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Complexes between copper(I) chloride and polydentate aromatic amines
Inorganica Chimica Acta 350 (2003) 209 /214 www.elsevier.com/locate/ica
Complexes between copper(I) chloride and polydentate aromatic amines Bjo¨rn Gustafsson a, Mikael Ha˚kansson b, Susan Jagner a,* a
Department of Inorganic Chemistry, Chalmers University of Technology, SE-41296 Go¨teborg, Sweden b Organic Chemistry, Department of Chemistry, Go¨teborg University, SE-41296 Go¨teborg, Sweden Received 20 June 2002; accepted 2 October 2002 Dedicated to Prof. Dr. Pierre Braunstein
Abstract Two compounds containing polydentate aromatic amines have been prepared and characterised by means of crystal structure determination. Compound 1, catena -m-chloro-m-1,4-phenylenediamine-(acetonitrile)copper(I), is an infinite polymeric chain in which copper(I) is bridged alternately by the amine and by chloride. Compound 2, bis[tris(4-aminophenyl)amine](acetonitrile)chlorocopper(I), is a discrete monomer, neutral monomeric complexes being unusual among aminochlorocopper(I) compounds. Moreover, 2 would seem to be the first metal complex containing tris(4-aminophenyl)amine as a ligand whose structure has been determined. copper(I) exhibits distorted tetrahedral coordination geometry in both complexes. Whereas 1 decomposes owing to loss of acetonitrile solvent immediately on exposure to the atmosphere, 2 is far more resistant to decomposition, the solvent molecule being protected by intramolecular and intermolecular pockets formed by the phenyl groups of the triphenylamine ligand. # 2003 Elsevier Science B.V. All rights reserved. Keywords: Copper(I); Chloride; 1,4-Phenylenediamine; Tris(4-aminophenyl)amine; Acetonitrile; Crystal packing
1. Introduction The properties and rich structural chemistry of haloaminecopper(I) complexes have been described in a comprehensive review [1]. Further investigations, since then, include the incorporation of ligands containing Nand both N- and P-donors into halocuprate (I) species [2]. There has been considerable focus, which has accelerated in recent years, on complexes between copper(I) and tripodal amines with pendant aromatic arms, often pyridine-based, as biomimetic models in connection with the uptake of dioxygen [3]. Thus, protective pockets with a free coordination site for attack by dioxygen have been designed, and such entities have, moreover, been shown to be useful templates for the stabilisation of unusual coordination geometries of the copper(II) cation [4].
* Corresponding author. Tel.: /46-31-772 2852; fax: /46-31-772 2846. E-mail address: [email protected] (S. Jagner).
Our interest in this field stemmed from investigation of complexes between copper(I) and hard donors such as oxygen and the reactivity of such complexes with respect to carbonylation [5]. Somewhat surprisingly, however, there appears to be a lack of structural information concerning complexes between copper(I) and simple aromatic diamines such as the phenylenediamines, or triphenylamine. We have therefore attempted to prepare complexes between copper(I) chloride and phenylenediamine, succeeding to isolate a complex with p-phenylenediamine. In order to further investigate preferential bonding with respect to different nitrogen sites, we prepared a ligand with three pendant aminophenyl donors, viz. tris(4-aminophenyl)amine and examined its reactivity towards copper(I) chloride. We here report the preparation and structural characterisation of the novel complexes, catena -m-chloro-m1,4-phenylenediamine-(acetonitrile)copper(I) (1) and bis[tris(4-aminophenyl)amine](acetonitrile)-chlorocopper(I) (2), depicted in Schemes 1 and 2, respectively.
0020-1693/03/$ - see front matter # 2003 Elsevier Science B.V. All rights reserved. doi:10.1016/S0020-1693(02)01548-7
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B. Gustafsson et al. / Inorganica Chimica Acta 350 (2003) 209 /214
Scheme 1.
Scheme 2.
2. Experimental
2.1. General All operations were carried out under argon using standard Schlenk techniques. Copper(I) chloride was purified according to literature methods [6]. 1,4Phenylenediamine (Aldrich 97%) and acetonitrile (Riedel-de Hae¨n, maximum 0.001% H2O) were used as purchased and tris(4-aminophenyl)amine was prepared as grey crystals from tris(4-nitrophenyl)amine and hydrazine monohydrate according to literature methods [7].
2.3. Preparation of [CuCl(CH3CN)(N(C6H4(NH2))3)2] (2) Copper(I) chloride (0.95 mmol, 0.094 g) was dissolved in acetonitrile (1 ml), and tris(4-aminophenyl)amine (0.28 mmol, 0.108 g), dissolved in acetonitrile (7 ml), was added slowly with a syringe. The resulting solution changed the colour from pale-yellow to dark-blue. Paleblue and dark-blue (depending on the angle of observation) prisms of [CuCl(CH3CN)(N(C6H4(NH2))3)2], in approximately 50% yield, were deposited after a few minutes. The crystals darken in colour, ultimately becoming black, on exposure to air, decomposition being complete after approximately 2 h. 2.4. X-ray crystallography
2.2. Preparation of [Cu2(mCl)2(CH3CN)2(C6H4(NH2)2)] (1) Copper(I) chloride (2.0 mmol, 0.20 g) was dissolved in acetonitrile (3 ml), and 1,4-phenylenediamine (2.1 mmol; 0.23 g), dissolved in acetonitrile (4 ml), was added slowly with a syringe. Colourless needle-shaped crystals of [Cu2(m-Cl)2(CH3CN)2(C6H4(NH2)2)]8, in approximately 20% yield, began to form immediately. The compound is unstable and decomposes after a couple of minutes of exposure to the atmosphere.
Crystal and experimental data are summarised in Table 1. Crystals of 1 and 2 were mounted under argon in a glass capillary at /155 8C [8] and transferred in liquid nitrogen to a Rigaku AFC6R diffractometer. Diffracted intensities were measured using graphite˚ ) radiation monochromated Mo Ka (l /0.71073 A from a RU200 rotating anode operated at 9 kW (50 kV, 180 mA). Stationary background counts were recorded on each side of a reflection, the ratio of peak counting time to background counting time being 2:1. Weak reflections (I B/10.0s(I)) were rescanned up to
B. Gustafsson et al. / Inorganica Chimica Acta 350 (2003) 209 /214 Table 1 Crystallographic data for [Cu2(m-Cl)2(CH3CN)2(m-C6H4(NH2)2)] (1) and [CuCl(CH3CN)(N(C6H4(NH2))3)] (2) Compound
1
2
Empirical formula Formula weight Crystal system Space group ˚) a (A ˚) b (A ˚) c (A a (8) b (8) g (8) ˚ 3) V (A Z Dcalc (g cm 3) m (Mo Ka) (cm 1) Temperature (8C) Absorption correction Transmission coefficient 2umax (8) Data/restraints/par. R1 (I /2s (I )) wR2 (all reflections) Maximum/minimum residual electron ˚ 3) density (e A
C5H7ClCuN2 194.1 triclinic ¯ /P1 6.7263(12) 8.2865(10) 6.4944(6) 102.546(9) 96.719(11) 77.907(11) 344.53(8) 2 1.87 34.6 /110(2) c -scan 0.85 /1.0 50 1200/0/110 0.026 0.066 0.32; /0.36
C38H39ClCuN9 1810.7 monoclinic Pc 5.560(3) 26.932(3) 11.938(4) 90 96.16(4) 90 1777.4(11) 2 1.35 7.3 /143(2) c -scan 0.91 /1.0 50 3488/2/444 0.036 0.111 0.48; /0.40
R1 a½½Fo ½ ½Fc ½½=a½Fo ½; wR2 fa[w(Fo2 Fc2 )]2 =a[w(Fo2 )2 ]g1=2 :/
/
three times and counts accumulated to improve counting statistics. The intensities of three reflections were monitored regularly after the measurement of 150 reflections and indicated crystal stability during the diffraction experiments. Cell constants were obtained by least-squares refinement from the setting angles of 25 and 20 reflections for 1 and 2, respectively (39.208B/ 2u B/46.788 for 1; 13.408B/2u B/17.408 for 2). Correction was made for Lorentz and polarization effects. Empirical corrections based on azimuthal scans for several reflections were made for the effects of absorption. For 1, data were recorded at /110 8C for 58B/2u B/ 508 from a colourless cubic crystal fragment of approximate dimensions 0.20 /0.20 /0.20 mm3. The v /2u scan mode was employed with an v scan rate of 168 min 1 and a scan width of (1.21/0.30 tan u )8. A total of 1200 unique data were thus measured for h , k , l within the index ranges 0 B/h B/7, /9B/k B/9 and / 7 B/l B/7. The structure was solved by direct methods (SIR 92, [9]) and refined using full-matrix least-squares calculations on F2 (SHELXL-97, [10]) operating in the WINGX programme package [11]. Anisotropic thermal displacement parameters were refined for the nonhydrogen atoms; the hydrogen atoms were located from a difference map and refined with isotropic thermal parameters. Refinement of 110 parameters based on all 1200 reflections yielded R1 /0.026 and wR2 /0.061 for I /2s(I) (979 reflections) and R1 /
211
0.042 and wR2 /0.066 for all reflections; maximum and minimum residual electron density: 0.33; /0.36 e ˚ 3. A For 2, data were recorded at /143 8C for 58B/2u B/ 508 from a blue prismatic crystal of approximate dimensions 0.30 /0.20 /0.15 mm3. The v /2u scan mode was employed with an v scan rate of 168 min 1 and a scan width of (0.76/0.30 tan u )8. A total of 3488 unique data were thus measured for h , k , l within the index ranges 0 B/h B/6, 0 B/k B/32 and /14B/l B/14. Although the intensity distribution from this particular crystal indicated a centrosymmetric space group, it soon became apparent that the crystal was a twin, the correct space group being Pc . Previous data sets from two different crystals had indicated acentricity, but a C centred rather than a primitive cell. Although it was possible to solve and refine the structure in space group Cm from these data sets, with copper(I), chloride and acetonitrile situated on a mirror plane, to reasonable R values ( :/0.05), unreasonably large thermal displacement parameters were obtained for the atoms of the peripheral aminophenyl rings. The model obtained from the third data set, i.e. a twin in space group Pc , lacked these anomalies and was therefore considered to be correct. Anisotropic thermal displacement parameters were refined for all the non-hydrogen atoms; the phenyl hydrogen atoms were included as a riding contribution on the appropriate carbon atom, and the amino hydrogen atoms were located from a difference map and refined with fixed isotropic thermal parameters. Refinement of 444 parameters based on all 3488 reflections yielded R1 /0.036 and wR2 /0.086 for I /2s(I) (1928 reflections) and R1 /0.116 and wR2 /0.111 for all reflections; maximum and minimum residual electron ˚ 3. The final twin factor was density: 0.48; /0.40 e A 0.55(3). The structure was solved by direct methods (SIR 92, [9]) and refined using full-matrix least-squares calculations on F2 (SHELXL-97, [10]) operating in the WINGX programme package [11]. Molecular illustrations (Figs. 1 and 2) have been drawn with ORTEP-3 for Windows [12]. Selected interatomic distances and angles are given in Tables 2 and 3.
Fig. 1. The [Cu2(m-Cl)2(CH3CN)2(m-C6H4(NH2)2)] in 1, showing the crystallographic numbering. The starred atoms are related by centres of symmetry (for symmetry codes, see Table 2). Thermal ellipsoids enclose 50% probability.
B. Gustafsson et al. / Inorganica Chimica Acta 350 (2003) 209 /214
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Table 3 ˚ ) and angles (8) for [CuCl(CH3CN)Selected bond distances (A (N(C6H4(NH2))3)2] (2)
Fig. 2. The [CuCl(CH3CN)(N(C6H4(NH2))3)2] molecule in 2, showing the crystallographic numbering. Thermal ellipsoids enclose 50% probability. Table 2 ˚ ) and angles (8) for [Cu2(m-Cl)2(CH3CN)2(mSelected bond distances (A C6H4(NH2))2] (1) Bond distances Cu/N(1) Cu/Cl N/C(1) C(1)/C(2) C(2)/C(3 b)
2.119(3) 2.429(1) 1.444(4) 1.386(4) 1.392(4)
Cu/N(2) Cu/Cl a N(2)/C(4) C(4)/C(5) Cu/Cu a
1.985(3) 2.347(1) 1.134(4) 1.461(5) 3.042(1)
Bond angles N(1)/Cu/N(2) N(1)/Cu/Cl N(2)/Cu/Cl N(1)/Cu/Cl a N(2)/Cu/Cl a Cl /Cu /Cl a Cu/Cl /Cu a Cu/N(2)/C(4)
103.60(11) 102.70(9) 114.59(9) 120.25(9) 114.62(9) 100.90(3) 79.10(3) 161.0(3)
Cu/N(1)/C(1) N(1)/C(1) /C(2) N(1)/C(1) /C(3) C(2)/C(1)/C(3) C(1)/C(2)/C(3 a) C(1)/C(3)/C(2 a) N(2)/C(4) /C(5)
108.7(2) 119.7(3) 120.9(3) 119.2(3) 120.2(3) 120.5(3) 179.3(4)
a b
Symmetry code: /x , 2 /y , 2 /z . Symmetry code: 1 /x , 1 /y , 1 /z .
3. Results and discussion [Cu2(m-Cl)2(CH3CN)2(m-C6H4(NH2)2)] (1) is an infinite polymeric chain bridged alternately by chloride and 1,4-phenylenediamine (Scheme 1 and Fig. 1). Previously 1,4-phenylenediamine has been used as a spacer in porous copper(I) polymers [13]. In 1, the copper(I) centres are also bridged by chloride, and the central copper(I) /chloride core is a planar rectangle of the type often found in halocopper(I) complexes containing nitrogen donors [1,2] and in halocuprates(I) [14]. Copper(I) is further coordinated by an acetonitrile ˚ , the coordination geosolvent molecule at 1.985(3) A metry of the copper(I) centre thus being distorted tetrahedral. The Cu /N(amine) and Cu /Cl distances (Table 2) are unremarkable, and, as expected, the Cu / N(amine) distances are longer than Cu /N(NCCH3), owing to delocalisation of the lone-pair on the amine donor over the phenyl ring, causing the amine nitrogen
Bond distances Cu /N(1) Cu /Cl N(1)/C(1) N(2)/C(4) N(2)/C(7) N(2)/C(13) N(3)/C(10) N(4)/C(16) N(9)/C(37)
2.129(6) 2.341(2) 1.433(9) 1.426(10) 1.429(10) 1.435(10) 1.409(11) 1.392(10) 1.127(8)
Cu/N(5) Cu/N(9) N(5)/C(19) N(6)/C(22) N(6)/C(25) N(6)/C(31) N(7)/C(28) N(8)/C(34) C(37)/C(38)
2.166(6) 1.974(5) 1.426(9) 1.432(10) 1.438(11) 1.430(9) 1.420(10) 1.412(9) 1.470(9)
Bond angles N(1)/Cu/Cl N(1)/Cu/N(5) N(1)/Cu/N(9) N(5)/Cu/Cl N(5)/Cu/N(9) N(9)/Cu/Cl C(22)/N(6)/C(25) C(22)/N(6)/C(31)
105.7(2) 110.0(2) 103.2(2) 104.9(2) 101.1(2) 131.1(2) 119.4(6) 118.6(7)
Cu(1)/N(1)/C(1) Cu(1)/N(5)/C(19) Cu(1)/N(9)/C(37) N(9)/C(37)/C(38) C(4)/N(2)/C(7) C(4)/N(2)/C(13) C(7)/N(2)/C(13) C(25)/N(6)/C(31)
115.1(5) 117.0(5) 163.8(6) 179.3(10) 119.7(6) 118.8(6) 117.6(7) 119.4(7)
to act as a poorer donor. Loss of acetonitrile is, however, undoubtedly responsible for the instability of ˚ is the compound. The Cu /Cu separation at 3.042(1) A not indicative of any appreciable attractive interaction between the copper(I) centres. In contrast to 1, the complex between tris(4-aminophenyl)amine and copper(I) chloride, 2, is a discrete monomer (Scheme 2 and Fig. 2), but also with a coordinated solvent molecule. Few monomeric neutral chlorocopper(I) complexes with nitrogen donor ligands have, as yet been reported [1,15/17] and to the best of our knowledge 2 is the first example of a structurally determined metal complex containing tris(4-aminophenyl)amine as a ligand. Complex 2 shows a similar trend in Cu /N distances as 1, with a Cu /N(NCCH3) distance ˚ , and Cu /N(amine) distances of 2.129(6) of 1.974(5) A ˚ , respectively. The copper(I) centre and 2.166(6) A exhibits distorted tetrahedral coordination with a Cu / ˚ ) consistent with tetrahedral Cl bond length (2.341(2) A copper(I) coordination, if slightly long for a terminal bond. As is seen from Figs. 2 and 3, there is an almost perfect mirror plane through copper(I), chloride and acetonitrile. Close inspection of the molecule shows that the peripheral aminophenyl groups are not completely superimposed, as would be the case, were the mirror plane an exact feature of molecule 2. This is the origin of the large thermal displacement parameters associated with the model in space group Cm . The central nitrogen atoms of the tris(4-aminophenyl)amine ligands have compressed tetrahedral geometry ˚ from the with nitrogen situated approximately 0.15 A plane through the carbon atoms to which it is bonded, ˚ from the plane through i.e. N(2) is displaced 0.16(1) A ˚ C(4), C(7) and C(13), and N(6) is displaced 0.14(1) A from that through C(22), C(25) and C(31). The phenyl
B. Gustafsson et al. / Inorganica Chimica Acta 350 (2003) 209 /214
213
Fig. 3. View [18] of 2 perpendicular to the approximate mirror plane in [CuCl(CH3CN)(N(C6H4(NH2))3)2], showing the incomplete superimposition of the peripheral phenyl rings and the short Cl /H /N interactions which link the molecules to form layers. The ‘‘intermolecular pocket’’ which serves to trap the acetonitrile molecules is also evident.
rings exhibit typical propeller-like orientation with dihedral angles of 67.4(2)8, 78.8(3)8 and 79.3(3)8 between the rings attached to N(2) and 70.9(3)8, 78.7(3)8 and 76.6(3)8 between those attached to N(6). In both compounds, there are intramolecular Cl /H interactions within the lattice. Thus, in 1, the infinite chains are connected by Cl /H/N interactions of ˚ to form layers, which are in turn magnitude 2.65 A ˚ to neighconnected by Cl /H /N interactions 2.58 A bouring layers thus forming a 3D network. In compound 2, there are short Cl /H /N distances of 2.47 and ˚ which connect the molecules to form layers (cf. 2.62 A Fig. 3). As might be expected, contacts between copper(I) and the amino hydrogen atoms on the nitrogen donors are short in both compounds (of the ˚ ). This is probably due to steric crowding order of 2.6 A at the copper(I) centre rather than to the influence of attractive Cu /H interactions per se. The compounds differ radically in their ability to lose acetonitrile. It is possible that the reduced tendency of compound 2 to lose solvent can be attributed in part to a partially protecting intramolecular pocket formed by the tris(4-aminophenyl)amine ligands (see Fig. 4). In addition, as is seen from Fig. 3, the solvent is wedged between phenyl groups belonging to adjacent molecules, which can be considered to provide a protecting intermolecular pocket. Owing to these two features, acetonitrile appears, from a complete space-filling model, to be totally encapsulated within the lattice, which could provide a rationale for the comparative stability of the compound with respect to loss of solvent.
Fig. 4. Space-filling model [18] of the [CuCl(CH3CN)(N(C6H4(NH2))3)2] molecule illustrating the protrusion of acetonitrile from the ‘‘intramolecular pocket’’ formed by the tris(4-aminophenyl)amine ligands.
Cambridge Crystallographic Data Centre, CCDC Nos. 187410 for 1 and 187411 for 2. Copies of this information may be obtained free of charge from The Director, CCDC, 12 Union Road, Cambridge CB2 1EZ, UK (fax: /44-1223-336-033; e-mail: [email protected]).
Acknowledgements Financial support from the Swedish Research Council (Natural and Engineering Sciences VR/NFR)) is gratefully acknowledged.
4. Supplementary material References Crystallographic data (excluding structure factors) for the structural analysis have been deposited with the
[1] K.G. Caulton, G. Davies, E.M. Holt, Polyhedron 9 (1990) 2319.
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[2] See, for example, (a) G.A. Bowmaker, P.C. Healy, D.L. Kepert, J.D. Kildea, B.W. Skelton, A.H. White, J. Chem. Soc., Dalton Trans. (1989) 1639; (b) G.A. Bowmaker, J.V. Hanna, R.D. Hart, P.C. Healy, A.H. White, J. Chem. Soc., Dalton Trans. (1994) 2621; (c) P.M. Graham, R.D. Pike, M. Sabat, R.D. Bailey, W.T. Pennington, Inorg. Chem. 39 (2000) 5121. [3] See, for example, (a) M. Schatz, M. Becker, F. Thaler, F. Hampel, S. Schindler, R.R. Jacobson, Z. Tyekla´r, N.N. Murthy, P. Ghosh, Q. Chen, J. Zubieta, K.D. Karlin, Inorg. Chem. 40 (2001) 2312; (b) C.-L. Chuang, K. Lim, Q. Chen, J. Zubieta, J.W. Canary, Inorg. Chem. 34 (1995) 2562; (c) M. Becker, F.W. Heinemann, S. Schindler, Chem. Eur. J. 5 (1999) 3124; (d) M. Schatz, M. Becker, O. Walther, G. Liehr, S. Schindler, Inorg. Chim. Acta 324 (2001) 173. [4] (a) P.L. Holland, W.B. Tolman, J. Am. Chem. Soc. 121 (1999) 7270; (b) D.W. Randall, S.D. George, P.L. Holland, B. Hedman, K.O. Hodgson, W.B. Tolman, E.I. Solomon, J. Am. Chem. Soc. 122 (2000) 11632. [5] (a) C. Lopes, M. Ha˚kansson, S. Jagner, Inorg. Chem. 36 (1997) 3232; (b) M. Ha˚kansson, C. Lopes, S. Jagner, Inorg. Chim. Acta 304 (2000) 178; (c) M. Ha˚kansson, C. Lopes, S. Jagner, Organometallics 17 (1998)
[6] [7] [8] [9] [10]
[11] [12] [13] [14] [15] [16] [17] [18]
210; (d) C. Lopes, M. Ha˚kansson, S. Jagner, New J. Chem. 21 (1997) 1113; (e) B. Gustafsson, M. Ha˚kansson, G. Westman, S. Jagner, J. Organomet. Chem. 649 (2002) 204. R.N. Keller, H.D. Wycoff, Inorg. Synth. 2 (1946) 1. J. Fang, H. Kita, K. Okamoto, Macromolecules 33 (2000) 4639. M. Ha˚kansson, Inorg. Synth. 32 (1998) 222. A. Altomare, G. Cascarano, C. Giacovazzo, A. Guagliardi, J. Appl. Crystallogr. 26 (1993) 343 (SIR 92). G.M. Sheldrick, SHELX97 (Release 97-2), Institu¨t fu¨r Anorganische Chemie der Universita¨t Go¨ttingen, Go¨ttingen, Germany, 1998. L.J. Farrugia, J. Appl. Crystallogr. 32 (1999) 837. L.J. Farrugia, J. Appl. Crystallogr. 30 (1997) 565. I.M. Mu¨ller, T. Ro¨ttgers, W.S. Sheldrick, Chem. Commun. (1998) 823. S. Jagner, G. Helgesson, Adv. Inorg. Chem. 37 (1991) 1. E.W. Ainscough, A.G. Bingham, A.M. Brodie, K.L. Brown, J. Chem. Soc., Dalton Trans. (1984) 989. J.C. Dyason, P.C. Healy, C. Pakawatchai, V.A. Patrick, A.H. White, Inorg. Chem. 24 (1985) 1957. J.C. Dyason, L.M. Engelhardt, P.C. Healy, A.H. White, Aust. J. Chem. 39 (1986) 1043. K. Brandenburg, Diamond 2.1c ed., Crystal Impact GbR, 1996 / 1999.
Complexes between copper(I) chloride and polydentate aromatic amines Bjo¨rn Gustafsson a, Mikael Ha˚kansson b, Susan Jagner a,* a
Department of Inorganic Chemistry, Chalmers University of Technology, SE-41296 Go¨teborg, Sweden b Organic Chemistry, Department of Chemistry, Go¨teborg University, SE-41296 Go¨teborg, Sweden Received 20 June 2002; accepted 2 October 2002 Dedicated to Prof. Dr. Pierre Braunstein
Abstract Two compounds containing polydentate aromatic amines have been prepared and characterised by means of crystal structure determination. Compound 1, catena -m-chloro-m-1,4-phenylenediamine-(acetonitrile)copper(I), is an infinite polymeric chain in which copper(I) is bridged alternately by the amine and by chloride. Compound 2, bis[tris(4-aminophenyl)amine](acetonitrile)chlorocopper(I), is a discrete monomer, neutral monomeric complexes being unusual among aminochlorocopper(I) compounds. Moreover, 2 would seem to be the first metal complex containing tris(4-aminophenyl)amine as a ligand whose structure has been determined. copper(I) exhibits distorted tetrahedral coordination geometry in both complexes. Whereas 1 decomposes owing to loss of acetonitrile solvent immediately on exposure to the atmosphere, 2 is far more resistant to decomposition, the solvent molecule being protected by intramolecular and intermolecular pockets formed by the phenyl groups of the triphenylamine ligand. # 2003 Elsevier Science B.V. All rights reserved. Keywords: Copper(I); Chloride; 1,4-Phenylenediamine; Tris(4-aminophenyl)amine; Acetonitrile; Crystal packing
1. Introduction The properties and rich structural chemistry of haloaminecopper(I) complexes have been described in a comprehensive review [1]. Further investigations, since then, include the incorporation of ligands containing Nand both N- and P-donors into halocuprate (I) species [2]. There has been considerable focus, which has accelerated in recent years, on complexes between copper(I) and tripodal amines with pendant aromatic arms, often pyridine-based, as biomimetic models in connection with the uptake of dioxygen [3]. Thus, protective pockets with a free coordination site for attack by dioxygen have been designed, and such entities have, moreover, been shown to be useful templates for the stabilisation of unusual coordination geometries of the copper(II) cation [4].
* Corresponding author. Tel.: /46-31-772 2852; fax: /46-31-772 2846. E-mail address: [email protected] (S. Jagner).
Our interest in this field stemmed from investigation of complexes between copper(I) and hard donors such as oxygen and the reactivity of such complexes with respect to carbonylation [5]. Somewhat surprisingly, however, there appears to be a lack of structural information concerning complexes between copper(I) and simple aromatic diamines such as the phenylenediamines, or triphenylamine. We have therefore attempted to prepare complexes between copper(I) chloride and phenylenediamine, succeeding to isolate a complex with p-phenylenediamine. In order to further investigate preferential bonding with respect to different nitrogen sites, we prepared a ligand with three pendant aminophenyl donors, viz. tris(4-aminophenyl)amine and examined its reactivity towards copper(I) chloride. We here report the preparation and structural characterisation of the novel complexes, catena -m-chloro-m1,4-phenylenediamine-(acetonitrile)copper(I) (1) and bis[tris(4-aminophenyl)amine](acetonitrile)-chlorocopper(I) (2), depicted in Schemes 1 and 2, respectively.
0020-1693/03/$ - see front matter # 2003 Elsevier Science B.V. All rights reserved. doi:10.1016/S0020-1693(02)01548-7
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B. Gustafsson et al. / Inorganica Chimica Acta 350 (2003) 209 /214
Scheme 1.
Scheme 2.
2. Experimental
2.1. General All operations were carried out under argon using standard Schlenk techniques. Copper(I) chloride was purified according to literature methods [6]. 1,4Phenylenediamine (Aldrich 97%) and acetonitrile (Riedel-de Hae¨n, maximum 0.001% H2O) were used as purchased and tris(4-aminophenyl)amine was prepared as grey crystals from tris(4-nitrophenyl)amine and hydrazine monohydrate according to literature methods [7].
2.3. Preparation of [CuCl(CH3CN)(N(C6H4(NH2))3)2] (2) Copper(I) chloride (0.95 mmol, 0.094 g) was dissolved in acetonitrile (1 ml), and tris(4-aminophenyl)amine (0.28 mmol, 0.108 g), dissolved in acetonitrile (7 ml), was added slowly with a syringe. The resulting solution changed the colour from pale-yellow to dark-blue. Paleblue and dark-blue (depending on the angle of observation) prisms of [CuCl(CH3CN)(N(C6H4(NH2))3)2], in approximately 50% yield, were deposited after a few minutes. The crystals darken in colour, ultimately becoming black, on exposure to air, decomposition being complete after approximately 2 h. 2.4. X-ray crystallography
2.2. Preparation of [Cu2(mCl)2(CH3CN)2(C6H4(NH2)2)] (1) Copper(I) chloride (2.0 mmol, 0.20 g) was dissolved in acetonitrile (3 ml), and 1,4-phenylenediamine (2.1 mmol; 0.23 g), dissolved in acetonitrile (4 ml), was added slowly with a syringe. Colourless needle-shaped crystals of [Cu2(m-Cl)2(CH3CN)2(C6H4(NH2)2)]8, in approximately 20% yield, began to form immediately. The compound is unstable and decomposes after a couple of minutes of exposure to the atmosphere.
Crystal and experimental data are summarised in Table 1. Crystals of 1 and 2 were mounted under argon in a glass capillary at /155 8C [8] and transferred in liquid nitrogen to a Rigaku AFC6R diffractometer. Diffracted intensities were measured using graphite˚ ) radiation monochromated Mo Ka (l /0.71073 A from a RU200 rotating anode operated at 9 kW (50 kV, 180 mA). Stationary background counts were recorded on each side of a reflection, the ratio of peak counting time to background counting time being 2:1. Weak reflections (I B/10.0s(I)) were rescanned up to
B. Gustafsson et al. / Inorganica Chimica Acta 350 (2003) 209 /214 Table 1 Crystallographic data for [Cu2(m-Cl)2(CH3CN)2(m-C6H4(NH2)2)] (1) and [CuCl(CH3CN)(N(C6H4(NH2))3)] (2) Compound
1
2
Empirical formula Formula weight Crystal system Space group ˚) a (A ˚) b (A ˚) c (A a (8) b (8) g (8) ˚ 3) V (A Z Dcalc (g cm 3) m (Mo Ka) (cm 1) Temperature (8C) Absorption correction Transmission coefficient 2umax (8) Data/restraints/par. R1 (I /2s (I )) wR2 (all reflections) Maximum/minimum residual electron ˚ 3) density (e A
C5H7ClCuN2 194.1 triclinic ¯ /P1 6.7263(12) 8.2865(10) 6.4944(6) 102.546(9) 96.719(11) 77.907(11) 344.53(8) 2 1.87 34.6 /110(2) c -scan 0.85 /1.0 50 1200/0/110 0.026 0.066 0.32; /0.36
C38H39ClCuN9 1810.7 monoclinic Pc 5.560(3) 26.932(3) 11.938(4) 90 96.16(4) 90 1777.4(11) 2 1.35 7.3 /143(2) c -scan 0.91 /1.0 50 3488/2/444 0.036 0.111 0.48; /0.40
R1 a½½Fo ½ ½Fc ½½=a½Fo ½; wR2 fa[w(Fo2 Fc2 )]2 =a[w(Fo2 )2 ]g1=2 :/
/
three times and counts accumulated to improve counting statistics. The intensities of three reflections were monitored regularly after the measurement of 150 reflections and indicated crystal stability during the diffraction experiments. Cell constants were obtained by least-squares refinement from the setting angles of 25 and 20 reflections for 1 and 2, respectively (39.208B/ 2u B/46.788 for 1; 13.408B/2u B/17.408 for 2). Correction was made for Lorentz and polarization effects. Empirical corrections based on azimuthal scans for several reflections were made for the effects of absorption. For 1, data were recorded at /110 8C for 58B/2u B/ 508 from a colourless cubic crystal fragment of approximate dimensions 0.20 /0.20 /0.20 mm3. The v /2u scan mode was employed with an v scan rate of 168 min 1 and a scan width of (1.21/0.30 tan u )8. A total of 1200 unique data were thus measured for h , k , l within the index ranges 0 B/h B/7, /9B/k B/9 and / 7 B/l B/7. The structure was solved by direct methods (SIR 92, [9]) and refined using full-matrix least-squares calculations on F2 (SHELXL-97, [10]) operating in the WINGX programme package [11]. Anisotropic thermal displacement parameters were refined for the nonhydrogen atoms; the hydrogen atoms were located from a difference map and refined with isotropic thermal parameters. Refinement of 110 parameters based on all 1200 reflections yielded R1 /0.026 and wR2 /0.061 for I /2s(I) (979 reflections) and R1 /
211
0.042 and wR2 /0.066 for all reflections; maximum and minimum residual electron density: 0.33; /0.36 e ˚ 3. A For 2, data were recorded at /143 8C for 58B/2u B/ 508 from a blue prismatic crystal of approximate dimensions 0.30 /0.20 /0.15 mm3. The v /2u scan mode was employed with an v scan rate of 168 min 1 and a scan width of (0.76/0.30 tan u )8. A total of 3488 unique data were thus measured for h , k , l within the index ranges 0 B/h B/6, 0 B/k B/32 and /14B/l B/14. Although the intensity distribution from this particular crystal indicated a centrosymmetric space group, it soon became apparent that the crystal was a twin, the correct space group being Pc . Previous data sets from two different crystals had indicated acentricity, but a C centred rather than a primitive cell. Although it was possible to solve and refine the structure in space group Cm from these data sets, with copper(I), chloride and acetonitrile situated on a mirror plane, to reasonable R values ( :/0.05), unreasonably large thermal displacement parameters were obtained for the atoms of the peripheral aminophenyl rings. The model obtained from the third data set, i.e. a twin in space group Pc , lacked these anomalies and was therefore considered to be correct. Anisotropic thermal displacement parameters were refined for all the non-hydrogen atoms; the phenyl hydrogen atoms were included as a riding contribution on the appropriate carbon atom, and the amino hydrogen atoms were located from a difference map and refined with fixed isotropic thermal parameters. Refinement of 444 parameters based on all 3488 reflections yielded R1 /0.036 and wR2 /0.086 for I /2s(I) (1928 reflections) and R1 /0.116 and wR2 /0.111 for all reflections; maximum and minimum residual electron ˚ 3. The final twin factor was density: 0.48; /0.40 e A 0.55(3). The structure was solved by direct methods (SIR 92, [9]) and refined using full-matrix least-squares calculations on F2 (SHELXL-97, [10]) operating in the WINGX programme package [11]. Molecular illustrations (Figs. 1 and 2) have been drawn with ORTEP-3 for Windows [12]. Selected interatomic distances and angles are given in Tables 2 and 3.
Fig. 1. The [Cu2(m-Cl)2(CH3CN)2(m-C6H4(NH2)2)] in 1, showing the crystallographic numbering. The starred atoms are related by centres of symmetry (for symmetry codes, see Table 2). Thermal ellipsoids enclose 50% probability.
B. Gustafsson et al. / Inorganica Chimica Acta 350 (2003) 209 /214
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Table 3 ˚ ) and angles (8) for [CuCl(CH3CN)Selected bond distances (A (N(C6H4(NH2))3)2] (2)
Fig. 2. The [CuCl(CH3CN)(N(C6H4(NH2))3)2] molecule in 2, showing the crystallographic numbering. Thermal ellipsoids enclose 50% probability. Table 2 ˚ ) and angles (8) for [Cu2(m-Cl)2(CH3CN)2(mSelected bond distances (A C6H4(NH2))2] (1) Bond distances Cu/N(1) Cu/Cl N/C(1) C(1)/C(2) C(2)/C(3 b)
2.119(3) 2.429(1) 1.444(4) 1.386(4) 1.392(4)
Cu/N(2) Cu/Cl a N(2)/C(4) C(4)/C(5) Cu/Cu a
1.985(3) 2.347(1) 1.134(4) 1.461(5) 3.042(1)
Bond angles N(1)/Cu/N(2) N(1)/Cu/Cl N(2)/Cu/Cl N(1)/Cu/Cl a N(2)/Cu/Cl a Cl /Cu /Cl a Cu/Cl /Cu a Cu/N(2)/C(4)
103.60(11) 102.70(9) 114.59(9) 120.25(9) 114.62(9) 100.90(3) 79.10(3) 161.0(3)
Cu/N(1)/C(1) N(1)/C(1) /C(2) N(1)/C(1) /C(3) C(2)/C(1)/C(3) C(1)/C(2)/C(3 a) C(1)/C(3)/C(2 a) N(2)/C(4) /C(5)
108.7(2) 119.7(3) 120.9(3) 119.2(3) 120.2(3) 120.5(3) 179.3(4)
a b
Symmetry code: /x , 2 /y , 2 /z . Symmetry code: 1 /x , 1 /y , 1 /z .
3. Results and discussion [Cu2(m-Cl)2(CH3CN)2(m-C6H4(NH2)2)] (1) is an infinite polymeric chain bridged alternately by chloride and 1,4-phenylenediamine (Scheme 1 and Fig. 1). Previously 1,4-phenylenediamine has been used as a spacer in porous copper(I) polymers [13]. In 1, the copper(I) centres are also bridged by chloride, and the central copper(I) /chloride core is a planar rectangle of the type often found in halocopper(I) complexes containing nitrogen donors [1,2] and in halocuprates(I) [14]. Copper(I) is further coordinated by an acetonitrile ˚ , the coordination geosolvent molecule at 1.985(3) A metry of the copper(I) centre thus being distorted tetrahedral. The Cu /N(amine) and Cu /Cl distances (Table 2) are unremarkable, and, as expected, the Cu / N(amine) distances are longer than Cu /N(NCCH3), owing to delocalisation of the lone-pair on the amine donor over the phenyl ring, causing the amine nitrogen
Bond distances Cu /N(1) Cu /Cl N(1)/C(1) N(2)/C(4) N(2)/C(7) N(2)/C(13) N(3)/C(10) N(4)/C(16) N(9)/C(37)
2.129(6) 2.341(2) 1.433(9) 1.426(10) 1.429(10) 1.435(10) 1.409(11) 1.392(10) 1.127(8)
Cu/N(5) Cu/N(9) N(5)/C(19) N(6)/C(22) N(6)/C(25) N(6)/C(31) N(7)/C(28) N(8)/C(34) C(37)/C(38)
2.166(6) 1.974(5) 1.426(9) 1.432(10) 1.438(11) 1.430(9) 1.420(10) 1.412(9) 1.470(9)
Bond angles N(1)/Cu/Cl N(1)/Cu/N(5) N(1)/Cu/N(9) N(5)/Cu/Cl N(5)/Cu/N(9) N(9)/Cu/Cl C(22)/N(6)/C(25) C(22)/N(6)/C(31)
105.7(2) 110.0(2) 103.2(2) 104.9(2) 101.1(2) 131.1(2) 119.4(6) 118.6(7)
Cu(1)/N(1)/C(1) Cu(1)/N(5)/C(19) Cu(1)/N(9)/C(37) N(9)/C(37)/C(38) C(4)/N(2)/C(7) C(4)/N(2)/C(13) C(7)/N(2)/C(13) C(25)/N(6)/C(31)
115.1(5) 117.0(5) 163.8(6) 179.3(10) 119.7(6) 118.8(6) 117.6(7) 119.4(7)
to act as a poorer donor. Loss of acetonitrile is, however, undoubtedly responsible for the instability of ˚ is the compound. The Cu /Cu separation at 3.042(1) A not indicative of any appreciable attractive interaction between the copper(I) centres. In contrast to 1, the complex between tris(4-aminophenyl)amine and copper(I) chloride, 2, is a discrete monomer (Scheme 2 and Fig. 2), but also with a coordinated solvent molecule. Few monomeric neutral chlorocopper(I) complexes with nitrogen donor ligands have, as yet been reported [1,15/17] and to the best of our knowledge 2 is the first example of a structurally determined metal complex containing tris(4-aminophenyl)amine as a ligand. Complex 2 shows a similar trend in Cu /N distances as 1, with a Cu /N(NCCH3) distance ˚ , and Cu /N(amine) distances of 2.129(6) of 1.974(5) A ˚ , respectively. The copper(I) centre and 2.166(6) A exhibits distorted tetrahedral coordination with a Cu / ˚ ) consistent with tetrahedral Cl bond length (2.341(2) A copper(I) coordination, if slightly long for a terminal bond. As is seen from Figs. 2 and 3, there is an almost perfect mirror plane through copper(I), chloride and acetonitrile. Close inspection of the molecule shows that the peripheral aminophenyl groups are not completely superimposed, as would be the case, were the mirror plane an exact feature of molecule 2. This is the origin of the large thermal displacement parameters associated with the model in space group Cm . The central nitrogen atoms of the tris(4-aminophenyl)amine ligands have compressed tetrahedral geometry ˚ from the with nitrogen situated approximately 0.15 A plane through the carbon atoms to which it is bonded, ˚ from the plane through i.e. N(2) is displaced 0.16(1) A ˚ C(4), C(7) and C(13), and N(6) is displaced 0.14(1) A from that through C(22), C(25) and C(31). The phenyl
B. Gustafsson et al. / Inorganica Chimica Acta 350 (2003) 209 /214
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Fig. 3. View [18] of 2 perpendicular to the approximate mirror plane in [CuCl(CH3CN)(N(C6H4(NH2))3)2], showing the incomplete superimposition of the peripheral phenyl rings and the short Cl /H /N interactions which link the molecules to form layers. The ‘‘intermolecular pocket’’ which serves to trap the acetonitrile molecules is also evident.
rings exhibit typical propeller-like orientation with dihedral angles of 67.4(2)8, 78.8(3)8 and 79.3(3)8 between the rings attached to N(2) and 70.9(3)8, 78.7(3)8 and 76.6(3)8 between those attached to N(6). In both compounds, there are intramolecular Cl /H interactions within the lattice. Thus, in 1, the infinite chains are connected by Cl /H/N interactions of ˚ to form layers, which are in turn magnitude 2.65 A ˚ to neighconnected by Cl /H /N interactions 2.58 A bouring layers thus forming a 3D network. In compound 2, there are short Cl /H /N distances of 2.47 and ˚ which connect the molecules to form layers (cf. 2.62 A Fig. 3). As might be expected, contacts between copper(I) and the amino hydrogen atoms on the nitrogen donors are short in both compounds (of the ˚ ). This is probably due to steric crowding order of 2.6 A at the copper(I) centre rather than to the influence of attractive Cu /H interactions per se. The compounds differ radically in their ability to lose acetonitrile. It is possible that the reduced tendency of compound 2 to lose solvent can be attributed in part to a partially protecting intramolecular pocket formed by the tris(4-aminophenyl)amine ligands (see Fig. 4). In addition, as is seen from Fig. 3, the solvent is wedged between phenyl groups belonging to adjacent molecules, which can be considered to provide a protecting intermolecular pocket. Owing to these two features, acetonitrile appears, from a complete space-filling model, to be totally encapsulated within the lattice, which could provide a rationale for the comparative stability of the compound with respect to loss of solvent.
Fig. 4. Space-filling model [18] of the [CuCl(CH3CN)(N(C6H4(NH2))3)2] molecule illustrating the protrusion of acetonitrile from the ‘‘intramolecular pocket’’ formed by the tris(4-aminophenyl)amine ligands.
Cambridge Crystallographic Data Centre, CCDC Nos. 187410 for 1 and 187411 for 2. Copies of this information may be obtained free of charge from The Director, CCDC, 12 Union Road, Cambridge CB2 1EZ, UK (fax: /44-1223-336-033; e-mail: [email protected]).
Acknowledgements Financial support from the Swedish Research Council (Natural and Engineering Sciences VR/NFR)) is gratefully acknowledged.
4. Supplementary material References Crystallographic data (excluding structure factors) for the structural analysis have been deposited with the
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