Aqua­tris­(1,10-phenan­throline)­(trans-2,3-di­methyl­acrylato)­ytterbium(III)

The title mononuclear complex, [Yb(C₅H₇O₂)₃(C₁₂H₈N₂)(H₂O)], is a most uncommon carboxylate complex of a rare earth metal. Each Yb^III ion is eightfold coordinated, being bonded to five O atoms of three dimethylacrylate groups, both N atoms of a phenanthroline and one O atom of a water molecule, giving a distorted square antiprismatic coordination polyhedron.

S1. Comment

The chemistry of rare earth complexes is a fascinating field because of the potential use of such complexes as extraction agents, luminescent compounds and catalysts (Richardon, 1982; Molander & Hoberg, 1992). Knowledge of the structures of lanthanide compounds is vital to the interpretation of their bonding and chemical properties. trans-2,3-dimethylacrylic acid is a prochiral compound and has often been used as model substrate in asymmetric hydrogenation catalysis (Ashby & Halpern, 1991). Information on the stereochemistry of its complexes can help to clarify the catalytic mechanism of asymmetric homogeneous hydrogenation. The present investigation of the title compound, (I), forms part of our studies of rare earth complexes with unsaturated carboxylic acids.

In (I), the Yb^III ion is eightfold coordinated by five O atoms from three trans-2,3-dimethylacrylato groups, two N atoms from a phenanthroline and one O atom from a water molecule. The phenanthroline forms a five-membered chelate ring (consisting of Yb, N1, N2, C11 and C12) and two trans-2,3-dimethylacrylato groups act as bidentate chelating ligands, forming two four-membered chelating rings (consisting of Yb, O3, C18 and O4, and of Yb, O5, C23 and O6). The two four-atom mean planes make a dihedral angle of 93.8 (2)° and form dihedral angles with mean plane through Yb, N1, C11, C12 and N2 of 100.8 (2) and 8.1 (2)°, respectively. The coordination polyhedron of Yb^III is a slightly distorted square antiprism. The two N atoms of a phenanthroline group and five carboxylato O atoms and the O atom from a water molecule occupy the ligand sites of two square faces of the antiprism. The least-squares planes through O3, O4, O5 and O6, and O1, O7, N1 and N2 are essentially parallel to each other [dihedral angle about 3.4 (2)°] and the distance of Yb^III from the least-squares mean planes of the square faces are 1.3998 (6) and 1.2324 Å, respectively.

Lanthanide carboxylate complexes have been widely studied and most are found to exhibit a variety of dimeric, trimeric or infinite chain structures in the solid state (Ma & Ni, 1996; Wei, 1998). The title complex, however, is a monomer. We beleive that two factors hinder the complex polymerization. One is the small radius of Yb^III (a consequence of lanthanide contraction). The other is steric hindrance: the trans-2,3-dimethylacrylato group is larger than the methylacrylato ligand in the dimeric complex [Yb(C₄H₅O₂)₃(C₁₂H₈N₂)]₂, (II) (Lu et al., 1999).

Carboxylate ligands exhibit various modes of coordination to rare earth metal ions (Ma & Ni, 1996). The title complex presents two modes, bidentate or unidentate, and also has two distinct Yb—O distances. The average Yb—O_chelating bond length (2.348 Å) in the title complex is nearly equal to the corresponding length (2.363 Å) in complex (II). It indicates that different carboxylato groups with the same mode of coordination with Yb^III ion have essentially the same bond lengths. The distances Yb—O_unidentate and Yb—O_water are 2.233 (8) and 2.295 (7) Å, respectively, which are slightly larger than average value (2.218 Å) of the Yb—O_bridging bonds in complex (II). The Yb—N bond lengths are similar at 2.458 (8) and 2.478 (9) Å. The Yb—O_chelating bond lengths are significantly longer than the sum of the covalent radii of the two atoms, which is to be expected because the angles O3—Yb—O4 and O5—Yb—O6 of about 55° indicate ring strain. This may be the reason why a water molecule also takes part in the coordination. The water ligand also forms an intramolecular hydrogen bond with the uncoordinated O atom of a carboxylate ligand.

The carboxyl groups give rise to very strong IR absorptions, which can in principle be used to distinguish between the different coordination modes of the ligands (i.e. ionic, unidentate or bidentate) by comparison of the band separation with that of the corresponding sodium compound (Deacon & Phillips, 1980). Separation between ν_asym(COO) and ν_sym(COO), which are substantially greater than the value of 170 cm^-1 for the sodium salt, are thought to be indicative of unidentate coordination. However, the value for the title complex, in which the carboxylate ligands are bidentate and unidentate, is 150 cm^-1, indicating that the spectroscopic technique could not correctly identify the coordination mode.

S2. Experimental

trans-2,3-Dimethylacrylic acid (150 mg,1.5 mmol) and Yb(NO₃)₃·6H₂O (130 mg, 0.3 mmol) were dissolved in of aqueous ethanol (12 ml, 1:1 v/v) and adjusted to pH 4.3 by the addition of 10% NaOH solution. An ethanolic solution of 1,10-phenanthroline (60 mg, 0.3 mmol) was added, with stirring, to the solution. After filtration, the filtrate was allowed to stand at room temperature, whereupon single crystals suitable for X-ray work were obtained after a few days. Analysis: calculated C 48.50, H 4.67, N 4.19, Yb 25.88%; found C 49.06, H 4.91, N 4.13, Yb 26.08%. IR spectra: ν_as (COO) 1578, ν_s (COO) 1428, ν (C═C) 1658, ν (C— C, phen ring) 1520, ν (C—H, out of phen ring bend) 731 and 850 cm^-1.

Computing details

Data collection: MSC/AFC Diffractometer Control Software (Molecular Structure Coprporation, 1988); cell refinement: MSC/AFC Diffractometer Control Software; data reduction: TEXSAN (Molecular Structure Coprporation, 1985); program(s) used to solve structure: DIRDIF92 (Beurskens et al., 1992), SHELXS86 (Sheldrick, 1985); program(s) used to refine structure: TEXSAN; software used to prepare material for publication: TEXSAN.

Figures

Fig. 1. The molecular structure and atom-numbering scheme of the title complex. Displacement ellipsoids are shown at the 40% probability level and H atoms are omitted for clarity.

Aquatris(trans-2,3-dimethylacrylato)(1,10-phenanthroline)ytterbium(III)

Crystal data

[Yb(C5H7O2)3(C12H8N2)(H2O)]	F(000) = 1332.00
Mr = 668.59	Dx = 1.606 Mg m^−3 Dm = 1.64 Mg m^−3 Dm measured by ?
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71069 Å
a = 9.512 (3) Å	Cell parameters from 21 reflections
b = 20.472 (10) Å	θ = 13.9–25.2°
c = 14.412 (3) Å	µ = 3.43 mm^−1
β = 99.92 (2)°	T = 293 K
V = 2764 (1) Å^3	Square prism, colourless
Z = 4	0.30 × 0.20 × 0.20 mm

Data collection

AFC-7R four-circle diffractometer	Rint = 0.053
ω/2θ scans	θmax = 25.5°
Absorption correction: part of the refinement model (ΔF) (Walker & Stuart, 1983)	h = 0→11
Tmin = 0.377, Tmax = 0.504	k = 0→24
5655 measured reflections	l = −17→17
5384 independent reflections	3 standard reflections every 200 reflections
3359 reflections with I > 2.5σ(I)	intensity decay: 5.7%

Refinement

Refinement on F	w = 1/σ^2(Fo) + 4(Fo)^2/σ^2(Fo)^2 w = 1/σ^2(Fo) + 4(Fo)^2/σ^2(Fo)^2
R[F^2 > 2σ(F^2)] = 0.052	(Δ/σ)max = 0.05
wR(F^2) = 0.063	Δρmax = 1.08 e Å^−3
S = 1.98	Δρmin = −1.21 e Å^−3
3359 reflections	Extinction correction: Secondary extinction (Zachariasen, 1963)
335 parameters	Extinction coefficient: 1.69042 × 10^-7
H-atom parameters not refined

Special details

Refinement. The data were corrected for Lorentz and polarization effects, and a secondary extinction correction was applied. The structure was solved by heavy-atom Patterson methods (Sheldrick, 1985) and expanded using Fourier techniques (Beurskens et al., 1992). All non-H atoms were refined by full-matrix least-squares methods with anisotropic displacement parameters, and H atoms were located in ΔF maps but not refined.

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

	x	y	z	Uiso*/Ueq
Yb	0.02508 (5)	0.03570 (2)	0.20685 (3)	0.0443
O1	0.109 (1)	0.1360 (4)	0.2433 (5)	0.0661
O2	0.105 (1)	0.2016 (4)	0.1216 (6)	0.0976
O3	−0.0629 (9)	−0.0626 (4)	0.2581 (5)	0.0595
O4	−0.0824 (9)	−0.0501 (4)	0.1058 (5)	0.0518
O5	0.2309 (9)	−0.0117 (5)	0.1733 (5)	0.0673
O6	0.2201 (8)	0.0061 (4)	0.3216 (5)	0.0591
O7	0.0138 (9)	0.0843 (4)	0.0622 (5)	0.0582
N1	−0.0713 (10)	0.0675 (4)	0.3480 (5)	0.0431
N2	−0.2295 (10)	0.0687 (5)	0.1737 (6)	0.0507
C1	0.007 (1)	0.0693 (6)	0.4317 (8)	0.0543
C2	−0.045 (2)	0.0883 (7)	0.5129 (8)	0.0664
C3	−0.182 (2)	0.1064 (7)	0.5055 (8)	0.0639
C4	−0.270 (1)	0.1076 (6)	0.4149 (7)	0.0523
C5	−0.415 (2)	0.1274 (7)	0.4010 (9)	0.0719
C6	−0.495 (1)	0.1276 (7)	0.316 (1)	0.0746
C7	−0.437 (1)	0.1064 (7)	0.2358 (8)	0.0592
C8	−0.515 (1)	0.1039 (7)	0.1443 (10)	0.0736
C9	−0.450 (1)	0.0841 (8)	0.0720 (9)	0.0749
C10	−0.309 (1)	0.0667 (7)	0.0888 (9)	0.0651
C11	−0.293 (1)	0.0874 (5)	0.2472 (7)	0.0443
C12	−0.207 (1)	0.0877 (5)	0.3405 (7)	0.0438
C13	0.131 (1)	0.1897 (6)	0.2058 (8)	0.0586
C14	0.202 (1)	0.2424 (6)	0.2736 (8)	0.0561
C15	0.213 (2)	0.2339 (7)	0.362 (1)	0.0782
C16	0.277 (2)	0.2808 (9)	0.441 (1)	0.1256
C17	0.250 (2)	0.3002 (8)	0.225 (1)	0.1111
C18	−0.101 (1)	−0.0842 (6)	0.1765 (8)	0.0482
C19	−0.174 (1)	−0.1501 (6)	0.1635 (8)	0.0528
C20	−0.241 (2)	−0.1657 (7)	0.0749 (9)	0.0718
C21	−0.324 (2)	−0.224 (1)	0.048 (1)	0.1325
C22	−0.175 (2)	−0.1913 (8)	0.2456 (9)	0.0895
C23	0.287 (1)	−0.0153 (6)	0.2606 (8)	0.0516
C24	0.432 (1)	−0.0450 (7)	0.2876 (9)	0.0638
C25	0.492 (1)	−0.0443 (6)	0.3765 (8)	0.0599
C26	0.635 (2)	−0.0717 (8)	0.414 (1)	0.0851
C27	0.497 (1)	−0.0728 (8)	0.2082 (10)	0.0817
H1	0.1202	0.0505	0.4393	0.0858
H2	0.0168	0.0886	0.5722	0.0784
H3	−0.2202	0.1183	0.5600	0.0858
H4	−0.4569	0.1406	0.4536	0.0830
H5	−0.5913	0.1419	0.3079	0.0858
H6	−0.6129	0.1163	0.1319	0.0858
H7	−0.5011	0.0828	0.0093	0.0866
H8	−0.2651	0.0521	0.0381	0.0821
H9	0.1765	0.1941	0.3820	0.0766
H10	0.2703	0.2617	0.5000	0.1552
H11	0.2255	0.3206	0.4339	0.1552
H12	0.3740	0.2885	0.4370	0.1552
H13	0.2008	0.3379	0.2400	0.0766
H14	0.3499	0.3062	0.2442	0.1224
H15	0.2304	0.2934	0.1584	0.1224
H16	−0.2314	−0.1349	0.0265	0.0883
H17	−0.3561	−0.2226	−0.0187	0.1513
H18	−0.2637	−0.2609	0.0626	0.1224
H19	−0.4011	−0.2254	0.0797	0.1513
H20	−0.1326	−0.2317	0.2360	0.1047
H21	−0.2707	−0.1974	0.2542	0.1047
H22	−0.1226	−0.1701	0.2993	0.1047
H23	0.4669	−0.0335	0.4533	0.0858
H24	0.6246	−0.1133	0.4406	0.0858
H25	0.6877	−0.0759	0.3636	0.1011
H26	0.6843	−0.0432	0.4602	0.1011
H27	0.5110	−0.0387	0.1663	0.1011
H28	0.4358	−0.1050	0.1762	0.0959
H29	0.5869	−0.0920	0.2334	0.0858
H30	0.0586	0.1262	0.0569	0.0709
H31	−0.0353	0.0643	0.0065	0.1333

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Yb	0.0529 (3)	0.0495 (3)	0.0323 (3)	0.0037 (3)	0.0124 (2)	−0.0023 (3)
O1	0.105 (7)	0.048 (5)	0.045 (5)	−0.011 (5)	0.013 (5)	−0.001 (4)
O2	0.18 (1)	0.063 (6)	0.049 (5)	−0.017 (7)	0.031 (7)	0.001 (5)
O3	0.081 (6)	0.056 (5)	0.040 (4)	−0.013 (5)	0.009 (4)	−0.006 (4)
O4	0.075 (5)	0.048 (5)	0.034 (4)	−0.003 (4)	0.015 (4)	−0.010 (3)
O5	0.059 (5)	0.100 (7)	0.046 (5)	0.020 (5)	0.016 (4)	−0.013 (5)
O6	0.053 (5)	0.082 (6)	0.042 (4)	0.017 (5)	0.007 (4)	−0.008 (4)
O7	0.080 (6)	0.065 (5)	0.031 (4)	0.000 (5)	0.013 (4)	0.006 (4)
N1	0.059 (6)	0.044 (5)	0.027 (4)	0.007 (5)	0.008 (4)	0.008 (4)
N2	0.057 (6)	0.055 (6)	0.040 (5)	0.006 (5)	0.007 (4)	−0.008 (5)
C1	0.065 (8)	0.056 (7)	0.044 (7)	0.012 (7)	0.015 (6)	0.006 (6)
C2	0.087 (10)	0.077 (10)	0.038 (6)	0.001 (8)	0.018 (6)	−0.009 (6)
C3	0.091 (10)	0.065 (8)	0.039 (6)	0.002 (8)	0.023 (7)	−0.007 (6)
C4	0.061 (7)	0.053 (7)	0.044 (6)	0.006 (6)	0.014 (6)	−0.004 (6)
C5	0.09 (1)	0.08 (1)	0.054 (8)	0.011 (8)	0.028 (8)	−0.010 (7)
C6	0.077 (10)	0.08 (1)	0.075 (10)	0.018 (8)	0.030 (8)	−0.001 (8)
C7	0.063 (8)	0.066 (8)	0.049 (7)	0.005 (7)	0.010 (6)	−0.003 (6)
C8	0.055 (8)	0.09 (1)	0.078 (9)	0.012 (8)	0.010 (7)	0.013 (9)
C9	0.064 (8)	0.11 (1)	0.049 (7)	0.015 (8)	0.000 (6)	−0.004 (8)
C10	0.073 (9)	0.072 (9)	0.053 (8)	0.002 (8)	0.017 (7)	−0.005 (7)
C11	0.050 (6)	0.044 (7)	0.042 (6)	0.001 (5)	0.017 (5)	0.001 (5)
C12	0.062 (7)	0.033 (6)	0.039 (6)	0.008 (5)	0.017 (5)	0.006 (5)
C13	0.085 (9)	0.054 (8)	0.041 (6)	0.002 (7)	0.022 (6)	0.000 (6)
C14	0.072 (8)	0.042 (7)	0.056 (8)	0.009 (6)	0.016 (7)	0.004 (6)
C15	0.10 (1)	0.061 (9)	0.073 (10)	−0.014 (8)	0.012 (9)	−0.024 (8)
C16	0.15 (2)	0.10 (1)	0.11 (1)	−0.01 (1)	−0.03 (1)	−0.03 (1)
C17	0.15 (2)	0.07 (1)	0.13 (1)	−0.03 (1)	0.06 (1)	−0.01 (1)
C18	0.058 (7)	0.049 (7)	0.040 (6)	0.000 (6)	0.013 (5)	−0.012 (6)
C19	0.059 (7)	0.052 (7)	0.052 (7)	0.012 (6)	0.020 (6)	0.000 (6)
C20	0.080 (9)	0.08 (1)	0.057 (8)	−0.028 (8)	0.010 (7)	−0.016 (7)
C21	0.15 (2)	0.12 (2)	0.13 (2)	0.00 (1)	0.01 (1)	−0.02 (1)
C22	0.12 (1)	0.09 (1)	0.052 (8)	−0.01 (1)	−0.003 (8)	0.014 (8)
C23	0.065 (7)	0.054 (8)	0.036 (6)	0.004 (6)	0.008 (6)	0.001 (5)
C24	0.059 (7)	0.074 (9)	0.062 (8)	0.008 (7)	0.020 (6)	0.006 (7)
C25	0.063 (7)	0.069 (9)	0.044 (7)	0.011 (7)	−0.002 (6)	0.009 (6)
C26	0.072 (9)	0.11 (1)	0.073 (9)	0.026 (9)	0.007 (8)	0.003 (9)
C27	0.066 (9)	0.10 (1)	0.08 (1)	0.032 (8)	0.028 (8)	0.005 (9)

Geometric parameters (Å, º)

Yb—O1	2.233 (8)	C4—C5	1.42 (2)
Yb—O3	2.347 (8)	C4—C12	1.38 (1)
Yb—O4	2.396 (7)	C5—C6	1.32 (2)
Yb—O5	2.310 (8)	C6—C7	1.43 (2)
Yb—O6	2.342 (7)	C7—C8	1.40 (2)
Yb—O7	2.295 (7)	C7—C11	1.40 (2)
Yb—N1	2.458 (8)	C8—C9	1.37 (2)
Yb—N2	2.480 (9)	C9—C10	1.36 (2)
O1—C13	1.26 (1)	C11—C12	1.45 (1)
O2—C13	1.22 (1)	C13—C14	1.53 (2)
O3—C18	1.25 (1)	C14—C15	1.28 (2)
O4—C18	1.27 (1)	C14—C17	1.49 (2)
O5—C23	1.28 (1)	C15—C16	1.53 (2)
O6—C23	1.25 (1)	C18—C19	1.51 (2)
N1—C1	1.30 (1)	C19—C20	1.36 (2)
N1—C12	1.34 (1)	C19—C22	1.45 (2)
N2—C10	1.32 (1)	C20—C21	1.45 (2)
N2—C11	1.36 (1)	C23—C24	1.50 (2)
C1—C2	1.40 (2)	C24—C25	1.31 (2)
C2—C3	1.35 (2)	C24—C27	1.51 (2)
C3—C4	1.43 (2)	C25—C26	1.49 (2)
O1—Yb—O3	147.9 (3)	C1—C2—C3	119 (1)
O1—Yb—O4	156.3 (3)	C2—C3—C4	119 (1)
O1—Yb—O5	98.9 (3)	C3—C4—C5	122 (1)
O1—Yb—O6	82.2 (3)	C3—C4—C12	116 (1)
O1—Yb—O7	76.9 (3)	C5—C4—C12	121 (1)
O1—Yb—N1	74.4 (3)	C4—C5—C6	121 (1)
O1—Yb—N2	95.3 (3)	C5—C6—C7	120 (1)
O3—Yb—O4	54.9 (2)	C6—C7—C8	123 (1)
O3—Yb—O5	93.8 (3)	C6—C7—C11	119 (1)
O3—Yb—O6	80.7 (3)	C8—C7—C11	116 (1)
O3—Yb—O7	133.9 (3)	C7—C8—C9	119 (1)
O3—Yb—N1	76.3 (3)	C8—C9—C10	120 (1)
O3—Yb—N2	84.6 (3)	N2—C10—C9	122 (1)
O4—Yb—O5	81.5 (3)	N2—C11—C7	122 (1)
O4—Yb—O6	116.3 (3)	N2—C11—C12	117.9 (10)
O4—Yb—O7	79.5 (3)	C7—C11—C12	119.4 (10)
O4—Yb—N1	121.1 (3)	N1—C12—C4	124 (1)
O4—Yb—N2	77.4 (3)	N1—C12—C11	117.0 (9)
O5—Yb—O6	56.1 (3)	C4—C12—C11	118 (1)
O5—Yb—O7	84.3 (3)	O1—C13—O2	125 (1)
O5—Yb—N1	137.3 (3)	O1—C13—C14	115 (1)
O5—Yb—N2	155.4 (3)	O2—C13—C14	119 (1)
O6—Yb—O7	131.4 (3)	C13—C14—C15	119 (1)
O6—Yb—N1	81.2 (3)	C13—C14—C17	113 (1)
O6—Yb—N2	146.6 (3)	C15—C14—C17	127 (1)
O7—Yb—N1	132.1 (3)	C14—C15—C16	127 (1)
O7—Yb—N2	79.4 (3)	O3—C18—O4	119 (1)
N1—Yb—N2	66.2 (3)	O3—C18—C19	119 (1)
Yb—O1—C13	141.4 (8)	O4—C18—C19	121.0 (9)
Yb—O3—C18	94.0 (7)	C18—C19—C20	117 (1)
Yb—O4—C18	91.2 (6)	C18—C19—C22	118 (1)
Yb—O5—C23	92.3 (7)	C20—C19—C22	124 (1)
Yb—O6—C23	91.7 (7)	C19—C20—C21	126 (1)
Yb—N1—C1	122.6 (8)	O5—C23—O6	119 (1)
Yb—N1—C12	120.4 (6)	O5—C23—C24	119 (1)
C1—N1—C12	116.9 (9)	O6—C23—C24	121 (1)
Yb—N2—C10	123.6 (8)	C23—C24—C25	118 (1)
Yb—N2—C11	118.5 (7)	C23—C24—C27	116 (1)
C10—N2—C11	117 (1)	C25—C24—C27	125 (1)
N1—C1—C2	123 (1)	C24—C25—C26	124 (1)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O7—H30···O2	0.97	1.82	2.650 (12)	141.6