Bis[2-(methyl­amino)­troponato]copper(II)

In the title compound, [Cu(C₈H₈NO)₂], a strictly square-planar geometry about the Cu^II metal atom is observed. Substitution of an O atom with a methyl-functionalized N atom does not significantly alter the bond distances and angles in the copper(II) complex when compared with a similar bis­(troponato)copper(II) complex. π–π stacking is observed between the tropolone rings, with inter­planar distances of 3.5039 (16) and 3.2933 (15) Å, respectively. Additional stabilisation of the structure is accomplished through C—H...O hydrogen-bonding interactions.

Key indicators

• Single-crystal X-ray study
• T = 100 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.022
• wR factor = 0.066
• Data-to-parameter ratio = 15.7

checkCIF/PLATON results

No syntax errors found



Alert level B
PLAT934_ALERT_3_B Number of (Iobs-Icalc)/SigmaW .gt. 10 Outliers .          1

Alert level C
PLAT232_ALERT_2_C Hirshfeld Test Diff (M-X)  Cu     --  O1      ..       5.01 su
PLAT910_ALERT_3_C Missing # of FCF Reflections Below Th(Min) .....          1

Alert level G
PLAT128_ALERT_4_G Alternate Setting of Space-group P21/c   .......      P21/n
PLAT380_ALERT_4_G Check Incorrectly? Oriented X(sp2)-Methyl Moiety        C18
PLAT380_ALERT_4_G Check Incorrectly? Oriented X(sp2)-Methyl Moiety        C28
PLAT794_ALERT_5_G Note: Tentative Bond Valency for Cu      .......       2.24

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

   0 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
   3 ALERT type 4 Improvement, methodology, query or suggestion
   1 ALERT type 5 Informative message, check

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S1. Comment

Complexes containing tropolonato type derivatives have steadily increased over the last few decades (Roesky, 2000), with most of the work having involved the first and second row transition elements. This attention has been to a large extent due to the medical application of tropolone in radio-pharmaceuticals (Nepveu et al., 1993) and catalyst precursors (Crous et al., 2005; Roodt et al., 2003). Functionalization of the tropolonato backbone (seven-membered ring) has also been investigated with a range of Rh^I and Pd^II complexes reported to date (Steyl et al., 2001; Steyl, 2005).

Heteroatom substitution of the tropolonato moiety has also been reported, most notably the O atoms are replaced with functionalized amino groups, resulting in either the 2- (aminotropone) or 1,2- (aminotropoimine) compounds (Roesky & Burgstein, 1999; Claramunt et al., 2004). Thus, a host of amino and anilino derivatives of tropolone have been reported (Roesky & Burgstein, 1999; Roesky, 2000; Claramunt et al., 2004). The addition of electron-donating or -withdrawing moieties to the N atom can significantly increase the application of these compounds in coordination chemistry. The most interesting observation concerning the Cu^II metal centres in general is the difference in the coordination behaviour of the bidentate-O,O donor atoms compared to the N,N donor atom complexes; the geometrical conformation changes from a square planar (Starikova & Shugam, 1969; Byrn et al., 1993) to a tetrahedral geometry (Park & Marshall, 2005; Dessy & Fares, 1979), respectively. The N-methylaminoacetylacetonato derivative have been reported (Baidina et al., 2004) as a distorted tetrahedral complex.

In an effort to further investigate these types of complexes, the crystal structure of [Cu(TropNMe)₂] is presented.

The copper(II) ion is coordinated by two TropNMe ligands in a square-planar geometry (Fig 1). The Cu²⁺ ion chelates the TropNMe ligand via N1 and O1 to form a five-membered ring. The N1—O1—Cu—N2—O2 moiety is strictly planar. The ligand planes form angles of 6.54 (1)° and 3.12 (1)°, respectively with the 5-membered ring. This compares with literature (Hill & Steyl, 2008). π–π stacking between C11–C17 and C11–C17ⁱ (-x, 1 - y, -z) as well as C11–C17 and C21–C27ⁱⁱ (-x, 2 - y, -z) with intercentroid distances of 4.1483 (4) Å and 3.7827 (4) Å respectively as defined by the seven-membered ring system. Cu—O1 and Cu—O2 bond distances is 1.9313 (2) Å and 1.9386 (2) Å, respectively. This correlates well with literature (Zhang et al., 2008). The Cu—N1 and Cu—N2 bond distances is 1.9276 (2) Å and 1.9291 (2) Å respectively. The O1—Cu—N1 and O2—Cu—N2 angles is 82.292 (4)° and 82.090 (4)° respectively. This correlates well with literature (Kristiansson 2002). The N1—Cu—N2 angle is 175.769 (5)° this is smaller than the O1—Cu—O2 angle, which is 179.229 (6)°. This is in accordance with literature (Liang et al., 2001). The title compound is further stabilized by weak intramolecular C15—H15A···O1 and C16—H16A···O2 hydrogen interactions.

Related literature

For related literature on values of bond lengths and angles, see: Zhang et al. (2008); Hill & Steyl (2008); Kristiansson (2002). For similar structures, see: Liang et al. (2001). For other related structures, see: Starikova & Shugam (1969); Byrn et al. (1993); Park & Marshall (2005); Dessy & Fares (1979); Baidina et al. (2004). For the synthesis of the title compound, see: Roesky & Burgstein (1999); Claramunt et al. (2004). For relativity [Relevance?] and use of the title compound, see: Roesky (2000); Nepveu et al. (1993); Crous et al. (2005); Roodt et al. (2003); Steyl (2005); Steyl et al. (2001).

S2. Experimental

Synthesis of 2-(N-methylamino)tropone (HTropNMe) was done according to the literature procedure (Roesky & Burgstein, 1999; Claramunt et al., 2004), while all other starting materials were obtained from commercially available sources. Cu(NO₃)₂ (100 mg, 0.44 mmol) was dissolved in CHCl₃ or MeOH and refluxed with HTropNMe for 30 min. The product was filtered from the cold solution and dried in air for 24 h. Rhombic dark-green crystals suitable for X-ray diffraction was obtained from a chloroform/ether (1:1, 10 ml) mixture after 2 d. (Yield: 117 mg, 70%) ¹H NMR (300 MHz, CDCl₃, 25°C) 7.32 (m, 2H), 7.12 (d, 1H), 6.95 (d, 1H), 6.81 (t, 1H), 1.56 (s, 3H)

S3. Refinement

All H atoms were positioned geometrically and allowed to ride on their parent atoms, with U_iso(H) = 1.2U_eq(parent) of the parent atom with a C—H distance of 0.93. The methyl H atoms were placed in geometrically idealized positions and constrained to ride on the parent atoms with U_iso(H) = 1.5U_eq(C) and at a distance of 0.96 Å.

Computing details

Data collection: APEX2 (Bruker, 2005); cell refinement: SAINT-Plus (Bruker, 2004); data reduction: SAINT-Plus (Bruker, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenberg & Putz, 2004); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures

Fig. 1. Representation of the title compound, showing the numbering scheme and displacement ellipsoids (50% probability).

Bis[2-(methylamino)troponato]copper(II)

Crystal data

[Cu(C8H8NO)2]	F(000) = 684
Mr = 331.85	Dx = 1.614 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 6754 reflections
a = 6.7541 (9) Å	θ = 2.4–28.2°
b = 9.1599 (12) Å	µ = 1.61 mm^−1
c = 22.084 (3) Å	T = 100 K
β = 92.108 (5)°	Cuboid, black
V = 1365.3 (3) Å^3	0.34 × 0.32 × 0.17 mm
Z = 4

Data collection

Bruker APEXII CCD area-detector diffractometer	2985 independent reflections
Graphite monochromator	2804 reflections with I > 2σ(I)
Detector resolution: 8.5 pixels mm^-1	Rint = 0.032
φ and ω scans	θmax = 27.0°, θmin = 2.4°
Absorption correction: multi-scan (SADABS; Bruker, 2004)	h = −8→8
Tmin = 0.583, Tmax = 0.760	k = −10→11
21665 measured reflections	l = −28→28

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.022	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.066	H-atom parameters constrained
S = 1.06	w = 1/[σ^2(Fo^2) + (0.0363P)^2 + 0.8483P] where P = (Fo^2 + 2Fc^2)/3
2985 reflections	(Δ/σ)max < 0.001
190 parameters	Δρmax = 0.36 e Å^−3
0 restraints	Δρmin = −0.38 e Å^−3

Special details

Experimental. First 80 frames repeated after collection for monitoring possible decay.

Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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
C11	0.0756 (2)	0.73761 (16)	−0.03802 (6)	0.0123 (3)
C12	−0.1170 (2)	0.68077 (16)	−0.01916 (6)	0.0117 (3)
C13	−0.2292 (2)	0.57152 (18)	−0.05113 (7)	0.0152 (3)
H13	−0.3515	0.5479	−0.0336	0.018*
C14	−0.1913 (2)	0.49449 (18)	−0.10280 (7)	0.0172 (3)
H14	−0.2907	0.4259	−0.1147	0.021*
C15	−0.0299 (2)	0.50069 (18)	−0.14071 (7)	0.0171 (3)
H15	−0.0326	0.4366	−0.1746	0.02*
C16	0.1324 (2)	0.59075 (18)	−0.13361 (7)	0.0157 (3)
H16	0.2282	0.5813	−0.1638	0.019*
C17	0.1773 (2)	0.69413 (17)	−0.08858 (7)	0.0141 (3)
H17	0.2993	0.7436	−0.0934	0.017*
C18	−0.3658 (2)	0.70243 (17)	0.05564 (6)	0.0136 (3)
H18A	−0.3873	0.7593	0.0924	0.02*
H18B	−0.364	0.5982	0.0656	0.02*
H18C	−0.4732	0.7221	0.0257	0.02*
C21	−0.0559 (2)	1.02279 (16)	0.17475 (6)	0.0119 (3)
C22	0.1447 (2)	1.06912 (16)	0.15765 (6)	0.0113 (3)
C23	0.2695 (2)	1.16602 (17)	0.19214 (7)	0.0145 (3)
H23	0.3988	1.1773	0.1773	0.017*
C24	0.2340 (2)	1.24600 (17)	0.24341 (7)	0.0172 (3)
H24	0.3422	1.3042	0.2578	0.021*
C25	0.0645 (2)	1.25541 (17)	0.27773 (7)	0.0176 (3)
H25	0.0693	1.3219	0.3108	0.021*
C26	−0.1089 (2)	1.17780 (18)	0.26841 (7)	0.0167 (3)
H26	−0.2094	1.1981	0.2962	0.02*
C27	−0.1587 (2)	1.07348 (18)	0.22402 (7)	0.0146 (3)
H27	−0.2848	1.0296	0.2283	0.018*
C28	0.3903 (2)	1.04390 (17)	0.08191 (7)	0.0136 (3)
H28A	0.4064	0.9896	0.0442	0.02*
H28B	0.4966	1.0171	0.1112	0.02*
H28C	0.3965	1.1489	0.0737	0.02*
N1	−0.17729 (18)	0.74362 (14)	0.03074 (5)	0.0117 (2)
N2	0.19904 (18)	1.00838 (14)	0.10669 (5)	0.0117 (2)
O1	0.15352 (16)	0.83831 (13)	−0.00342 (5)	0.0158 (2)
O2	−0.14060 (15)	0.92738 (13)	0.13907 (5)	0.0142 (2)
Cu	0.00529 (2)	0.881953 (19)	0.067482 (7)	0.01073 (8)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C11	0.0124 (7)	0.0115 (7)	0.0126 (6)	0.0001 (5)	−0.0022 (5)	0.0015 (5)
C12	0.0118 (7)	0.0108 (7)	0.0122 (6)	0.0004 (5)	−0.0013 (5)	0.0018 (5)
C13	0.0146 (7)	0.0149 (8)	0.0161 (7)	−0.0032 (6)	0.0009 (5)	−0.0008 (6)
C14	0.0190 (7)	0.0146 (8)	0.0178 (7)	−0.0037 (6)	−0.0027 (6)	−0.0030 (6)
C15	0.0222 (8)	0.0142 (8)	0.0147 (7)	0.0012 (6)	−0.0007 (6)	−0.0048 (6)
C16	0.0183 (7)	0.0160 (8)	0.0128 (7)	0.0034 (6)	0.0016 (6)	−0.0005 (6)
C17	0.0137 (7)	0.0136 (8)	0.0150 (7)	−0.0007 (6)	0.0004 (5)	0.0005 (5)
C18	0.0122 (7)	0.0146 (8)	0.0142 (7)	−0.0020 (6)	0.0019 (5)	−0.0006 (5)
C21	0.0135 (7)	0.0103 (7)	0.0116 (6)	0.0000 (5)	−0.0024 (5)	0.0028 (5)
C22	0.0120 (7)	0.0094 (7)	0.0123 (6)	0.0013 (5)	−0.0016 (5)	0.0024 (5)
C23	0.0134 (7)	0.0143 (8)	0.0158 (7)	−0.0009 (6)	−0.0013 (5)	0.0000 (6)
C24	0.0210 (8)	0.0134 (8)	0.0166 (7)	−0.0028 (6)	−0.0048 (6)	−0.0014 (6)
C25	0.0274 (8)	0.0133 (8)	0.0120 (7)	−0.0008 (6)	−0.0006 (6)	−0.0026 (5)
C26	0.0224 (8)	0.0162 (8)	0.0118 (7)	0.0015 (6)	0.0030 (6)	0.0001 (6)
C27	0.0160 (7)	0.0150 (8)	0.0128 (7)	−0.0010 (6)	0.0006 (5)	0.0017 (6)
C28	0.0106 (7)	0.0151 (8)	0.0152 (7)	−0.0013 (5)	0.0006 (5)	−0.0007 (5)
N1	0.0115 (6)	0.0115 (6)	0.0122 (6)	−0.0012 (5)	0.0000 (4)	0.0008 (5)
N2	0.0114 (6)	0.0110 (6)	0.0127 (6)	−0.0007 (5)	−0.0011 (4)	−0.0003 (5)
O1	0.0145 (5)	0.0185 (6)	0.0143 (5)	−0.0058 (4)	0.0019 (4)	−0.0048 (4)
O2	0.0137 (5)	0.0167 (6)	0.0123 (5)	−0.0035 (4)	0.0008 (4)	−0.0027 (4)
Cu	0.01051 (11)	0.01176 (12)	0.00990 (11)	−0.00228 (6)	−0.00007 (7)	−0.00182 (6)

Geometric parameters (Å, º)

C11—O1	1.2970 (18)	C21—C22	1.482 (2)
C11—C17	1.390 (2)	C22—N2	1.3196 (19)
C11—C12	1.475 (2)	C22—C23	1.425 (2)
C12—N1	1.3210 (19)	C23—C24	1.377 (2)
C12—C13	1.426 (2)	C23—H23	0.95
C13—C14	1.374 (2)	C24—C25	1.399 (2)
C13—H13	0.95	C24—H24	0.95
C14—C15	1.400 (2)	C25—C26	1.379 (2)
C14—H14	0.95	C25—H25	0.95
C15—C16	1.376 (2)	C26—C27	1.401 (2)
C15—H15	0.95	C26—H26	0.95
C16—C17	1.398 (2)	C27—H27	0.95
C16—H16	0.95	C28—N2	1.4582 (18)
C17—H17	0.95	C28—H28A	0.98
C18—N1	1.4551 (18)	C28—H28B	0.98
C18—H18A	0.98	C28—H28C	0.98
C18—H18B	0.98	N1—Cu	1.9263 (12)
C18—H18C	0.98	N2—Cu	1.9287 (12)
C21—O2	1.2958 (18)	O1—Cu	1.9312 (11)
C21—C27	1.392 (2)	O2—Cu	1.9385 (11)
O1—C11—C17	118.36 (13)	C24—C23—H23	114.6
O1—C11—C12	115.32 (13)	C22—C23—H23	114.6
C17—C11—C12	126.32 (14)	C23—C24—C25	130.46 (15)
N1—C12—C13	122.96 (13)	C23—C24—H24	114.8
N1—C12—C11	112.57 (13)	C25—C24—H24	114.8
C13—C12—C11	124.46 (13)	C26—C25—C24	126.51 (15)
C14—C13—C12	131.26 (14)	C26—C25—H25	116.7
C14—C13—H13	114.4	C24—C25—H25	116.7
C12—C13—H13	114.4	C25—C26—C27	129.55 (15)
C13—C14—C15	130.47 (15)	C25—C26—H26	115.2
C13—C14—H14	114.8	C27—C26—H26	115.2
C15—C14—H14	114.8	C21—C27—C26	131.35 (15)
C16—C15—C14	126.19 (15)	C21—C27—H27	114.3
C16—C15—H15	116.9	C26—C27—H27	114.3
C14—C15—H15	116.9	N2—C28—H28A	109.5
C15—C16—C17	129.65 (15)	N2—C28—H28B	109.5
C15—C16—H16	115.2	H28A—C28—H28B	109.5
C17—C16—H16	115.2	N2—C28—H28C	109.5
C11—C17—C16	131.64 (15)	H28A—C28—H28C	109.5
C11—C17—H17	114.2	H28B—C28—H28C	109.5
C16—C17—H17	114.2	C12—N1—C18	120.21 (12)
N1—C18—H18A	109.5	C12—N1—Cu	115.20 (10)
N1—C18—H18B	109.5	C18—N1—Cu	124.54 (10)
H18A—C18—H18B	109.5	C22—N2—C28	120.26 (12)
N1—C18—H18C	109.5	C22—N2—Cu	115.52 (10)
H18A—C18—H18C	109.5	C28—N2—Cu	124.15 (10)
H18B—C18—H18C	109.5	C11—O1—Cu	114.43 (9)
O2—C21—C27	118.58 (13)	C21—O2—Cu	114.48 (9)
O2—C21—C22	115.20 (13)	N1—Cu—N2	175.77 (5)
C27—C21—C22	126.21 (14)	N1—Cu—O1	82.26 (5)
N2—C22—C23	122.75 (13)	N2—Cu—O1	97.17 (5)
N2—C22—C21	112.46 (13)	N1—Cu—O2	98.51 (5)
C23—C22—C21	124.78 (13)	N2—Cu—O2	82.06 (5)
C24—C23—C22	130.81 (14)	O1—Cu—O2	179.23 (4)
O1—C11—C12—N1	−0.08 (18)	C13—C12—N1—C18	0.0 (2)
C17—C11—C12—N1	−179.70 (14)	C11—C12—N1—C18	179.21 (12)
O1—C11—C12—C13	179.09 (14)	C13—C12—N1—Cu	177.49 (11)
C17—C11—C12—C13	−0.5 (2)	C11—C12—N1—Cu	−3.32 (16)
N1—C12—C13—C14	−179.73 (16)	C23—C22—N2—C28	−2.6 (2)
C11—C12—C13—C14	1.2 (3)	C21—C22—N2—C28	178.48 (12)
C12—C13—C14—C15	−0.7 (3)	C23—C22—N2—Cu	−179.61 (11)
C13—C14—C15—C16	−0.3 (3)	C21—C22—N2—Cu	1.49 (16)
C14—C15—C16—C17	0.5 (3)	C17—C11—O1—Cu	−176.94 (11)
O1—C11—C17—C16	−179.83 (16)	C12—C11—O1—Cu	3.41 (16)
C12—C11—C17—C16	−0.2 (3)	C27—C21—O2—Cu	173.51 (11)
C15—C16—C17—C11	0.1 (3)	C22—C21—O2—Cu	−5.60 (16)
O2—C21—C22—N2	2.74 (18)	C12—N1—Cu—O1	4.09 (10)
C27—C21—C22—N2	−176.28 (14)	C18—N1—Cu—O1	−178.57 (12)
O2—C21—C22—C23	−176.13 (14)	C12—N1—Cu—O2	−175.85 (10)
C27—C21—C22—C23	4.8 (2)	C18—N1—Cu—O2	1.49 (12)
N2—C22—C23—C24	175.20 (16)	C22—N2—Cu—O1	176.53 (11)
C21—C22—C23—C24	−6.0 (3)	C28—N2—Cu—O1	−0.34 (12)
C22—C23—C24—C25	0.7 (3)	C22—N2—Cu—O2	−3.48 (11)
C23—C24—C25—C26	3.1 (3)	C28—N2—Cu—O2	179.66 (12)
C24—C25—C26—C27	0.0 (3)	C11—O1—Cu—N1	−4.09 (10)
O2—C21—C27—C26	−177.74 (16)	C11—O1—Cu—N2	171.68 (10)
C22—C21—C27—C26	1.3 (3)	C21—O2—Cu—N1	−179.20 (10)
C25—C26—C27—C21	−4.0 (3)	C21—O2—Cu—N2	5.04 (10)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C18—H18A···O2	0.98	2.47	3.1222 (18)	124
C28—H28A···O1	0.98	2.41	3.0715 (18)	124