(-)-Sparteine copper(II) diacetate

The chiral nitrogen-chelating alkaloid (-)-sparteine acts as a bidentate ligand, reacting with copper(II) acetate in ethanol to form the title complex, [Cu(CH₃COO)₂(C₁₅H₂₆N₂)], with the two acetate groups occupying the remaining coordination sites in a monodentate fashion to produce a distorted four-coordinate tetrahedral structure. The dihedral angle between the N-Cu-N and O-Cu-O planes is 45.8 (3)°.

S1. Comment

Previously, we determined the crystal structures of (-)-sparteine copper(II) dinitrate and (-)-sparteine copper(II) dinitrite (Choi et al., 1995; Lee, Choi et al., 1998). The molecules of (-)-sparteine copper(II) dinitrate are mixed, with both four- and five-coordinates in one crystalline phase and only the four-coordinate species in the other (Choi et al., 1995). However, the copper(II) ion in (-)-sparteine copper(II) dinitrite is exclusively five-coordinate, with a highly distorted square-pyramidal geometry (Lee & Choi et al., 1998). The acetate ion, like the nitrate or nitrite ions, can coordinate to a metal in either a mono- or a bidentate fashion, and we expected that (-)-sparteine copper(II) diacetate, (I), might show either a four- or five-coordinate geometry around the copper(II) ion. The copper(II) ion in this complex is found to be exclusively four-coordinate, with a distorted tetrahedral geometry.

The N1—Cu—N9 plane in (I) is twisted by 45.8 (3)° from the O1—Cu—O3 plane. The respective bond lengths of Cu—O1 and Cu—O3 are 1.927 (5) and 1.973 (4) Å, and these values are similar to those found in strongly coordinated anions (Togni et al., 1990; Choi et al., 1995; Lopez et al., 1998; Lee, Choi et al., 1998; Lee, Oh et al., 1998). The Cu···O2 and Cu···O4 distances, which are 3.061 (5) and 2.701 (5) Å respectively, are too well separated to be considered as bonding interactions. The Cu—N bond distances of 2.010 (6) and 2.049 (6) Å are comparable to those found in other (-)-sparteine copper(II) complexes (Togni et al., 1990; Choi et al., 1995; Lopez et al., 1998; Lee, Choi et al., 1998).

The O—C—O bond angles in (I) are observed to be 124.9 (8)° and 124.0 (5)°, and these are similar to the value in the free acetate (Hsu & Nordman, 1983) and are much greater than the O—N—O bond angles of coordinated nitrates or nitrites (Choi et al., 1995; Lee, Choi et al., 1998). Furthermore, if the acetate ion chelates to the copper(II) centre, double-bond character will be developed at the endo-position of the chelate ring and this will require the O—C—O bond angle to be more open. The chelated acetate will cause greater ring strain than the chelated nitrite or nitrate does. As a result, the acetate seems to prefer to coordinate to the copper(II) ion in a monodentate fashion.

S2. Experimental

Complex (I) was prepared by the direct reaction of copper(II) acetate with a stoichiometric amount of (-)-sparteine in ethanol-triethylorthoformate (5:1 v/v) solution. Single crystals were obtained by recrystallization at about 278 K from a dichloromethane-triethylorthoformate (4:1 v/v) solution under carbon tetrachloride vapor.

S3. Refinement

All non-H atoms were found by direct methods, and their parameters were refined successfully with a full matrix least-squares procedure. H atoms were geometrically positioned and fixed.

Computing details

Data collection: CAD-4 Software (Enraf-Nonius, 1989); cell refinement: CAD-4 Software (Enraf-Nonius, 1989); data reduction: Xtal3.2 Reference Manual (Hall et al., 1992); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ZORTEP (Zsolnai, 1996); software used to prepare material for publication: SHELXL97.

Figures

Fig. 1. ZORTEP (Zsolnai, 1996) diagram of (I), showing the atom-numbering scheme and 40% probability ellipsoids. H atoms are omitted for clarity.

{1,3,4,7,7a,8,9,10,11,13,14,14a-dodecahydro-7,14-methano- 2H,6H-dipyrido[1,2 − a:1',2'-e][1,5]diazocine-N,N'}bis(acetato- O,O')copper(II)

Crystal data

[Cu(C2H3O2)2(C15H26N2)]	F(000) = 442
Mr = 416.01	Dx = 1.393 Mg m^−3
Monoclinic, P21	Mo Kα radiation, λ = 0.71069 Å
a = 8.0507 (8) Å	Cell parameters from 25 reflections
b = 12.0791 (12) Å	θ = 7.3–13.0°
c = 10.2946 (8) Å	µ = 1.13 mm^−1
β = 97.954 (8)°	T = 293 K
V = 991.47 (16) Å^3	Cube, blue
Z = 2	0.60 × 0.45 × 0.25 mm

Data collection

Enraf-Nonius CAD-4 diffractometer	1626 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.020
Graphite monochromator	θmax = 25.0°, θmin = 2.0°
ω scans	h = 0→9
Absorption correction: ψ scan (North et al., 1968)	k = −2→14
Tmin = 0.543, Tmax = 0.754	l = −12→12
2013 measured reflections	3 standard reflections every 3600 min
1838 independent reflections	intensity decay: none

Refinement

Refinement on F^2	H-atom parameters constrained
Least-squares matrix: full	Calculated w = 1/[σ^2(Fo^2) + (0.0136P)^2 + 1.9871P] where P = (Fo^2 + 2Fc^2)/3
R[F^2 > 2σ(F^2)] = 0.042	(Δ/σ)max < 0.001
wR(F^2) = 0.101	Δρmax = 0.37 e Å^−3
S = 1.32	Δρmin = −0.51 e Å^−3
1838 reflections	Absolute structure: Flack (1983)
230 parameters	Absolute structure parameter: −0.03 (3)
1 restraint

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Cu	0.52306 (8)	0.05527 (7)	0.14475 (6)	0.0353 (2)
N1	0.2910 (7)	−0.0060 (5)	0.0938 (6)	0.0400 (13)
N9	0.5557 (7)	−0.0463 (6)	0.3057 (6)	0.0432 (14)
C2	0.2049 (8)	0.0495 (10)	−0.0262 (6)	0.0498 (17)
H2A	0.0951	0.0165	−0.0503	0.060*
H2B	0.2692	0.0379	−0.0980	0.060*
C3	0.1856 (11)	0.1715 (8)	−0.0043 (9)	0.064 (2)
H3A	0.1295	0.2055	−0.0839	0.077*
H3B	0.2955	0.2052	0.0163	0.077*
C4	0.0843 (10)	0.1916 (8)	0.1074 (9)	0.063 (2)
H4A	0.0820	0.2702	0.1261	0.076*
H4B	−0.0302	0.1670	0.0817	0.076*
C5	0.1602 (12)	0.1299 (8)	0.2295 (10)	0.053 (2)
H5A	0.0885	0.1383	0.2972	0.064*
H5B	0.2688	0.1615	0.2619	0.064*
C6	0.1809 (11)	0.0073 (7)	0.2011 (9)	0.042 (2)
H6	0.0697	−0.0217	0.1670	0.051*
C7	0.2482 (9)	−0.0617 (7)	0.3210 (7)	0.0477 (18)
H7	0.1691	−0.0534	0.3846	0.057*
C8	0.3742 (10)	−0.1925 (7)	0.1845 (7)	0.0499 (19)
H8	0.3764	−0.2702	0.1574	0.060*
C10	0.7244 (9)	−0.0206 (9)	0.3780 (7)	0.057 (2)
H10A	0.7182	0.0492	0.4239	0.069*
H10B	0.8024	−0.0110	0.3151	0.069*
C11	0.7929 (11)	−0.1083 (10)	0.4764 (8)	0.072 (3)
H11A	0.9052	−0.0879	0.5156	0.087*
H11B	0.7229	−0.1123	0.5458	0.087*
C12	0.7977 (12)	−0.2205 (10)	0.4117 (9)	0.079 (3)
H12A	0.8760	−0.2189	0.3482	0.095*
H12B	0.8354	−0.2760	0.4773	0.095*
C13	0.6264 (12)	−0.2498 (9)	0.3447 (9)	0.069 (3)
H13A	0.5532	−0.2609	0.4109	0.083*
H13B	0.6331	−0.3194	0.2987	0.083*
C14	0.5482 (10)	−0.1632 (7)	0.2475 (7)	0.0441 (17)
H14	0.6177	−0.1615	0.1765	0.053*
C15	0.4225 (9)	−0.0297 (8)	0.3915 (7)	0.0504 (19)
H15A	0.4214	0.0474	0.4179	0.060*
H15B	0.4483	−0.0742	0.4701	0.060*
C16	0.3099 (10)	−0.1258 (6)	0.0648 (8)	0.0496 (19)
H16A	0.3866	−0.1339	0.0006	0.060*
H16B	0.2020	−0.1551	0.0265	0.060*
C17	0.2487 (10)	−0.1836 (7)	0.2835 (9)	0.055 (2)
H17A	0.1378	−0.2070	0.2441	0.066*
H17B	0.2839	−0.2291	0.3600	0.066*
C18	0.6499 (10)	0.2447 (8)	0.2835 (8)	0.0513 (19)
C19	0.7790 (9)	0.3333 (7)	0.3132 (7)	0.070 (3)
H19A	0.7245	0.4028	0.3232	0.106*
H19B	0.8449	0.3384	0.2425	0.106*
H19C	0.8506	0.3155	0.3929	0.106*
C20	0.6865 (6)	0.0045 (5)	−0.0544 (5)	0.0395 (16)
C21	0.7282 (7)	−0.0045 (5)	−0.1936 (4)	0.069 (3)
H21A	0.8384	0.0247	−0.1970	0.103*
H21B	0.6477	0.0370	−0.2518	0.103*
H21C	0.7246	−0.0808	−0.2200	0.103*
O1	0.6750 (7)	0.1758 (5)	0.1956 (5)	0.0573 (15)
O2	0.5343 (8)	0.2397 (7)	0.3496 (8)	0.085 (2)
O3	0.5602 (5)	0.0652 (7)	−0.0404 (4)	0.0472 (11)
O4	0.7681 (7)	−0.0461 (5)	0.0346 (5)	0.0571 (14)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cu	0.0352 (4)	0.0414 (4)	0.0303 (3)	−0.0042 (5)	0.0084 (3)	−0.0029 (5)
N1	0.036 (3)	0.044 (3)	0.040 (3)	0.000 (3)	0.006 (2)	−0.005 (3)
N9	0.040 (3)	0.054 (4)	0.037 (3)	0.000 (3)	0.011 (3)	0.002 (3)
C2	0.039 (3)	0.061 (5)	0.046 (3)	0.005 (5)	−0.005 (3)	0.001 (6)
C3	0.056 (5)	0.066 (6)	0.068 (6)	0.005 (5)	0.004 (4)	0.018 (5)
C4	0.043 (4)	0.058 (5)	0.089 (6)	0.010 (4)	0.010 (4)	0.002 (5)
C5	0.045 (5)	0.052 (5)	0.066 (6)	−0.002 (4)	0.019 (4)	−0.007 (5)
C6	0.029 (4)	0.047 (4)	0.052 (5)	−0.005 (3)	0.007 (3)	0.002 (4)
C7	0.040 (4)	0.056 (5)	0.049 (4)	−0.005 (4)	0.017 (3)	0.009 (4)
C8	0.062 (5)	0.041 (4)	0.049 (4)	0.000 (4)	0.017 (4)	0.005 (4)
C10	0.037 (4)	0.098 (7)	0.036 (4)	−0.003 (4)	−0.001 (3)	−0.003 (4)
C11	0.055 (5)	0.113 (9)	0.048 (5)	0.017 (6)	0.005 (4)	0.013 (6)
C12	0.071 (6)	0.111 (9)	0.056 (5)	0.041 (6)	0.016 (5)	0.034 (6)
C13	0.083 (6)	0.071 (6)	0.059 (5)	0.026 (5)	0.033 (5)	0.021 (5)
C14	0.051 (4)	0.049 (5)	0.035 (4)	0.006 (4)	0.020 (3)	0.005 (3)
C15	0.056 (4)	0.067 (5)	0.031 (3)	−0.003 (4)	0.018 (3)	−0.013 (4)
C16	0.053 (4)	0.045 (4)	0.050 (4)	−0.006 (4)	0.005 (4)	−0.015 (4)
C17	0.052 (5)	0.049 (5)	0.070 (5)	−0.009 (4)	0.026 (4)	0.009 (4)
C18	0.047 (4)	0.058 (5)	0.048 (4)	−0.014 (4)	0.005 (4)	−0.006 (4)
C19	0.080 (6)	0.076 (7)	0.058 (5)	−0.031 (5)	0.020 (5)	−0.031 (5)
C20	0.048 (4)	0.040 (4)	0.032 (3)	−0.005 (3)	0.011 (3)	−0.002 (3)
C21	0.082 (6)	0.087 (7)	0.042 (4)	0.020 (5)	0.025 (4)	−0.007 (5)
O1	0.066 (3)	0.061 (4)	0.050 (3)	−0.023 (3)	0.024 (3)	−0.021 (3)
O2	0.063 (4)	0.092 (5)	0.110 (6)	−0.022 (4)	0.047 (4)	−0.038 (5)
O3	0.052 (2)	0.055 (3)	0.035 (2)	0.005 (4)	0.0124 (18)	0.002 (3)
O4	0.068 (4)	0.057 (4)	0.047 (3)	0.005 (3)	0.008 (3)	0.003 (3)

Geometric parameters (Å, º)

Cu—O1	1.927 (5)	C7—C17	1.522 (12)
Cu—O3	1.973 (4)	C7—C15	1.538 (10)
Cu—N1	2.010 (6)	C8—C14	1.503 (11)
Cu—N9	2.049 (6)	C8—C16	1.503 (11)
N1—C2	1.489 (9)	C8—C17	1.535 (10)
N1—C16	1.491 (9)	C10—C11	1.516 (12)
N1—C6	1.517 (10)	C11—C12	1.513 (15)
N9—C10	1.488 (9)	C12—C13	1.496 (14)
N9—C15	1.494 (8)	C13—C14	1.523 (11)
N9—C14	1.531 (10)	C18—O2	1.229 (9)
C2—C3	1.502 (15)	C18—O1	1.266 (10)
C3—C4	1.519 (12)	C18—C19	1.493 (9)
C4—C5	1.515 (13)	C20—O4	1.216 (8)
C5—C6	1.523 (11)	C20—O3	1.278 (7)
C6—C7	1.526 (11)	C20—C21	1.5201 (12)
O1—Cu—O3	92.4 (3)	C17—C7—C6	109.7 (7)
O1—Cu—N1	151.8 (2)	C17—C7—C15	109.2 (7)
O3—Cu—N1	91.7 (2)	C6—C7—C15	116.3 (6)
O1—Cu—N9	103.1 (3)	C14—C8—C16	115.0 (6)
O3—Cu—N9	142.9 (3)	C14—C8—C17	110.9 (7)
N1—Cu—N9	90.1 (2)	C16—C8—C17	108.9 (7)
C2—N1—C16	108.6 (7)	N9—C10—C11	114.2 (8)
C2—N1—C6	107.7 (6)	C12—C11—C10	111.2 (7)
C16—N1—C6	109.5 (6)	C13—C12—C11	109.7 (8)
C2—N1—Cu	111.1 (5)	C12—C13—C14	114.3 (8)
C16—N1—Cu	107.0 (5)	C8—C14—C13	113.4 (7)
C6—N1—Cu	112.8 (5)	C8—C14—N9	111.7 (6)
C10—N9—C15	110.8 (6)	C13—C14—N9	112.7 (7)
C10—N9—C14	111.9 (6)	N9—C15—C7	111.7 (6)
C15—N9—C14	111.3 (6)	N1—C16—C8	112.9 (6)
C10—N9—Cu	106.6 (5)	C7—C17—C8	105.1 (6)
C15—N9—Cu	112.0 (5)	O2—C18—O1	124.9 (8)
C14—N9—Cu	104.0 (4)	O2—C18—C19	118.7 (7)
N1—C2—C3	111.3 (7)	O1—C18—C19	116.2 (6)
C2—C3—C4	110.3 (8)	O4—C20—O3	124.0 (5)
C5—C4—C3	110.6 (7)	O4—C20—C21	120.5 (3)
C4—C5—C6	111.2 (9)	O3—C20—C21	115.5 (3)
N1—C6—C5	109.4 (6)	C18—O1—Cu	122.2 (5)
N1—C6—C7	110.7 (7)	C20—O3—Cu	107.7 (4)
C5—C6—C7	114.3 (9)