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Some copper(I) and copper(II) complexes of two new potentially heptadentate tripodal Schiff base ligands
Polyhedron
Vol.
9, No.
20, pp.
2463-2467,
1990
0277-5387/90 S3.OOf.W 0 1990 Pergamon Press plc
Printed in Great Britain
SOME COPPER(I) AND COPPER@) COMPLEXES OF TWO NEW POTENTIALLY HEPTADENTATE TRIPODAL SCHIFF BASE LIGANDS ELMER C. ALYEA,* GEORGE FERGUSON
and MICHAEL
JENNINGS
Department of Chemistry and Biochemistry, University of Guelph, Guelph, Ontario N 1G 2W 1 Canada and BAOLONG
Coordination
LI, ZHENG
XU and XIAOZENG
YOU
Chemistry Institute, Nanjing University, Nanjing, P.R.C. and SIIIXIONG
LIU
Institute of Structural Chemistry, Fuzhou University, Fuzhou, P.R.C. (Received 27 September 1989; accepted 21 May 1990) Abstract-Two
potentially heptadentate tripodal Schiff base ligands, tris[4-(2-thienyl)-3aza-3-butenyllamine (S3tren) and tris[4-(2-furyl)-3-aza-3-butenyllamine (0,tren) have been prepared and characterized by ‘H and 13C NMR spectral data. For the complexes [Cu (E,tren)]BPh, (E = S, 0), NMR spectral shifts clearly indicate coordination of all four nitrogen donor atoms. X-ray analysis for [Cu(S,tren)]BPh, shows trigonal pyramidal geometry for the copper(I) cation, with all Co---S distances [average of 3.344(4) A] being too great for any bonding interaction. IR, ESR and electronic spectral data for the green copper(I1) complexes, CuX2 - S,tren (X = Cl, Br), indicate six-coordination in the solid state and square pyramidal geometry (with halide dissociation) in freshly prepared dimethylformamide solutions.
(1) PYstren
(2)
Although seven-coordination is readily achieved by many metal ions, ‘,2 the ability of a single ligand to supply all seven donor atoms is rare.3 The best studied potentially heptadentate ligand, tris[4-(2pyridyl)-3-aza-3-butenyllamine, known as py3tren (l), was designed to give transition metal complexes having mono-capped trigonal antiprismatic coordination polyhedra. 4*5 A recent detailed assessment of the bonding properties of py,tren in a
E = S, S3tren; (3) E = 0, O+en
series of [M(py3tren)]‘+ (M = Mn, Fe, Co, Ni, Cu and Zn) complexes shows, however, that the seventh bond to the apical or bridgehead nitrogen atom may only be considered as “weakly bonding” in the case of manganese [2.794(2) A] and cobalt [2.870(2) A]. ’ In order to overcome the domineering influence of the three pendant cl-diimine chelating arms on the resultant metal geometry, we have prepared two new analogous ligands that contain thiophene and furan moieties in the pendant arms. These potentially heptadentate tripodal Schiff base ligands, *Author to whom correspondence should be addressed. called S,tren (2) amd 0,tren (3) are expected to 2463
2464
E. C. ALYEA et al.
enhance metal interaction with the bridgehead nitrogen atom as compared to pyfren. 5The importance of multiden~~ nitrogen-s~ph~ ligands in copper model systems for the “blue” copper oxidases and electron transfer proteins6 led us to explore the coordinating ability of 2 and 3 with both copper(I) and copper(I1) ions, which we report in this paper. The syntheses of the new potentially heptadentate ligands 2 and 3 were readily effected by the Schiff base condensation of tris(2~aminoethyl)amine (tren) with the appropriate aldehyde. S,tren precipitated from the absolute ethanol solution as a white solid in 93% yield (m.p. 135-137°C) and gave satisfactory elemental analysis ; 0 $ren was isolated as an easily hydrolysed oil and thus was characterized by spectral methods. ‘H and i3C NMR spectral data (coupled and decoupled) acquired on a Bruker WH-400 spectrometer provided confirmatory evidence for the formation of the expected three azomethine linkages. The assignment of ‘H
and 13C resonances according to the above structural formula for 2 and 3 (Table 1) was based on those observed for the precursors. Characteristic mass spectral molecular ion and fR v(C=N) stretching frequencies occurred at 428 m/z,1637 ctn ’ (2) and at 380 m/z,1647 cm-’ (3). An X-ray crystallographic analysis of S,tren has confirmed the tripodal geometry of the ligand and revealed the conjugation of the thiophene moieties with the azomethine linkages7 The reactions of 2 with CuXZ salts gave [CuL]Y and CuX2 *L, where Y = I,, BPh4 and X = Cl, Br, N3, SCN, C104, NU3. The copper(I) complexes were obtained by the addition of excess NaY to solutions containing Cu(OAc)~ and L ; [~u(O~~en)] BPh4 was isolated in a similar fashion. Copper(I1) is well known to be easily converted to copper(I) by various mild reducing agents or ligands,‘” for example, the tripodal ligand tris(2-methylthioethyl)amine (N&-Me) forms [Cu(NS,-Me)]E, due to the instability of the initial copper(I1) com-
Tabie 1. ‘H and ’ ‘C NMR spectral data ‘I-I data” &(ppm) and J(Hz)
’ 3C data” ~~pprn~ and J(Hz)
S$renh
8.10 (H,), 7.36 (I-I,, d, Jcd = 5.2) 6.99 (H,, dd, Jti = 5.1, &, = 3.7), 6.69 (H,,, d, & = 3.7), 3.58 (H,, t, J,r = 5.7), 2.82 (I& t, J,r = 5.7)
155.29 (C,, d, J = 161.6), 142.73 (C,), 130.28 (C,, d, J = 176.7), 128.35 (C, d, J= 194.8), 127.28 (C,, d, J= 168.8), 59.58 (C,, t, J= 134.4), 55.67 (C,, t, J = 132.7)
0 #en”
7.91 (Ha), 6.45-6.42 (Hi,, H,, Hd, m). 3.63 (H,, t, & = 5.9), 2.88 (Hr. t, J,r = 6.1)
151.44 (C,,), 150.63 (C,, d, J = 161.6), 144.48 (C,, d, J = 202.6); 113.76 (&,d,J= 175.9); 111,51(C,,,d, J = 176.7): 59.71 (C,, t, J = 134.3), 55.35 (C, t, J = 133.1)
Compound
8.78 (Ha), 7.76 (H6, dd, Jbd = 3.7, J = 1.2), 7.63 (H,, d, Jcd = 5.2), 7?4 (H, phenyl, m), 7.18 (H,,, dd, Jcd = 5.2, Jbd = 3.7), 6.92 (H, phenyl, t, J = 7.4) 6.77 (H, phenyl, t, J = 7.3), 3.80 (II,, t, J = 5.3), 3.13 (Hf, t, J = 5.4) 8.33 (H,), 7.47 (Hi,, d, & = 1.4), 7.44 (H,, d, &, = 3.5), 7.34 (H, phenyl, t, J = 3.1), 6.92 (H, phenyl, t, J = ‘7.3), 6.77 (H, pbenyl, t, J = 7.2), 6.65 (Hd, dd, Jcd = 3.5, Jbd = 1.6), 3.81 (H,, dd, J = 5.9, J = 4.8), 3.16 (Hn dd, J = 6.3, J = 5.0) “d = doublet, dd = doublet of doublets, m = multiplet, t = triplet. ’ CDCl, solution. ‘Tentative assignment. ‘(CD,)&0 solution. e Insufficiency soluble.
Heptadentate tripodal Schiff base ligands with Cu’ and Cu”
2465
plex, [Cu(NS3-Me)I]C104.8b The isolation of [ML]
(OAc)(BPh,) complexes, where M = Mn, Fe, Co, Ni and L = 2 and 3, has also been accomplished and spectral and structural characterization is underway. ’ Preliminary ‘H NMR spectral data for [CuL]BPh,, where L = 2 and 3, and ESR and visible spectra data for CuX2 * S,tren, where X = Cl and Br, are presented here. Downfield shifts of proton resonances in the ‘H NMR spectra of [CuL]BPh, (L = 2 and 3), compared to those observed for the free ligands, clearly indicate coordination of all four nitrogen donor atoms. The shifts are the most dramatic for the azomethine protons [(H,) 0.68 (2) vs 0.42 (3) ppm] and ethylene protons [0.22, 0.31 (2) vs 0.18, 0.29 ppm (3) for H, and Hf, respectively]. Resonances due to ring protons are also shifted downfield in the complexes (Table I), but it is less clear whether this occurs due to E atom complexation. The large shift for H,, (1.07 and 1.03 ppm for 2 and 3, respectively) could occur simply as a result of increased conjugation with the C&N linkage ; the shift of only ca 0.2 ppm, which occurs for Hd in both complexes, supports this idea rather than coordination of the E atoms. However, the shift for H, is much larger for 3 (1 .Ol vs 0.27 ppm for 2), implying that the Cu-0 interaction is significantly greater than the Cu-S interaction. X-ray investigations are underway to resolve this ambi~ity ; results for [CuL]BPh, (L = 2) confirm the adoption of trigonal pyramidal geometry for the copper(I) ion,* with all Cu---S distances (average of 3.344(4) A) being too great for any bonding interaction (Fig. I).* The cation has non~rystallographic three-fold symmetry, with the sulphur atoms being twisted
* Crystal data for C&H&UN&B, M, = 811.4, monoclinic, space group P2,/c, a = 11.774(l), b = 17.738(2), c = 22.917(4) A, fi = 121.08(I)“, V= 4099(3) A3, Z = 4, Mo-K= radiation (1= 0.71069 A, T = 298 K. A Gaussian absorption was applied (p = 7.39 cm-‘). The structure was solved by a combination of direct methods and difference Fourier synthesis. Successful refinement was by full-matrix least-squares with R = 0.046 and R, = 0.060 for 3996 reflections with I > 3rr(I). Pertinent bond distances and angles can be found in the text and in Table 2. A transformation of the coordinates from P2 Jc using the matrix -1
0
0 0
01 i -1
0
-1
1
will give a P2,/n monoclinic cell [a = 11.774(l), b = 17.738(2), c = 19.627(4) A, jJ = 90.17(l)“] which is isomorphous [BPh,]-. lo
with
[CuN(CH,CH2NsH-CsH5),]+
Fig. 1. A view of the [CuN(CH&JH,N=CH-C,H,S),]+ cation with the crystallographic numbering scheme ; ellipsoids are at the 50% level.
of 40.2” from being eclipsed with the equatorial nitrogen atoms ; an angle of 60” corresponds to a trigonal antiprism. The CL+--N distances to the equatorial nitrogens w(l), N(2), N(3)] are 2.028(S), 2.006(4) and 1.999(4) A, respectively, while the N(ap)---Cu-N(eq) and N(eq)---Cu -N(eq) angles are 82.1(2) and 118.2(2)’ (av.), respectively. The Cu-N(ap) distance is 2.310(5) A, with the copper atom being 0.275(l) 8, above the plane of the equatorial azomethine nitrogen atoms and the apical tertiary amine atom (N) lying 2.035(l) 8, below that plane. Other relevant interatomic distances and angles are given in Table 2. Not surprisingly, the coordination geometry is remarkedly similar to that recently described for the cationic copper(I) complex of the related tripodal Schiff base ligand N[~H~CH~N~H~C~H~)]~ (Ph,tren). lo Principal dimensions in that case were Cu-N(ap) 2.232(2) A, Cu-N(eq) 2.010(2) A (av) and N(ap)-Cu-N(eq) 84.2(l)’ (av), N(eq jCu -N(eq) 118.9” (av). The green complexes of formulation CuXZ * S$ren (X = Cl, Br) have similar structures to each other, with spectral evidence indicating six-coordination in the solid state and five-coordination in solution. IR spectra of the solids show coordination of the azomethine nitrogen atoms [v(C=N) shifts from 1637 to 1616 cm- ‘1,the presence of lattice water in the chloride [v(O-H) at 3396 cm- ‘1,and v(Cu-X) bands typical of octahedral geometry (240 and 209 cm- ’ for Cl and Br, respectively). Three g values are observed in the ESR spectra of powder samples (Table 3) with the ~nimum g value being less than 2.03, as is typical of distorted c&octahedral geometry. ’ ’ Freshly prepared frozen dimethylformamide solutions gave axial ESR spectra withgIl > $4,.(Table 2), suggesting a dx2_“2electronic ground state of square pyramidal an average
2466
E. C. ALYEA
Table 2. Molecular (a) Interatomic Cu-N Cu-N( 1) &--N(2) Cu-N(3) cu-S( 1) cu-S(2) cu-S( 3)
dimensions
distances
2.310(5) 2.027(5) 2.006(4) 1.999(4) 3.276(3) 3.361(4) 3.396(5) 1.71 l(7) 1.699(7) 1.705(7) 1.714(7) 1.706(6) 1.704(7)
S(l)_C(14) S(l)_C(17) S(2~(24) S(2)--c(27) S(3)_C(34) S(3)_C(37)
et al.
(A)
N-C(ll) N-C(21) N-C(3 1)
1.461(7) 1.456(7) 1.459(7) 1.482(7) 1.268(7) 1.475(6) 1.268(6) 1.472(7) 1.270(6) 1.515(8) 1.430(10) 1.516(8) 1.435(9) 1.496(9) 1.431(7)
N(l)_C(12) N(ljC(l3) N(2)--C(22) N(2)-~(23) N(3)---C(32) N(3)----C(33) c(ll)--c(l2) C(13)-C(l4) C(21)-C(22) C(23)--C(24) C(3 l)--c(32) C(33k--C(34) (b) Bond angles (“)
N-Cu-N( 1) N-&-N(2) N--G-N(3) N( 1)---Cu-N(2) N(l)-Cu-N(3) N(2)--Cu-N(3) Cu-N-C( 11) Cu-N-C(21) Cu-N-C(3 1) C( l l)-N-C(2 1) C(ll)--N-C(31) C(21)--N-C(31) Cu-N(l)---C(12) Cu-N(l)--C(l3) C(l2)--N(l)-C(13) Cu-N(2)-C(22) Cu-N(2)-C(23)
81.2(2) 82.8(2) 82.3(2) 110.9(2) 117.9(2) 125.5(2) 104.7(4) 102.8(4) 103.2(4) 114.6(5) 115.0(5) 114.5(5) 107.0(4) 134.8(4) 117.1(5) 107.9(4) 135.7(4) 116.0(5) 105.9(4) 136.9(4) 115.6(5)
C(22)-N(2)--c(23) Cu-N(3)-C(32) Cu-N(3tC(33) C(32)_N(3F-C(33)
Table 3. Electronic Compound CuCl, * S,tren CuBr, - S,tren
d-d Transitions
(cm- I)”
14,300(180), lO,OOO(sh) 14,500(220), lO,OOO(sh)
N-C(11
110.8(5) 109.2(5) 126.0(5) 123.2(6) 110.3(6) 126.6(6) 110.4(5) 110.3(5) 126.6(5) 123.9(6) 125.5(6) 111.1(5) 110.7(5) 126.2(5) 124.3(6) 124.4(6)
)-X(12)
N(l)_‘W9-W
1)
N(l)-C(l3WJl4) s(l)-C(14)-c(l3) s(l)--c(l4)-c(l5) c(l3)---c(l4)-C(l5) N-C(21)-C(22) N(2)-C(22)-C(21) N(2)_C(23)--C(24) S(2)-C(24)-C(23) C(23)-C(24)--C(25) N--X(3 1)--X(32) N(3)_C(32)--C(3 1) N(3)---C(33)--C(34) S(3)--c(34)-+33) C(33>--c(34F(35)
and ESR spectral data” g,”
gze
g;
S,ld
91d
2.21 2.20
2.16 2.15
2.02 2.02
2.22(154) 2.24(159)
1.96 2.05
’ Dimethylformamide solutions. ‘Molar extinction coefficient (E) is in parentheses, sh is shoulder. ’ Spin-Hamiltonian parameters for powders at room temperature. dSpin-Hamiltonian parameters for frozen solutions at 77 K. Hyperline (A,,) in units of 10m4 cm-’ are in parentheses.
coupling
constants
Heptadentate tripodal Schiff base ligands with Cu’ and Cu” geometry. ‘* Conductance data for 10e3 M DMF solutions (AM = 62.5 and 68.2 a-’ mol- ’ cm* for the chloride and bromide, respectively) are in agreement with the complexes being 1 : 1 electrolytes. I3 These fresh DMF solutions showed electronic spectral bands at 14,300 cm-’ (E = 180, Cl) and 14,500 cm- ’ (E = 220, Br), with low energy shoulders near 10,000 cm- ’ ; such visible absorption bands are expected for square pyramidal copper(I1) complexes. “3 ’ 4 Preliminary electronic and ESR spectral data for these and other CuX, * S,tren complexes currently under study indicate that octahedral to square pyramidal to trigonal bipyramidal structural changes can occur; these results will be reported elsewhere. Acknowledgements-The
authors thank NSERC Canada for operating grants and an infrastructure grant (E.C.A. and G.F.) and a CIDA Research Associateship (Z.X.).
REFERENCES 1. M. G. B. Drew, Prog. Znorg. Chem. 1977,23,67. 2. D. L. Kepert, Prog. Znorg. Chem. 1979,25,41. 3. M. Calligaris and L. Randaccio, in Comprehensive Coordination Chemistrv (Edited bv G. Wilkinson. R.
2467
D. Gillard and J. A. McCleverty), Vol. 2, Ch. 20, p. 735. Pergamon Press, Oxford (1987). 4. L. J. Wilson and N. J. Rose, J. Am. Chem. Sot. 1968, !Ml,6041. 5. R. M. Kirchner, C. Mealli, M. Bailey, N. Howe, L. P. Torre, L. J. Wilson, L. C. Andrews, N. J. Rose and E. C. Lingafelter, Coord. Chem. Rev. 1987, 77, 89.
6. K. D. Karlin and J. Zubieta (Eds), Copper Coordination Chemistry : Biochemical & Inorganic Perspectives. Adenine Press, Guilderland, N.Y. (1983). 7. E. C. Alyea, S. Liu, B. Li, Z. Xu and X. Z. You, Acta Cryst. 1989, C45, 1566. 8. (a) F. A. Cotton and G. Wilkinson, Advanced Znorganic Chemistry, 4th edn, p. 800. John Wiley, New York (1980) ; (b) M. Suzuki, H. Kanatomi, H. Koyama and I. Murase, Bull. Chem. Sot. Jpn 1980, 53, 1961. 9. E. C. Alyea, G. Ferguson, M. Jennings, B. Li, Z. Xu and X. Z. You, unpublished results (1989). 10. E. C. Alyea, G. Ferguson, M. Jennings and Z. Xu, Polyhedron 1990,9,739. 11. B. J Hathaway and D. E. Billing, Coord. Chem. Rev. 1970, 5, 143. 12. T. N. Sorrel1 and D. L. Jameson, Znorg. Chem. 1982, 21, 1014.
13. W. J. Geary, Coord. Chem. Rev. 1971,7,81. 14. A. B. P. Lever, Inorganic Electronic Spectroscopy, 2nd edn. Elsevier, Amsterdam (1984).
Vol.
9, No.
20, pp.
2463-2467,
1990
0277-5387/90 S3.OOf.W 0 1990 Pergamon Press plc
Printed in Great Britain
SOME COPPER(I) AND COPPER@) COMPLEXES OF TWO NEW POTENTIALLY HEPTADENTATE TRIPODAL SCHIFF BASE LIGANDS ELMER C. ALYEA,* GEORGE FERGUSON
and MICHAEL
JENNINGS
Department of Chemistry and Biochemistry, University of Guelph, Guelph, Ontario N 1G 2W 1 Canada and BAOLONG
Coordination
LI, ZHENG
XU and XIAOZENG
YOU
Chemistry Institute, Nanjing University, Nanjing, P.R.C. and SIIIXIONG
LIU
Institute of Structural Chemistry, Fuzhou University, Fuzhou, P.R.C. (Received 27 September 1989; accepted 21 May 1990) Abstract-Two
potentially heptadentate tripodal Schiff base ligands, tris[4-(2-thienyl)-3aza-3-butenyllamine (S3tren) and tris[4-(2-furyl)-3-aza-3-butenyllamine (0,tren) have been prepared and characterized by ‘H and 13C NMR spectral data. For the complexes [Cu (E,tren)]BPh, (E = S, 0), NMR spectral shifts clearly indicate coordination of all four nitrogen donor atoms. X-ray analysis for [Cu(S,tren)]BPh, shows trigonal pyramidal geometry for the copper(I) cation, with all Co---S distances [average of 3.344(4) A] being too great for any bonding interaction. IR, ESR and electronic spectral data for the green copper(I1) complexes, CuX2 - S,tren (X = Cl, Br), indicate six-coordination in the solid state and square pyramidal geometry (with halide dissociation) in freshly prepared dimethylformamide solutions.
(1) PYstren
(2)
Although seven-coordination is readily achieved by many metal ions, ‘,2 the ability of a single ligand to supply all seven donor atoms is rare.3 The best studied potentially heptadentate ligand, tris[4-(2pyridyl)-3-aza-3-butenyllamine, known as py3tren (l), was designed to give transition metal complexes having mono-capped trigonal antiprismatic coordination polyhedra. 4*5 A recent detailed assessment of the bonding properties of py,tren in a
E = S, S3tren; (3) E = 0, O+en
series of [M(py3tren)]‘+ (M = Mn, Fe, Co, Ni, Cu and Zn) complexes shows, however, that the seventh bond to the apical or bridgehead nitrogen atom may only be considered as “weakly bonding” in the case of manganese [2.794(2) A] and cobalt [2.870(2) A]. ’ In order to overcome the domineering influence of the three pendant cl-diimine chelating arms on the resultant metal geometry, we have prepared two new analogous ligands that contain thiophene and furan moieties in the pendant arms. These potentially heptadentate tripodal Schiff base ligands, *Author to whom correspondence should be addressed. called S,tren (2) amd 0,tren (3) are expected to 2463
2464
E. C. ALYEA et al.
enhance metal interaction with the bridgehead nitrogen atom as compared to pyfren. 5The importance of multiden~~ nitrogen-s~ph~ ligands in copper model systems for the “blue” copper oxidases and electron transfer proteins6 led us to explore the coordinating ability of 2 and 3 with both copper(I) and copper(I1) ions, which we report in this paper. The syntheses of the new potentially heptadentate ligands 2 and 3 were readily effected by the Schiff base condensation of tris(2~aminoethyl)amine (tren) with the appropriate aldehyde. S,tren precipitated from the absolute ethanol solution as a white solid in 93% yield (m.p. 135-137°C) and gave satisfactory elemental analysis ; 0 $ren was isolated as an easily hydrolysed oil and thus was characterized by spectral methods. ‘H and i3C NMR spectral data (coupled and decoupled) acquired on a Bruker WH-400 spectrometer provided confirmatory evidence for the formation of the expected three azomethine linkages. The assignment of ‘H
and 13C resonances according to the above structural formula for 2 and 3 (Table 1) was based on those observed for the precursors. Characteristic mass spectral molecular ion and fR v(C=N) stretching frequencies occurred at 428 m/z,1637 ctn ’ (2) and at 380 m/z,1647 cm-’ (3). An X-ray crystallographic analysis of S,tren has confirmed the tripodal geometry of the ligand and revealed the conjugation of the thiophene moieties with the azomethine linkages7 The reactions of 2 with CuXZ salts gave [CuL]Y and CuX2 *L, where Y = I,, BPh4 and X = Cl, Br, N3, SCN, C104, NU3. The copper(I) complexes were obtained by the addition of excess NaY to solutions containing Cu(OAc)~ and L ; [~u(O~~en)] BPh4 was isolated in a similar fashion. Copper(I1) is well known to be easily converted to copper(I) by various mild reducing agents or ligands,‘” for example, the tripodal ligand tris(2-methylthioethyl)amine (N&-Me) forms [Cu(NS,-Me)]E, due to the instability of the initial copper(I1) com-
Tabie 1. ‘H and ’ ‘C NMR spectral data ‘I-I data” &(ppm) and J(Hz)
’ 3C data” ~~pprn~ and J(Hz)
S$renh
8.10 (H,), 7.36 (I-I,, d, Jcd = 5.2) 6.99 (H,, dd, Jti = 5.1, &, = 3.7), 6.69 (H,,, d, & = 3.7), 3.58 (H,, t, J,r = 5.7), 2.82 (I& t, J,r = 5.7)
155.29 (C,, d, J = 161.6), 142.73 (C,), 130.28 (C,, d, J = 176.7), 128.35 (C, d, J= 194.8), 127.28 (C,, d, J= 168.8), 59.58 (C,, t, J= 134.4), 55.67 (C,, t, J = 132.7)
0 #en”
7.91 (Ha), 6.45-6.42 (Hi,, H,, Hd, m). 3.63 (H,, t, & = 5.9), 2.88 (Hr. t, J,r = 6.1)
151.44 (C,,), 150.63 (C,, d, J = 161.6), 144.48 (C,, d, J = 202.6); 113.76 (&,d,J= 175.9); 111,51(C,,,d, J = 176.7): 59.71 (C,, t, J = 134.3), 55.35 (C, t, J = 133.1)
Compound
8.78 (Ha), 7.76 (H6, dd, Jbd = 3.7, J = 1.2), 7.63 (H,, d, Jcd = 5.2), 7?4 (H, phenyl, m), 7.18 (H,,, dd, Jcd = 5.2, Jbd = 3.7), 6.92 (H, phenyl, t, J = 7.4) 6.77 (H, phenyl, t, J = 7.3), 3.80 (II,, t, J = 5.3), 3.13 (Hf, t, J = 5.4) 8.33 (H,), 7.47 (Hi,, d, & = 1.4), 7.44 (H,, d, &, = 3.5), 7.34 (H, phenyl, t, J = 3.1), 6.92 (H, phenyl, t, J = ‘7.3), 6.77 (H, pbenyl, t, J = 7.2), 6.65 (Hd, dd, Jcd = 3.5, Jbd = 1.6), 3.81 (H,, dd, J = 5.9, J = 4.8), 3.16 (Hn dd, J = 6.3, J = 5.0) “d = doublet, dd = doublet of doublets, m = multiplet, t = triplet. ’ CDCl, solution. ‘Tentative assignment. ‘(CD,)&0 solution. e Insufficiency soluble.
Heptadentate tripodal Schiff base ligands with Cu’ and Cu”
2465
plex, [Cu(NS3-Me)I]C104.8b The isolation of [ML]
(OAc)(BPh,) complexes, where M = Mn, Fe, Co, Ni and L = 2 and 3, has also been accomplished and spectral and structural characterization is underway. ’ Preliminary ‘H NMR spectral data for [CuL]BPh,, where L = 2 and 3, and ESR and visible spectra data for CuX2 * S,tren, where X = Cl and Br, are presented here. Downfield shifts of proton resonances in the ‘H NMR spectra of [CuL]BPh, (L = 2 and 3), compared to those observed for the free ligands, clearly indicate coordination of all four nitrogen donor atoms. The shifts are the most dramatic for the azomethine protons [(H,) 0.68 (2) vs 0.42 (3) ppm] and ethylene protons [0.22, 0.31 (2) vs 0.18, 0.29 ppm (3) for H, and Hf, respectively]. Resonances due to ring protons are also shifted downfield in the complexes (Table I), but it is less clear whether this occurs due to E atom complexation. The large shift for H,, (1.07 and 1.03 ppm for 2 and 3, respectively) could occur simply as a result of increased conjugation with the C&N linkage ; the shift of only ca 0.2 ppm, which occurs for Hd in both complexes, supports this idea rather than coordination of the E atoms. However, the shift for H, is much larger for 3 (1 .Ol vs 0.27 ppm for 2), implying that the Cu-0 interaction is significantly greater than the Cu-S interaction. X-ray investigations are underway to resolve this ambi~ity ; results for [CuL]BPh, (L = 2) confirm the adoption of trigonal pyramidal geometry for the copper(I) ion,* with all Cu---S distances (average of 3.344(4) A) being too great for any bonding interaction (Fig. I).* The cation has non~rystallographic three-fold symmetry, with the sulphur atoms being twisted
* Crystal data for C&H&UN&B, M, = 811.4, monoclinic, space group P2,/c, a = 11.774(l), b = 17.738(2), c = 22.917(4) A, fi = 121.08(I)“, V= 4099(3) A3, Z = 4, Mo-K= radiation (1= 0.71069 A, T = 298 K. A Gaussian absorption was applied (p = 7.39 cm-‘). The structure was solved by a combination of direct methods and difference Fourier synthesis. Successful refinement was by full-matrix least-squares with R = 0.046 and R, = 0.060 for 3996 reflections with I > 3rr(I). Pertinent bond distances and angles can be found in the text and in Table 2. A transformation of the coordinates from P2 Jc using the matrix -1
0
0 0
01 i -1
0
-1
1
will give a P2,/n monoclinic cell [a = 11.774(l), b = 17.738(2), c = 19.627(4) A, jJ = 90.17(l)“] which is isomorphous [BPh,]-. lo
with
[CuN(CH,CH2NsH-CsH5),]+
Fig. 1. A view of the [CuN(CH&JH,N=CH-C,H,S),]+ cation with the crystallographic numbering scheme ; ellipsoids are at the 50% level.
of 40.2” from being eclipsed with the equatorial nitrogen atoms ; an angle of 60” corresponds to a trigonal antiprism. The CL+--N distances to the equatorial nitrogens w(l), N(2), N(3)] are 2.028(S), 2.006(4) and 1.999(4) A, respectively, while the N(ap)---Cu-N(eq) and N(eq)---Cu -N(eq) angles are 82.1(2) and 118.2(2)’ (av.), respectively. The Cu-N(ap) distance is 2.310(5) A, with the copper atom being 0.275(l) 8, above the plane of the equatorial azomethine nitrogen atoms and the apical tertiary amine atom (N) lying 2.035(l) 8, below that plane. Other relevant interatomic distances and angles are given in Table 2. Not surprisingly, the coordination geometry is remarkedly similar to that recently described for the cationic copper(I) complex of the related tripodal Schiff base ligand N[~H~CH~N~H~C~H~)]~ (Ph,tren). lo Principal dimensions in that case were Cu-N(ap) 2.232(2) A, Cu-N(eq) 2.010(2) A (av) and N(ap)-Cu-N(eq) 84.2(l)’ (av), N(eq jCu -N(eq) 118.9” (av). The green complexes of formulation CuXZ * S$ren (X = Cl, Br) have similar structures to each other, with spectral evidence indicating six-coordination in the solid state and five-coordination in solution. IR spectra of the solids show coordination of the azomethine nitrogen atoms [v(C=N) shifts from 1637 to 1616 cm- ‘1,the presence of lattice water in the chloride [v(O-H) at 3396 cm- ‘1,and v(Cu-X) bands typical of octahedral geometry (240 and 209 cm- ’ for Cl and Br, respectively). Three g values are observed in the ESR spectra of powder samples (Table 3) with the ~nimum g value being less than 2.03, as is typical of distorted c&octahedral geometry. ’ ’ Freshly prepared frozen dimethylformamide solutions gave axial ESR spectra withgIl > $4,.(Table 2), suggesting a dx2_“2electronic ground state of square pyramidal an average
2466
E. C. ALYEA
Table 2. Molecular (a) Interatomic Cu-N Cu-N( 1) &--N(2) Cu-N(3) cu-S( 1) cu-S(2) cu-S( 3)
dimensions
distances
2.310(5) 2.027(5) 2.006(4) 1.999(4) 3.276(3) 3.361(4) 3.396(5) 1.71 l(7) 1.699(7) 1.705(7) 1.714(7) 1.706(6) 1.704(7)
S(l)_C(14) S(l)_C(17) S(2~(24) S(2)--c(27) S(3)_C(34) S(3)_C(37)
et al.
(A)
N-C(ll) N-C(21) N-C(3 1)
1.461(7) 1.456(7) 1.459(7) 1.482(7) 1.268(7) 1.475(6) 1.268(6) 1.472(7) 1.270(6) 1.515(8) 1.430(10) 1.516(8) 1.435(9) 1.496(9) 1.431(7)
N(l)_C(12) N(ljC(l3) N(2)--C(22) N(2)-~(23) N(3)---C(32) N(3)----C(33) c(ll)--c(l2) C(13)-C(l4) C(21)-C(22) C(23)--C(24) C(3 l)--c(32) C(33k--C(34) (b) Bond angles (“)
N-Cu-N( 1) N-&-N(2) N--G-N(3) N( 1)---Cu-N(2) N(l)-Cu-N(3) N(2)--Cu-N(3) Cu-N-C( 11) Cu-N-C(21) Cu-N-C(3 1) C( l l)-N-C(2 1) C(ll)--N-C(31) C(21)--N-C(31) Cu-N(l)---C(12) Cu-N(l)--C(l3) C(l2)--N(l)-C(13) Cu-N(2)-C(22) Cu-N(2)-C(23)
81.2(2) 82.8(2) 82.3(2) 110.9(2) 117.9(2) 125.5(2) 104.7(4) 102.8(4) 103.2(4) 114.6(5) 115.0(5) 114.5(5) 107.0(4) 134.8(4) 117.1(5) 107.9(4) 135.7(4) 116.0(5) 105.9(4) 136.9(4) 115.6(5)
C(22)-N(2)--c(23) Cu-N(3)-C(32) Cu-N(3tC(33) C(32)_N(3F-C(33)
Table 3. Electronic Compound CuCl, * S,tren CuBr, - S,tren
d-d Transitions
(cm- I)”
14,300(180), lO,OOO(sh) 14,500(220), lO,OOO(sh)
N-C(11
110.8(5) 109.2(5) 126.0(5) 123.2(6) 110.3(6) 126.6(6) 110.4(5) 110.3(5) 126.6(5) 123.9(6) 125.5(6) 111.1(5) 110.7(5) 126.2(5) 124.3(6) 124.4(6)
)-X(12)
N(l)_‘W9-W
1)
N(l)-C(l3WJl4) s(l)-C(14)-c(l3) s(l)--c(l4)-c(l5) c(l3)---c(l4)-C(l5) N-C(21)-C(22) N(2)-C(22)-C(21) N(2)_C(23)--C(24) S(2)-C(24)-C(23) C(23)-C(24)--C(25) N--X(3 1)--X(32) N(3)_C(32)--C(3 1) N(3)---C(33)--C(34) S(3)--c(34)-+33) C(33>--c(34F(35)
and ESR spectral data” g,”
gze
g;
S,ld
91d
2.21 2.20
2.16 2.15
2.02 2.02
2.22(154) 2.24(159)
1.96 2.05
’ Dimethylformamide solutions. ‘Molar extinction coefficient (E) is in parentheses, sh is shoulder. ’ Spin-Hamiltonian parameters for powders at room temperature. dSpin-Hamiltonian parameters for frozen solutions at 77 K. Hyperline (A,,) in units of 10m4 cm-’ are in parentheses.
coupling
constants
Heptadentate tripodal Schiff base ligands with Cu’ and Cu” geometry. ‘* Conductance data for 10e3 M DMF solutions (AM = 62.5 and 68.2 a-’ mol- ’ cm* for the chloride and bromide, respectively) are in agreement with the complexes being 1 : 1 electrolytes. I3 These fresh DMF solutions showed electronic spectral bands at 14,300 cm-’ (E = 180, Cl) and 14,500 cm- ’ (E = 220, Br), with low energy shoulders near 10,000 cm- ’ ; such visible absorption bands are expected for square pyramidal copper(I1) complexes. “3 ’ 4 Preliminary electronic and ESR spectral data for these and other CuX, * S,tren complexes currently under study indicate that octahedral to square pyramidal to trigonal bipyramidal structural changes can occur; these results will be reported elsewhere. Acknowledgements-The
authors thank NSERC Canada for operating grants and an infrastructure grant (E.C.A. and G.F.) and a CIDA Research Associateship (Z.X.).
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