Tetra­kis(μ₃-2-{[1,1-bis­(hydroxy­meth­yl)-2-oxidoeth­yl]imino­meth­yl}phenolato)tetra­copper(II)

In the title tetra­nuclear complex, [Cu₄(C₁₁H₁₃NO₄)₄], which has crystallographic symmetry, the Cu^II ions are coordinated by the tridentate Schiff base ligands, forming a tetra­nuclear Cu₄O₄ cubane-like configuration. The Cu^II ion adopts a CuNO₄ distorted square-pyramidal coordination environment. In the crystal structure, inter­molecular O—H...O bonds help to form a three-dimensional structure.

Key indicators

• Single-crystal X-ray study
• T = 298 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.027
• wR factor = 0.075
• Data-to-parameter ratio = 14.1

checkCIF/PLATON results

No syntax errors found



Alert level B
PLAT601_ALERT_2_B Structure Contains Solvent Accessible VOIDS of .     151.00 A   3 

Alert level C
CELLV02_ALERT_1_C  The supplied cell volume s.u. differs from that
            calculated from the cell parameter s.u.'s by > 2
            Calculated cell volume su =      15.17
            Cell volume su given      =      13.00
PLAT062_ALERT_4_C Rescale T(min) & T(max) by .....................       0.88
PLAT152_ALERT_1_C Supplied and Calc Volume s.u. Inconsistent .....          ?
PLAT790_ALERT_4_C Centre of Gravity not Within Unit Cell: Resd.  #          1
              C44 H52 Cu4 N4 O16

Alert level G
ABSTM02_ALERT_3_G  When printed, the submitted absorption T values will be
            replaced by the scaled T values. Since the ratio of scaled T's
            is identical to the ratio of reported T values, the scaling
            does not imply a change to the absorption corrections used in
            the study.
            Ratio of Tmax expected/reported      0.885
            Tmax scaled      0.431 Tmin scaled      0.405
PLAT794_ALERT_5_G Check Predicted Bond Valency for Cu1         (2)       2.23

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

   2 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
   1 ALERT type 3 Indicator that the structure quality may be low
   2 ALERT type 4 Improvement, methodology, query or suggestion
   1 ALERT type 5 Informative message, check

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S1. Comment

Considerable efforts have been devoted to the study of polynuclear Cu^II complexes due to their importance as models for enzymatic systems (Beinert, 1980) and in studying metal-metal interactions. The chemistry of transition metal complexes of hydroxy(aryl-OH and alkyl-OH) rich molecules containing imine/amine group is important in the biomimetic studies of metalloproteins (Mishtu et al., 2002).

A few structurally characterized multinuclear complexes containing Schiff base ligands has been reported (Mishtu et al., 2002). As part of our ongoing studies (Dong et al., 2007) in this area, we report here the synthesis and crystal structure of the title compound, (I), a tetracopper(II) complex with a tridentate Schiff base ligand derived from the condensation of salicylaldehyde and trihydroxymethylaminomethane. Mishtu et al. (2002) reported the same cluster as a hydrate in a different space group.

Compound (I) contains a teranuclear cubane core based on an approximately cubic array of alternating copper and oxygen atoms (Fig. 1). Each Cu^II atom resides in a distorted square-pyramid coordination environment with one nitrogen and two oxygen atoms from one Schiff base ligand and two oxygen atoms from the neighboring units of the cubane. The Cu atom deviates from the basal plane formed by O1, N1, O2 and O2ⁱ (i = y - 1/4, -x + 5/4, -z + 9/4) by 0.0672 (12) Å, with a significantly longer Cu—O_apical bond distance (Table 1).

Within the cluster, the Cu···Cu distances [3.591 (4) Å, 3.154 (3) Å] are similar to the reported values for related structures (Si et al., 2002; Mishtu et al., 2002), indicating no significant bonding interactions between the Cu^II ions in (I).

In the crystal structure, the intermolecular O—H···O hydrogen bonds help to form a three-dimensional network (Fig. 2, Table 2).

Related literature

For related literature, see: Beinert (1980); Dong et al. (2007); Mishtu et al. (2002); Si et al. (2002).

S2. Experimental

Trihydroxymethylaminomethane (1 mmol, 121.14 mg) was dissolved in hot methanol (10 ml) and added in portions to a methanol solution (3 ml) of salicylaldehyde (1 mmol, 0.11 ml). The mixture was then stirred at 323 K for 2 h. Subsequently, an aqueous solution (2 ml) of cupric acetate hydrate (1 mmol, 199.7 mg) was added dropwise and stirred for another 5 h. The solution was held at room temperature for ten days, whereupon blue blocks of (I) were obtained.

S3. Refinement

All the H atoms were placed in calculated positions (C—H = 0.93–0.97 Å, O—H = 0.82 Å) and refined as riding with U_iso(H) = 1.2U_eq(C) or 1.5U_eq(C_methyl, O).

Computing details

Data collection: SMART (Siemens, 1996); cell refinement: SAINT (Siemens, 1996); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997a); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997a); molecular graphics: SHELXTL (Sheldrick, 1997b); software used to prepare material for publication: SHELXTL.

Figures

	Fig. 1. The structure of (I), showing 30% probability displacement ellipsoids (arbitrary spheres for the H atoms). The asymmetric atoms are labelled.
	Fig. 2. Packing diagram of (I) with hydrogen bonds shown as dashed lines.

Tetrakis(µ₃-2-{[1,1-bis(hydroxymethyl)-2-οxidoethyl]iminomethyl}phenolato)tetracopper(II)

Crystal data

[Cu4(C11H13NO4)4]	Dx = 1.528 Mg m^−3
Mr = 1147.06	Mo Kα radiation, λ = 0.71073 Å
Tetragonal, I41/a	Cell parameters from 5431 reflections
Hall symbol: -I 4ad	θ = 2.4–28.1°
a = 17.209 (3) Å	µ = 1.75 mm^−1
c = 16.836 (3) Å	T = 298 K
V = 4986.0 (13) Å^3	Block, blue
Z = 4	0.53 × 0.49 × 0.48 mm
F(000) = 2352

Data collection

Siemens SMART CCD area-detector diffractometer	2203 independent reflections
Radiation source: fine-focus sealed tube	1821 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.050
ω scans	θmax = 25.0°, θmin = 1.7°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −20→18
Tmin = 0.457, Tmax = 0.487	k = −20→16
12748 measured reflections	l = −18→20

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)] = 0.028	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.075	H-atom parameters constrained
S = 1.06	w = 1/[σ^2(Fo^2) + (0.0407P)^2 + 3.0697P] where P = (Fo^2 + 2Fc^2)/3
2203 reflections	(Δ/σ)max = 0.002
156 parameters	Δρmax = 0.32 e Å^−3
0 restraints	Δρmin = −0.19 e Å^−3

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
Cu1	0.396178 (15)	0.739558 (15)	1.069439 (16)	0.02320 (12)
N1	0.37415 (11)	0.69497 (11)	0.96723 (11)	0.0261 (4)
O1	0.31430 (10)	0.81400 (10)	1.06436 (10)	0.0347 (4)
O2	0.48427 (9)	0.66875 (9)	1.07064 (8)	0.0235 (4)
O3	0.36321 (12)	0.57702 (11)	0.82462 (11)	0.0452 (5)
H3	0.3518	0.5309	0.8286	0.068*
O4	0.32782 (10)	0.58053 (12)	1.07332 (10)	0.0393 (5)
H4	0.3644	0.5761	1.1042	0.059*
C1	0.32492 (15)	0.72192 (14)	0.91698 (15)	0.0341 (6)
H1	0.3192	0.6951	0.8694	0.041*
C2	0.27757 (15)	0.79070 (15)	0.92818 (15)	0.0343 (6)
C3	0.27275 (14)	0.83153 (14)	1.00084 (15)	0.0293 (5)
C4	0.22008 (15)	0.89372 (15)	1.00520 (17)	0.0400 (7)
H4A	0.2151	0.9208	1.0527	0.048*
C5	0.17574 (18)	0.91569 (17)	0.94118 (18)	0.0492 (8)
H5A	0.1420	0.9577	0.9459	0.059*
C6	0.18063 (19)	0.87623 (18)	0.87002 (19)	0.0543 (9)
H6	0.1508	0.8914	0.8267	0.065*
C7	0.23011 (18)	0.81440 (18)	0.86439 (17)	0.0497 (8)
H7	0.2326	0.7870	0.8168	0.060*
C8	0.40970 (14)	0.61676 (13)	0.95857 (14)	0.0262 (5)
C9	0.48709 (13)	0.61901 (14)	1.00416 (14)	0.0285 (5)
H9A	0.5000	0.5669	1.0217	0.034*
H9B	0.5279	0.6364	0.9686	0.034*
C10	0.42851 (15)	0.59321 (15)	0.87300 (15)	0.0355 (6)
H10A	0.4581	0.6347	0.8484	0.043*
H10B	0.4614	0.5475	0.8743	0.043*
C11	0.35195 (14)	0.55883 (15)	0.99569 (15)	0.0328 (6)
H11A	0.3066	0.5549	0.9617	0.039*
H11B	0.3761	0.5079	0.9980	0.039*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cu1	0.02486 (18)	0.02156 (18)	0.02318 (18)	0.00370 (11)	−0.00404 (12)	−0.00364 (11)
N1	0.0298 (11)	0.0224 (10)	0.0260 (10)	0.0035 (8)	−0.0045 (9)	−0.0034 (8)
O1	0.0382 (10)	0.0368 (10)	0.0291 (9)	0.0146 (8)	−0.0113 (8)	−0.0098 (8)
O2	0.0288 (9)	0.0195 (8)	0.0222 (9)	0.0043 (6)	−0.0045 (7)	−0.0024 (6)
O3	0.0653 (14)	0.0341 (11)	0.0362 (10)	0.0008 (9)	−0.0197 (10)	−0.0073 (9)
O4	0.0288 (10)	0.0581 (12)	0.0310 (10)	0.0011 (9)	0.0001 (8)	0.0036 (9)
C1	0.0433 (16)	0.0315 (14)	0.0273 (13)	0.0041 (12)	−0.0095 (12)	−0.0054 (11)
C2	0.0384 (15)	0.0309 (14)	0.0336 (14)	0.0049 (11)	−0.0102 (12)	0.0015 (11)
C3	0.0303 (14)	0.0229 (12)	0.0346 (14)	0.0016 (10)	−0.0066 (11)	0.0009 (11)
C4	0.0381 (16)	0.0364 (15)	0.0456 (16)	0.0106 (12)	−0.0080 (13)	−0.0057 (13)
C5	0.0496 (18)	0.0366 (16)	0.061 (2)	0.0180 (13)	−0.0146 (15)	0.0033 (14)
C6	0.061 (2)	0.0534 (19)	0.0489 (19)	0.0191 (16)	−0.0243 (15)	0.0073 (15)
C7	0.064 (2)	0.0486 (18)	0.0360 (16)	0.0164 (15)	−0.0187 (14)	−0.0041 (14)
C8	0.0288 (13)	0.0239 (12)	0.0258 (12)	0.0027 (10)	−0.0032 (10)	−0.0069 (10)
C9	0.0254 (13)	0.0289 (13)	0.0312 (14)	0.0042 (10)	−0.0018 (11)	−0.0075 (11)
C10	0.0441 (16)	0.0339 (15)	0.0287 (14)	0.0027 (12)	−0.0008 (12)	−0.0082 (11)
C11	0.0323 (14)	0.0298 (14)	0.0364 (15)	0.0016 (10)	−0.0008 (11)	−0.0002 (11)

Geometric parameters (Å, º)

Cu1—O1	1.9063 (16)	C3—C4	1.404 (3)
Cu1—N1	1.9218 (19)	C4—C5	1.374 (4)
Cu1—O2^i	1.9438 (15)	C4—H4A	0.9300
Cu1—O2	1.9451 (16)	C5—C6	1.380 (4)
Cu1—O2^ii	2.5930 (16)	C5—H5A	0.9300
N1—C1	1.284 (3)	C6—C7	1.366 (4)
N1—C8	1.486 (3)	C6—H6	0.9300
O1—C3	1.321 (3)	C7—H7	0.9300
O2—C9	1.410 (3)	C8—C10	1.531 (3)
O2—Cu1^iii	1.9438 (15)	C8—C9	1.538 (3)
O3—C10	1.416 (3)	C8—C11	1.540 (3)
O3—H3	0.8200	C9—H9A	0.9700
O4—C11	1.421 (3)	C9—H9B	0.9700
O4—H4	0.8200	C10—H10A	0.9700
C1—C2	1.449 (3)	C10—H10B	0.9700
C1—H1	0.9300	C11—H11A	0.9700
C2—C7	1.410 (4)	C11—H11B	0.9700
C2—C3	1.413 (3)
O1—Cu1—N1	94.72 (7)	C6—C5—H5A	119.6
O1—Cu1—O2^i	91.99 (7)	C7—C6—C5	118.8 (3)
N1—Cu1—O2^i	169.85 (7)	C7—C6—H6	120.6
O1—Cu1—O2	176.00 (7)	C5—C6—H6	120.6
N1—Cu1—O2	85.00 (7)	C6—C7—C2	122.3 (3)
O2^i—Cu1—O2	88.83 (7)	C6—C7—H7	118.9
N1—Cu1—O2^ii	113.99 (7)	C2—C7—H7	118.9
O2^i—Cu1—O2^ii	72.12 (6)	N1—C8—C10	114.8 (2)
O2—Cu1—O2^ii	76.28 (6)	N1—C8—C9	106.55 (18)
C1—N1—C8	122.3 (2)	C10—C8—C9	107.05 (19)
C1—N1—Cu1	125.16 (17)	N1—C8—C11	106.31 (19)
C8—N1—Cu1	111.62 (14)	C10—C8—C11	110.29 (19)
C3—O1—Cu1	126.14 (15)	C9—C8—C11	111.9 (2)
C9—O2—Cu1^iii	128.79 (14)	O2—C9—C8	112.44 (18)
C9—O2—Cu1	113.51 (13)	O2—C9—H9A	109.1
Cu1^iii—O2—Cu1	108.40 (7)	C8—C9—H9A	109.1
C10—O3—H3	109.5	O2—C9—H9B	109.1
C11—O4—H4	109.5	C8—C9—H9B	109.1
N1—C1—C2	125.5 (2)	H9A—C9—H9B	107.8
N1—C1—H1	117.3	O3—C10—C8	115.2 (2)
C2—C1—H1	117.3	O3—C10—H10A	108.5
C7—C2—C3	118.8 (2)	C8—C10—H10A	108.5
C7—C2—C1	117.6 (2)	O3—C10—H10B	108.5
C3—C2—C1	123.5 (2)	C8—C10—H10B	108.5
O1—C3—C4	118.7 (2)	H10A—C10—H10B	107.5
O1—C3—C2	123.7 (2)	O4—C11—C8	113.1 (2)
C4—C3—C2	117.5 (2)	O4—C11—H11A	109.0
C5—C4—C3	121.8 (3)	C8—C11—H11A	109.0
C5—C4—H4A	119.1	O4—C11—H11B	109.0
C3—C4—H4A	119.1	C8—C11—H11B	109.0
C4—C5—C6	120.8 (3)	H11A—C11—H11B	107.8
C4—C5—H5A	119.6
N1—Cu1—O2—O1	86.3 (9)

Symmetry codes: (i) y−1/4, −x+5/4, −z+9/4; (ii) −x+1, −y+3/2, z; (iii) −y+5/4, x+1/4, −z+9/4.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O3—H3···O4^iv	0.82	1.91	2.723 (3)	172
O4—H4···O1^iii	0.82	1.85	2.668 (2)	171

Symmetry codes: (iii) −y+5/4, x+1/4, −z+9/4; (iv) y−1/4, −x+3/4, z−1/4.