6 cm-', specimen cuboid, 0.20 mm, = 1.30, 1.35, [Cu(dpa),] +[Cu(dpa)Br,] -, C30H,,Br2Cu2N,, M = 800.5, monoclinic, space group P2,/n, a = 9.681(2), b = 23.104(8), 1.71 g ~ m - ~ , F(OO0) = 1 592, pMo = 39 cm-', specimen 0.30 x 0.07 x 0.07 mm, A2in.,max. = 1.28, 1.32, 28,,,. = 40°, N = 2 905, No = 1230, R = 0.084, R' = 0.067. [(dpa)CuI,Cu(dpa)]-2CH3CN, C24H24C~212N8, M = 805.4, 2e,,,, = 400, N = 3 005, N~ = 1994, R = 0.047, R' =0.033. c = 13.871(4) A, p = 90.37(2)', U = 3 102 A3. D, (2 = 4) = orthorhombic, space group Pcab [oil, no.61 17.575(3), b = 12.946(2), c = 12.328(4) A, U 2e,,,, = 450, N = 2 202, N, = 1 596, R = 0.043, R' = 0.030. (2 = 8) = 1.91 g ~ m - ~ , F(000) = 1552, pMo = 39 cm-', specimen 0.18 mm polyhedral spheroid, A:in.,max. = 1.5 1, 1.66, Abnormalfeatures. Data for the bromide were very weak and limited in scope and would only support meaningful refinement of isotropic thermal parameters for C and N. For the iodide, difference-map artefacts were successfully modelled and refined in terms of a fully occupied acetonitrile solvate molecule; the nitrogen atom was assigned on the basis of thermal parameter behaviour and methyl hydrogen atoms subsequently inferred from difference maps. These results are consistent with the analysis. Additional material available from the Cambridge Crystal- lographic Data Centre comprises H-atom co-ordinates, thermal parameters, and remaining bond distances and angles.Discussion Results of the single-crystal structure determinations of the adducts of copper(1) chloride, bromide, and iodide with dpa are consistent with their formulation as 1 : 2, 1 : 1.5, 1 : 1.5, and 1 : 1 complexes respectively as above, the iodide being an acetonitrile monosolvate. In the iodide the complex is found to be of the dimeric [LCuI,CuL] form, familiar already for the examples L = tmen, phen, or dmphen; in the present case, one half of the dimer (with associated solvent) is the asymmetric unit of the structure, the other half being generated by a crystallographic inversion centre. Molecular N,CuI,CuN, core geometries are given in Table 4, in comparison with those for the above examples, showing a number of features of interest; we exclude from our commentary the dmphen example where substituent effects already discussed in detail el~ewhere,~ cause a gross asymmetry in the structure.First, we note that, despite considerable variation in parameters relating to the nitrogen atoms, the Cu1,Cu core geometry is remarkably insensitive to such changes; further comparison with a summary of L',CuI,CuL', core geometries (L' = monodentate N-base ligand without a 2 substituent, oiz. pyridine or 3,Sdimethylpyridine) given else- where7 shows a similar insensitivity to whether the ligand L is bidentate or replaced by L', = two monodentate ligands. Perturbation of these geometries, however, is readily achieved in both cases by incorporation of a 2-methyl substituent in the ligands of either type.In the present system, in respect of the nitrogen bases, we observe a considerable change in ligand 'bite,' as measured by the N-Cu-N angle, increasing from phen (ca. 80') to tmen ca. 84") to dpa (ca. 95'); this is not paralleled by a corresponding monotonic variation in Cu-N distance, that for the present system being by far the shortest (mean 2.04 A) and that for the aliphatic tmen system the longest (mean 2.17, A). The dpa ligand is substantially planar (not only in the present iodide, but also the chloride and bromide complexesJ. CHEM. SOC. DALTON TRANS. 1989 1641 Table 2. Non-hydrogen atom co-ordinates for [C~(dpa)~]+[Cu(dpa)X~]- (X = C1 or Br) Chloride Bromide I A 3 f X X Y 1 7 Y Z 0.229 9(2) 0.136 9(2) 0.095 4( 1) -0.111 4(6) -0.164 3(8) -0.309 2(8) -0.393 2(8) - 0.340 2(9) - 0.200 O(8) 0.140 O(6) 0.051 2(8) 0.093 4(10) 0.228 l(10) 0.318 2(9) 0.271 2(9) -0.085 l(6) 0.127 85(8) 0.064 09(8) 0.060 67(4) 0.052 6(3) 0.004 7(3) 0.002 O(4) 0.047 2(4) 0.096 3(4) 0.096 5(3) -0.023 O(2) -0.059 2(3) -0.114 3(3) -0.132 3(3) -0.095 3(3) -0.041 8(3) -0.042 3(2) 0.102 6(1) 0.356 8( 1) 0.192 84(8) 0.152 9(4) 0.107 3(5) 0.085 3(6) 0.109 3(6) 0.155 8(6) 0.177 4(6) 0.147 2(4) 0.098 9(5) 0.067 4(6) 0.086 6(6) 0.135 7(6) 0.164 6(6) 0.080 l(4) 0.246 2(4) 0.128 4(3) 0.095 5(4) -0.115(2) -0.157(3) -0.31 l(3) -0.392(3) -0.326(3) - 0.194(3) 0.132(2) 0.048(3) 0.080( 3) 0.21 l(4) 0.299(3) 0.269(3) -0.091(2) 0.126 l(2) 0.065 2(2) 0.058 9(2) 0.056( 1) 0.009( 1) 0.005(1) 0.051(1) 0.101( 1) 0.102( 1) - 0.022( 1) - 0.056( 1) - 0.1 13( 1) -0.132( 1) -0.101 (1) - 0.040( 1) - 0.045( 1) 0.100 8(3) 0.367 3(3) 0.193 l(3) 0.148(2) 0.089(2) 0.116(2) 0.163(2) 0.173(2) 0.15 l(2) 0.105(2) 0.077(2) 0.090(2) 0.144(2) 0.164(2) 0.083(2) O.lll(2) Cation c u 0.794 8( 1) 0.347 68(4) 0.145 28(8) 0.801 9(5) 0.344 7(2) 0.145 4(3) 0.816 5(6) 0.709 l(7) 0.728 3(8) 0.860 7(8) 0.972 3(8) 0.946 2(8) 0.584 8(6) 0.511 5(7) 0.364 4(8) 0.297 2(8) 0.375 l(8) 0.515 5(8) 0.571 9(6) 0.435 3(2) 0.472 4(3) 0.532 l(3) 0.554 8(3) 0.517 8(3) 0.459 3(3) 0.348 3(2) 0.398 7(3) 0.397 9(3) 0.345 2(3) 0.293 2(3) 0.296 7(3) 0.454 O(2) 0.139 6(4) 0.124 O( 5) 0.103 3(6) 0.099 O(6) 0.116 l(5) 0.134 7(6) 0.142 O(4) 0.135 4(5) 0.133 3(5) 0.140 4(6) 0.147 8(6) 0.147 5(5) 0.131 2(4) 0.825(2) 0.732(3) 0.745( 3) 0.8 70( 3) 0.975(3) 0.956(3) 0.599(2) 0.526(3) 0.376(3) 0.3 19(3) 0.381(3) 0.522(3) 0.595(2) 0.429(1) 0.469( 1) 0.526( 1) 0.549( 1) 0.5 lO(2) 0.452(1) 0.348( 1) 0.399( 1) 0.397( 1) 0.344( 1) 0.293( 1) 0.300(1) 0.450( 1) 0.144(2) 0.1 1 l(2) 0.1 1 l(2) 0.1 3 l(2) 0.123(3) 0.139(2) 0.145(2) 0.140(2) 0.132(2) 0.133(2) 0.143( 2) 0.142(2) 0.128(2) 0.886 8(6) 0.986 4(7) 1.070 3(7) 1.044 9(8) 0.936 6(8) 0.862 7(8) 0.899 l(6) 0.982 O(7) 1.037 l(8) 1.010 2(8) 0.928 6(8) 0.875 O(8) 1.017 6(6) 0.307 3(2) 0.267 3(3) 0.250 4(2) 0.273 5(3) 0.313 8(3) 0.328 7(3) 0.299 3(2) 0.253 6(3) 0.216 8(3) 0.228 7(3) 0.277 3(3) 0.310 2(3) 0.239 4(2) 0.034 5(4) 0.044 l(5) - 0.030 8( 5) -0.134 3(5) -0.055 5(6) -0.120 7(5) 0.246 O(4) 0.225 l(5) 0.297 5(5) 0.389 9(5) 0.413 8(5) 0.339 8(5) 0.131 8(4) 0.894(2) 0.993(3) 1.087(2) 1.056(3) 0.944( 3) 0.876(3) 0.907(2) 0.990( 3) 1.047(3) 1.023(2) 0.94 l(3) 0.891(3) 1.028(3) 0.306( 1) 0.265( 1) 0.250( 1) 0.274( 1) 0.312(1) 0.326( 1) 0.298( 1) 0.254( 1) 0.229( 1) 0.279( 1) 0.308( 1) 0.24 1 (1) 0.221 (1) 0.032(2) 0.042(2) - 0.036(2) -0.116(2) - 0.143(2) - 0.056(2) 0.242( 2) 0.224(2) 0.297(2) 0.390( 2) 0.414(2) 0.342(2) 0.129(2) discussed below), with no pyridine-pyridine interplanar dihedral angle exceeding 18" and mean (centra1)N-C distances in the more recisely determined examples (chloride, iodide) being 5 1.40 1.The overall dimer configuration is of considerable interest. Systems L',CuX,CuL', have been synthesized and structurally characterized for all X, but full sequences for specific ligands are only available for the hindered L' = 2-methyl- and 2,4- dimethylpyridine.For the former, trends in the Cu Cu distance are erratic; for the latter, the three compounds are isostructural and Cu Cu increases monotonically from 2.995(3) (Cl), 3.091(3) (Br), to 3.140(3) A (I), although it is not clear that in the absence of hindrance in the base this is necessarily a trend to be expected. In particular we note that for the bidentate ligand 2,9-dimethyl-l,lO-phenanthroline (dmphen) the isostructural pair [(dmp)CuX,Cu(dmp)], X = Br or I, exhibit a reverse trend with Cu 9 Cu 3.097(1) and 3.024(2) A respectively, although ligand strain appears greater in the bromide. For whatever reason, for the sequences of bidentate bases so far studied, dimers are generally established for the iodide, sometimes for the bromide, and never for the chloride, ligand disproportionation or monomer formation occurring and reducing the average co-ordination number of the copper atom.Thus for L = tmen the chloride is [CuL,]' [CuCl,] -, for phen the bromide is [CuL,] + [CuBr,] -, and for dmphen the chloride is [CuLCI]. In examining factors which1642 J. CHEM. SOC. DALTON TRANS. 1989 Table 3. Non-hydrogen atom co-ordinate for [(dpa)CuI,Cu(dpa)] Atom X Y z 0.449 60(3) 0.141 96(4) 0.083 07(5) 0.564 68(6) 0.019 43(8) 0.047 42(9) 0.624 2(4) -0.030 3(5) 0.178 4(5) 0.698 3(5) -0.008 3(6) 0.196 l(7) 0.737 4(5) -0.047 6(7) 0.285 9(8) 0.701 9(6) -0.109 2(8) 0.357 l(8) 0.626 8(6) -0.136 7(8) 0.338 O(8) 0.592 3(5) -0.096 l(7) 0.250 6(9) 0.721 8(5) 0.108 8(6) 0.031 5(7) 0.651 7(4) 0.108 2(5) -0.012 4(5) 0.780 4(5) 0.168 8(6) -0.013 8(8) 0.766 l(5) 0.222 8(7) -0.104 2(9) 0.695 6(6) 0.220 5(7) -0.151 9(8) 0.640 5(5) 0.162 l(7) -0.102 3(7) 0.738 9(4) 0.054 O( 5 ) 0.125 6(6) Acetonitrile solvent N(O) 0.908 2(5) 0.008 6(8) 0.127 O(8) C(0 1) 1.016 O(6) -0.122 7(8) 0.1194(9) C(0) 0.957 9(7) -0.050 8(10) 0.123 2(8) Figure 1.Projections of [(dpa)CuI,Cu(dpa)]: (a) perpendicular to the Cu1,Cu plane; (b) perpendicular to the Cu . - . Cu line, in the Cu1,Cu plane. 20% Thermal ellipsoids are shown for the non-hydrogen atoms, together with atom labelling. Hydrogen atoms have an arbitrary radius ofO.l A may assist in explaining why only the iodide is dimeric for dpa, it is of interest to note [Figure l(b)] the ligand disposition; for L = phen, the dimer [(phen)CuI,Cu(phen)] displayed in Figure 1 of ref.3 is found to be quite devoid of ligand strain, so much so that the Cu1,Cu core is non-planar. The increased bite of the dpa ligand (uis-u-uis phen) in the present examples Figure 2. (a) Unit-cell contents of [Cu(dpa),] + [Cu(dpa)Cl,] projected down a; (h) the cation, projected down a pseudo-two-fold axis; (c) the anion, projected normal to the ligand plane means that this situation no longer obtains, Figure l(b) strongly being suggestive of the evasion of interligand hydrogen interactions across the core, consistent with the H(16) H(26) estimate of 2.6 A and correlating with the asymmetry in the Cu-I distances.In this context, our inability to obtain the chloride and bromide as 1 : 1 dimers is not surprising. Chloride and bromide structures consistent with an ionic formulation, are, surprisingly, not the 1 : 1 stoicheiometry of [Cu(dpa),]+[CuX,]-, which might be expected on the basis of the above precedents and which we have been unable to obtain (at least from acetonitrile solution), but, rather, 1 : 1.5 stoicheiometry consistent with [Cu(dpa),] +[Cu(dpa)X,] -, and in the case of the chloride also 1:2, [Cu(dpa),]+CI-, in which both copper atoms retain a co-ordination number of four. The cation is the first of this type to be structurally character- ized with dpa as a bidentate ligand; we compare it withJ. CHEM. SOC. DALTON TRANS. 1989 1643 Table 4.Molecular N,CuI,CuN, core geometries (iodide) (distances in A, angles in "). Values pertain to [LCuI,CuL] (L = symmetrical N,N- bidentate ligand) systems cu-I cu-I' Cu-N( 1 ) Cu-N(2) c u - * c u I...I L = dpa" 2.608( 1) 2.649( 1) 2.029(7) 2.606(1) 4.566( 1) 2.05 l(7) - tmen 2.605(5) 2.596(5) :::::;;} 2.566(4) 4.491(3) phen 2.589( 1) 2.078(6) 2.609(2) 4.454(2) - 2.632( 1) - 2.103(6) dmphen ' 2.673( 1) 2.563(1) 2.094(6) 2.092(5) 3.024(2) 4.276( 1) N( 1 )-Cu-N(2) 94.6(3) 84.4(8), 82.9( 11) 80.8(2), 79.7(2) 80.4( 2) I-cu-I' 120.58(4) 1 19.3( l), 1 1 9 3 1) 118.53(4), 116.85(4) 109.48(4) cu-I-CU' 59.42(3) 59.1(1), 59.1(1) 59.96(4), 60.3 8(4) 70.52(4) I-Cu-N( 1) 1 17.3(2) I-Cu-N(2) 1 07.3( 2) I'-Cu-N( 1) 106.4(2) I '-C u-N(2) 1 07.1 (2) " This work. Ref. 2. Ref.3. Table 5. Cation core geometries (distances in A, angles in "); values pertain to [CuLJ' (L = symmetrical N,N-bidentate ligand) systems Cu-N(A 1) CU-N(A2) Cu-N(B 1) Cu-N( B2) CCu(dpa),I + " CCNphen),l+ L A r [C~(tmen),]+~ > 2.003(2) 1.988(5) 1.97(2) 2.15(1) 2.045(8) 2.006(8) 2.01 8(3) 2.01 l(6) 1.96(2) 2.15(1) 2.07 l(5) 2.022(3) 2.0 1 3 (6) 2.0 1 (2) 2.16(1) 2.053(9) 2.0 14( 2) 2.018(5) 2.00(2) 2.13(1) N(A I )-Cu-N(A2) 95.0( 1) 95.6(2) 94.1(9) 86.0(4) 8 1.4(3) 82.2(3) N(B 1 ECu-N(B2) 93.8(1) 93.8( 2) 93.5(9) 8 5.3(4) 80.9(3) N(A lkCu-N(B1) 127.1(1) 1 1 1.8(2) 112.1(9) 122.9(4) N(A l)-Cu-N(B2) 1 12.q 1) 121.0(2) 118.9(9) 121.6(4) 109.7(3) 115.8(3) N(A2)-Cu-N(B2) 128.1(1) 119.7(2) 122.3(9) 122.5( 5) N(A~)-CU-N(B 1) 103.7( 1) 1 16.4(2) 117.6(9) 1 23.1 (4) - 144.7(2) - 146.0( 3) ' Values are for [Cu(dpa),]+Cl- and [Cu(dpa),]'[Cu(dpa)X,]- (X = C1 or Br) respectively.Ref. 2. ' Ref. 4; the two values are for the perchlorate and dibromocuprate respectively. For data from ref. 4, the atom designation has been set in conformity with the present system. Table 6. Anion core geometries (distances in A, angles in ") cu-X( 1 ) cu-X(2) Cu-N( 1 I ) Cu-N( 12) Chloride Bromide 2.369(2) 2.490(6) 2.302(2) 2.439(6) 2.051(6) 2.13(2) 2.039(6) 1.99(2) X( 1)-Cu-X(2) 114.86(8) 113.5(2) X( 1)-Cu-N( 11) 116.7(2) 115.6(6) X( l)-Cu-N( 12) 107.7(2) 109.2(6) X(2)-Cu-N( 11) 114.2(2) 114.2(6) X(2)-Cu-N( 12) 107.9(2) 108.7(7) N( 1 1 )-Cu-N( 12) 92.5(2) 9339) [Cu(tmen),]+ and [Cu(phen),]+ in Table 5. As might be expected, the hierarchy of 'bite' angles found for the ligands in this sequence remains as established above for their iodide complexes; a similar hierarchy of Cu-N distances is also found, shorter overall in the dpa adducts by perhaps 0.02 A.The anions (Table 6) are novel; we are aware of no other examples for monodentate N-base [CuL',X,] - or bidentate [CuLX,] - stoicheiometry. The Cu-X distances in [CuCl,] - and [CuBr,]- are typically 2.0863 and 2.21, A4 respectively, by comparison with the present (mean) values of 2.33 and 2.46, A. The angle X-Cu-X in the present species is somewhat above the tetrahedral value, as might be expected in consequence of being opposed to a ligand bite angle well below it, and comparable, as is the Cu-N distance, to the value of the iodide dimer. The N-Cu-N angles correspond to a normalized bite of 1.45, and the X-Cu-X angles of 114.9 (Cl) and 113.5" (Br) correspond to effective bond-length ratios R(X/N) of 0.89(Cl) and 0.91(Br) in agreement with expected values for a halide ligand compared with an unchanged bidentate ligand.' One final feature worthy of note is the presence of strong hydrogen-bonding interactions involving the amine hydrogen.In [Cu(dpa),] +C1-, C1 H(3A)(1 + x,y - 1, z) is 2.2, A and C1 H(3B)(2 - x, 4 + y , 4 - z ) 2.1, 8, is very short; comparable effects are seen in [Cu(dpa),] + [Cu(dpa)Cl,] -: z), and H(3)(anion) Cl(l)(Z, j j , 2) are 2.1 1, 2.30, and 2.37 A, with counterparts in the bromide of 2.4,, 2.4,, and 2.4, A. The iodide appears devoid of close contacts. H(3B) C1(1)( 1 + X, y , Z), H(3A) C1(2)(4 - X, + y , 4 - Far-i.r.Spectra.-The far-i.r. spectra of the 1 : 1.5 chloro- and bromo-complexes are shown in Figure 3. Halogen-sensitive bands occur in the region below 200 cm-'. Two ~(CU-X) bands are expected in the far4.r. region. Assuming an idealized C,, structure for the non-linear CuX, unit, these arise from the symmetric ( A , ) and asymmetric ( B , ) stretching modes. In the closely related anionic complex [Cu(PPh,)Br,] - these bands have been assigned at 195 ( B , ) and 150 cm-' ( A , ) . 9 We have recently shown that ~(CU-X) can be empirically correlated with the Cu-X bond length r in a range of CuX complexes which contain a single terminal Cu-X bond." For CuCl and CuBr complexes this relationship may be represented by equation (1)1 644 96 J. CHEM.SOC. DALTON TRANS. 1989 aJ t f VI LI Q 4 09 ( b ) 409 400 3 00 200 100 Wavenumber I cm-' Figure 3. Far4.r. spectra (5Cb-450 cm-') of the [Cu(dpa)X,]- (X = C1 or Br) complexes Table 7. Observed and calculated metal-halogen stretching frequencies v(Cu-X)/cm- ' - Complex Obs. Calc. f,/N m-' [Cu(PPh,)Br,] - a 195 189 (Bl) 60 [Cu(dpa)Br,] - 160 165 ( B , ) 44 [Cu(dpa)Cl,] - 214 216 ( B , ) 54 133 ( A , ) 188 ( A , ) - - Ref. 9. * This work. where b = 13 800 and 18 000 and m = 4.9 and 5.2 for X = C1 and Br respectively. The present complexes contain two halogen atoms terminally bound to the same copper atom, and so are significantly different in structure to those for which equation (1) was obtained. However, we have noted that the wavenumber of the more intense, higher-frequency (B,) v(Cu-Br) mode of the complex [Cu(PPh,)Br,] - is predicted very well by this equation [mean Cu-Br bond length r = 2.377 A; calculated v(Cu-Br) 189 cm-', observed value 195 cm-'1.Applying the same calculation to the [Cu(dpa)X,] - species, we obtain ~(CU-X) 216 and 165 cm-' for X = C1 and Br respectively. On this basis the observed bands at 214 and 160 cm-' can be assigned to the B, ~(CU-X) modes for the X = C1 and Br respectively. The A l modes should occur at lower frequency, but this region of the spectrum is partly obscured by strong ligand bands which occur in the region 90-120 cm-'. In order to estimate the frequencies of the A , modes the metal-halogen stretching frequencies were calculated by carrying out a normal- co-ordinate analysis on an isolated C,, CuX, unit with an X-Cu-X bond angle of 11 5".A simple diagonal force field was used. This involves a Cu-X bond stretching force constant S, and an X-Cu-X angle bending force constant&. Withf, set equal to 0.1 S,, S, was varied and the vibrational frequencies calculated to give the best fit of the calculated to the observed frequencies. The results are given in Table 7, together with those obtained previously in a similar calculation on the CuBr, unit in [Cu(PPh,)Br,] - . 9 For both [Cu(dpa)X,] - species, weak bands or shoulders occur at the wavenumbers predicted for the A modes. However, these are not well enough resolved to allow definite assignments for these modes. The force constantsf, in Table 6 show reasonable relationships to one another, and this provides further support for the assignments on which they are based. Thus, the value for the four-co-ordinate [Cu(dpa)Br,] - is smaller than that for the three-co-ordinate [Cu(PPh,)Br,] -, and the value for [Cu(dpa)Cl,]- is greater than that for [Cu(dpa)Br,]-. Both of these trends are in line with those observed previously for species with one terminal Cu-X bond. l o References 1 Part 57, S. bin Silong, L. M. Engelhardt, and A. H. White, Aust. J . Chem., in the press. 2 L. M. Engelhardt, R. I. Papasergio, and A. H. White, Aust. J. Chem., 1984,37,2207. 3 P. C. Healy, C. Pakawatchai, and A. H. White, J. Chem. Soc., Dalton Trans., 1985,2531. 4 P. C. Healy, L. M. Engelhardt, V. A. Patrick, and A. H. White, J. Chem. Soc., Dalton Trans., 1985,2541. 5 J. A. Ibers and W. C. Hamilton (eds.), 'International Tables for X- Ray Crystallography,' Kynoch Press, Birmingham, 1974, vol. 4. 6 J. M. Stewart and S. R. Hall (eds.), The XTAL System, Technical Report TR- 1364, Computer Science Center, University of Maryland, U.S.A., 1983. 7 J. C. Dyason, L. M. Engelhardt, P. C. Healy, C. Pakawatchai, and A. H. White, Innorg. Chem., 1985,24, 1951. 8 D. L. Kepert, 'Inorganic Stereochemistry,' Springer, Berlin, 1982, p. 34. 9 G. A. Bowmaker, L. M. Engelhardt, P. C. Healy, and A. H. White, J. Chem. Soc., Dalton Trans., 1988,2825. 10 G. A. Bowmaker, P. C. Healy, J. D. Kildea, and A. H. White, Spectrochim. Acta, Part A, 1988,44, 1219. Received 29th March 1988; Paper 8/01303I

ISSN:1477-9226    

DOI:10.1039/DT9890001639

出版商:RSC    

年代:1989

数据来源: RSC