Di­chloro­[trans-(1R,2R)-N,N,N',N'-tetra­methyl­cyclo­hexane-1,2-di­amine]copper(II)

In the crystal structure of the title compound, [CuCl₂(C₁₀H₂₂N₂)], the Cu^II atom adopts a distorted square-planar geometry, the basal plane of which is formed by two N atoms from the cyclo­hexane­di­amine ligand, with Cu-N distances of 2.052 (7) Å, and two Cl atoms with Cu-Cl distances of 2.247 (2) Å. A twofold axis of symmetry passes through the Cu atom, such that all other atoms are symmetry-related in pairs. The torsion angle of C-N-Cu-Cl is 174.9 (3)°. The cyclo­hexane ring is in a chair form.

Key indicators

• Single-crystal X-ray study
• T = 300 K
• Mean [sigma](C-C) = 0.012 Å
• R factor = 0.039
• wR factor = 0.151
• Data-to-parameter ratio = 18.4

checkCIF/PLATON results

No syntax errors found



Alert level A
PLAT052_ALERT_1_A (Proper) Absorption Correction Method Missing ..          ?
PLAT721_ALERT_1_A Bond    Calc     0.96987, Rep     1.00000, Dev.        0.03 Ang.
              C2   -H2A     1.555   1.555
PLAT721_ALERT_1_A Bond    Calc     0.96984, Rep     1.00000, Dev.        0.03 Ang.
              C2   -H2B     1.555   1.555
PLAT721_ALERT_1_A Bond    Calc     0.96966, Rep     1.00000, Dev.        0.03 Ang.
              C3   -H3B     1.555   1.555
PLAT721_ALERT_1_A Bond    Calc     0.96000, Rep     1.00000, Dev.        0.04 Ang.
              C4   -H4A     1.555   1.555
PLAT721_ALERT_1_A Bond    Calc     0.96014, Rep     1.00000, Dev.        0.04 Ang.
              C4   -H4B     1.555   1.555
PLAT721_ALERT_1_A Bond    Calc     0.96038, Rep     1.00000, Dev.        0.04 Ang.
              C4   -H4C     1.555   1.555
PLAT721_ALERT_1_A Bond    Calc     0.96003, Rep     1.00000, Dev.        0.04 Ang.
              C5   -H5A     1.555   1.555
PLAT721_ALERT_1_A Bond    Calc     0.96034, Rep     1.00000, Dev.        0.04 Ang.
              C5   -H5B     1.555   1.555
PLAT721_ALERT_1_A Bond    Calc     0.95956, Rep     1.00000, Dev.        0.04 Ang.
              C5   -H5C     1.555   1.555
PLAT722_ALERT_1_A Angle   Calc      107.28, Rep       99.10, Dev.        8.18 Deg.
              C2   -C1   -H1      1.555   1.555   1.555
PLAT722_ALERT_1_A Angle   Calc      109.46, Rep      115.50, Dev.        6.04 Deg.
              C1   -C2   -H2A     1.555   1.555   1.555
PLAT722_ALERT_1_A Angle   Calc      109.48, Rep      104.60, Dev.        4.88 Deg.
              C3   -C2   -H2A     1.555   1.555   1.555
PLAT722_ALERT_1_A Angle   Calc      109.51, Rep      112.70, Dev.        3.19 Deg.
              C3   -C2   -H2B     1.555   1.555   1.555
PLAT722_ALERT_1_A Angle   Calc      108.04, Rep      104.30, Dev.        3.74 Deg.
              H2A  -C2   -H2B     1.555   1.555   1.555
PLAT722_ALERT_1_A Angle   Calc      109.58, Rep      118.70, Dev.        9.12 Deg.
              C2   -C3   -H3A     1.555   1.555   1.555
PLAT722_ALERT_1_A Angle   Calc      109.50, Rep      116.30, Dev.        6.80 Deg.
              N    -C4   -H4A     1.555   1.555   1.555
PLAT722_ALERT_1_A Angle   Calc      109.44, Rep      116.20, Dev.        6.76 Deg.
              N    -C4   -H4B     1.555   1.555   1.555
PLAT722_ALERT_1_A Angle   Calc      109.52, Rep      102.00, Dev.        7.52 Deg.
              H4A  -C4   -H4C     1.555   1.555   1.555
PLAT722_ALERT_1_A Angle   Calc      109.43, Rep      101.40, Dev.        8.03 Deg.
              H4B  -C4   -H4C     1.555   1.555   1.555
PLAT722_ALERT_1_A Angle   Calc      109.48, Rep       95.30, Dev.       14.18 Deg.
              N    -C5   -H5A     1.555   1.555   1.555
PLAT722_ALERT_1_A Angle   Calc      109.50, Rep      117.90, Dev.        8.40 Deg.
              N    -C5   -H5C     1.555   1.555   1.555
PLAT722_ALERT_1_A Angle   Calc      109.42, Rep      134.50, Dev.       25.08 Deg.
              H5A  -C5   -H5B     1.555   1.555   1.555
PLAT722_ALERT_1_A Angle   Calc      109.48, Rep       87.10, Dev.       22.38 Deg.
              H5A  -C5   -H5C     1.555   1.555   1.555

Alert level B
PLAT057_ALERT_3_B Correction for Absorption Required   RT(exp)   =       1.27
PLAT721_ALERT_1_B Bond    Calc     0.97012, Rep     1.00000, Dev.        0.03 Ang.
              C3   -H3A     1.555   1.555

Alert level C
PLAT242_ALERT_2_C Check Low    U(eq) as Compared to Neighbors ....         Cu
PLAT341_ALERT_3_C Low Bond Precision on C-C bonds (x 1000) Ang ...         12
PLAT721_ALERT_1_C Bond    Calc     0.98054, Rep     1.00000, Dev.        0.02 Ang.
              C1   -H1      1.555   1.555
PLAT722_ALERT_1_C Angle   Calc      107.25, Rep      108.90, Dev.        1.65 Deg.
              N    -C1   -H1      1.555   1.555   1.555
PLAT722_ALERT_1_C Angle   Calc      109.41, Rep      108.30, Dev.        1.11 Deg.
              C1   -C2   -H2B     1.555   1.555   1.555
PLAT722_ALERT_1_C Angle   Calc      109.49, Rep      111.30, Dev.        1.81 Deg.
              N    -C4   -H4C     1.555   1.555   1.555
PLAT722_ALERT_1_C Angle   Calc      109.45, Rep      107.80, Dev.        1.65 Deg.
              H4A  -C4   -H4B     1.555   1.555   1.555

Alert level G
REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is
            correct. If it is not, please give the correct count in the
            _publ_section_exptl_refinement section of the submitted CIF.
           From the CIF: _diffrn_reflns_theta_max           25.93
           From the CIF: _reflns_number_total               1289
           Count of symmetry unique reflns          682
           Completeness (_total/calc)            189.00%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured       607
           Fraction of Friedel pairs measured     0.890
           Are heavy atom types Z>Si present          yes

  24 ALERT level A = In general: serious problem
   2 ALERT level B = Potentially serious problem
   7 ALERT level C = Check and explain
   1 ALERT level G = General alerts; check

  30 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   1 ALERT type 2 Indicator that the structure model may be wrong or deficient
   2 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion

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S1. Comment

Copper(I) complexes with biologically relevant amine or mixed pyridyl/amine donors ligands have attracted much attention in recent years as simple models for the biomimetic chemistry of copper-containing proteins, which bind or activate dioxygen (Tolman, 1997; Schindler, 2000; Solomon, 2001). trans-(1R,2R)-N,N,N',N'-Tetramethylcyclohexane-1,2-diamine (L) is of interest because of its preorganized nature for binding a single metal and its chirality. Under argon conditions, L stabilizes copper(I) as a mononuclear trigonal-planar complex, formulated as [LCu(CH₃CN)](OTf) (OTf is trifluoromethanesulfonate, which was isolated but has not been structurally characterized (Cole et al., 1996). Our attemps to isolate the [LCu(CH₃CN)]ClO₄ complex from the reaction of L with [Cu(CH₃CN)₄]ClO₄, resulted in a redox reaction, which produced the title compound, (I), as a major product. The molecular structure of (I) is shown in Fig. 1.

The copper(II) metal center resides at a special twofold symmetry site and displays a distorted square-planar coordination geometry. The Cu—Cl bond length is 2.247 (2) Å and Cu—N is 2.052 (7) Å. The bond angles of the Cu center are: N—Cu—Nⁱ 83.9 (4)°, N—Cu—Cl 93.4 (2)°, N—Cu—Clⁱ 170.6 (3)° and Cl—Cu—Clⁱ 90.7 (2)°. The torsion angle of C1—N—Cu—Cl is 174.9 (3)°. The packing diagram of (I) is illustrated in Fig. 2. As can be seen, the unit cell contains two distinct molecules of (I). According to the interatomic distances there are no hydrogen bonds between adjacent molecules.

S2. Experimental

trans-(1R,2R)-N,N,N',N'-Tetramethylcyclohexane-1,2-diamine was synthesized from commercially available (1R)-trans-1,2-cyclohexanediamine (Aldrich) using the Eschweiler–Clark methylation of amines method (Remenar et al., 1997). [Cu(CH₃CN)₄]ClO₄ was prepared according to a published procedure (Gill et al., 1995). Equimolar amount of [Cu(CH₃CN)₄]ClO₄ (0.05 g, 0.15 mmol) and L (0.028 ml, 0.15 mmol) were combined in a 10 ml of a dry CH₃CN/CH₂Cl₂ (3:1, v/v) mixture under argon. The resulting colorless solution turned blue–green, while stirring for 1 d at room temperature under argon. The products were tprecipitated with 50 ml of dry diethyl ether to give 0.30 g (66%) of a blue–green powder. Recrystallization from a dichloromethane/acetonitrile (4:1, v/v) mixture, followed by slow diffusion of cyclohexane into a CH₃CN solution, afforded dark-blue crystals of the title compound, (I).

Computing details

Data collection: CAD-4 EXPRESS (Enraf-Nonius, 1994); cell refinement: CAD-4 EXPRESS; data reduction: XCAD4 (Harms & Wocadlo, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures

Fig. 1. The molecular structure of (I), with 30% probability displacement ellipsoids, showing the atom-numbering scheme employed. H atoms are shown as small spheres of the arbitrary radii. Fig. 2. The packing diagram for (I), viewed along the c axis. H atoms have been ommited for clarity.

Dichloro[trans-(1R,2R)-N,N,N',N'-tetramethylcyclohexane-1,2-diamine]copper(II)

Crystal data

[CuCl2(C10H22N2)]	F(000) = 318
Mr = 304.74	Dx = 1.528 Mg m^−3
Monoclinic, C2	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: C 2y	Cell parameters from 24 reflections
a = 8.8574 (8) Å	θ = 8.7–17.1°
b = 10.595 (1) Å	µ = 2.03 mm^−1
c = 8.0634 (5) Å	T = 300 K
β = 118.939 (6)°	Prismatic, dark blue
V = 662.2 (1) Å^3	0.44 × 0.31 × 0.25 mm
Z = 2

Data collection

Enraf-Nonius TurboCAD-4 diffractometer	1225 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.09
Graphite monochromator	θmax = 25.9°, θmin = 2.9°
non–profiled ω/2θ scans	h = −10→9
Absorption correction: ψ scan (North et al., 1968)	k = −12→12
Tmin = 0.481, Tmax = 0.603	l = 0→9
1379 measured reflections	2 standard reflections every 60 min
1289 independent reflections	intensity decay: 4%

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.039	H-atom parameters not refined
wR(F^2) = 0.151	w = 1/[σ^2(Fo^2) + (0.0748P)^2 + 6.5193P] where P = (Fo^2 + 2Fc^2)/3
S = 1.02	(Δ/σ)max < 0.001
1289 reflections	Δρmax = 0.54 e Å^−3
70 parameters	Δρmin = −0.66 e Å^−3
1 restraint	Absolute structure: Flack (1983)
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: −0.04 (5)

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	1.0000	0.78932 (10)	1.0000	0.0326 (4)
Cl	0.9030 (6)	0.64034 (19)	0.7735 (4)	0.0741 (12)
N	0.8845 (11)	0.9334 (6)	0.8097 (10)	0.0304 (15)
C1	0.9094 (8)	1.0539 (6)	0.9134 (9)	0.0305 (14)
H1	0.8263	1.0551	0.9609	0.037*
C2	0.8805 (11)	1.1746 (8)	0.7960 (12)	0.050 (2)
H2A	0.9591	1.1755	0.7442	0.060*
H2B	0.7636	1.1752	0.6910	0.060*
C3	0.9097 (9)	1.2909 (12)	0.9165 (11)	0.0548 (18)
H3A	0.8930	1.3659	0.8405	0.082*
H3B	0.8264	1.2929	0.9619	0.082*
C4	0.6974 (9)	0.9123 (8)	0.6817 (10)	0.0441 (18)
H4A	0.6505	0.9820	0.5955	0.066*
H4B	0.6393	0.9055	0.7556	0.066*
H4C	0.6814	0.8357	0.6114	0.066*
C5	0.9686 (11)	0.9368 (9)	0.6849 (12)	0.0486 (19)
H5A	0.9181	1.0032	0.5932	0.073*
H5B	0.9508	0.8574	0.6206	0.073*
H5C	1.0900	0.9519	0.7616	0.073*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cu	0.0299 (5)	0.0320 (6)	0.0300 (6)	0.000	0.0099 (4)	0.000
Cl	0.104 (3)	0.0439 (15)	0.0505 (16)	−0.0036 (15)	0.0186 (16)	−0.0174 (11)
N	0.033 (3)	0.035 (3)	0.017 (3)	0.001 (3)	0.007 (3)	0.000 (2)
C1	0.024 (3)	0.035 (4)	0.028 (3)	0.003 (2)	0.009 (3)	0.004 (3)
C2	0.042 (4)	0.045 (5)	0.050 (5)	0.008 (3)	0.012 (4)	0.019 (4)
C3	0.053 (4)	0.038 (3)	0.078 (5)	0.003 (7)	0.035 (4)	0.011 (7)
C4	0.027 (4)	0.063 (5)	0.028 (4)	−0.003 (3)	0.002 (3)	0.005 (3)
C5	0.044 (4)	0.063 (5)	0.041 (4)	0.007 (4)	0.022 (4)	0.000 (4)

Geometric parameters (Å, º)

Cu—N^i	2.052 (7)	C1—H1	1.00
Cu—N	2.052 (7)	C2—H2A	1.00
Cu—Cl	2.247 (2)	C2—H2B	1.00
Cu—Cl^i	2.247 (2)	C3—H3A	1.00
N—C1	1.483 (9)	C3—H3B	1.00
N—C4	1.486 (10)	C4—H4A	1.00
N—C5	1.515 (10)	C4—H4B	1.00
C1—C2	1.537 (9)	C4—H4C	1.00
C1—C1^i	1.535 (12)	C5—H5A	1.00
C2—C3	1.513 (15)	C5—H5B	1.00
C3—C3^i	1.512 (15)	C5—H5C	1.00
N^i—Cu—N	83.9 (4)	C1—C2—H2A	115.5
N^i—Cu—Cl	170.6 (3)	C1—C2—H2B	108.3
N—Cu—Cl	93.36 (17)	C3—C2—H2A	104.6
N^i—Cu—Cl^i	93.36 (17)	C3—C2—H2B	112.7
N—Cu—Cl^i	170.6 (3)	H2A—C2—H2B	104.3
Cl—Cu—Cl^i	90.73 (16)	C2—C3—H3A	118.7
C1—N—C4	109.4 (6)	C2—C3—H3B	110.2
C1—N—C5	111.6 (6)	N—C4—H4A	116.3
C4—N—C5	106.5 (6)	N—C4—H4B	116.2
C1—N—Cu	109.5 (5)	N—C4—H4C	111.3
C4—N—Cu	113.1 (5)	H4A—C4—H4B	107.8
C5—N—Cu	106.7 (5)	H4A—C4—H4C	102.0
N—C1—C2	115.7 (6)	H4B—C4—H4C	101.4
N—C1—C1^i	108.5 (5)	N—C5—H5A	95.3
C2—C1—C1^i	110.4 (5)	N—C5—H5B	110.1
C3—C2—C1	110.9 (7)	N—C5—H5C	117.9
C3^i—C3—C2	110.5 (5)	H5A—C5—H5B	134.5
N—C1—H1	108.9	H5A—C5—H5C	87.1
C2—C1—H1	99.1

Symmetry code: (i) −x+2, y, −z+2.