Tris(N-acetyl­glycinato-κ²O,O′)triaquasamarium(III)

The title complex, [Sm(C₄H₆NO₃)₃(H₂O)₃], was prepared by reacting samarium(III) carbonate with N-acetyl­glycine in an aqueous medium. The Sm^III atom is coordinated by nine O atoms, six of them belonging to the three carboxyl­ate groups of the ligands and three to the water mol­ecules. The coordination geometry can be described in terms of a 4,4,4-tricapped triangular prism. The mol­ecule lies on a threefold rotation axis.

Key indicators

• Single-crystal X-ray study
• T = 298 K
• Mean [sigma](C-C) = 0.009 Å
• R factor = 0.020
• wR factor = 0.051
• Data-to-parameter ratio = 8.4

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT062_ALERT_4_C Rescale T(min) & T(max) by .....................       0.93
PLAT164_ALERT_4_C Nr. of Refined C-H H-Atoms in Heavy-At Struct...          2
PLAT180_ALERT_3_C Check Cell Rounding: # of Values Ending with 0 =          3
PLAT222_ALERT_3_C Large Non-Solvent    H     Ueq(max)/Ueq(min) ...       3.79 Ratio
PLAT342_ALERT_3_C Low Bond Precision on C-C Bonds (x 1000) Ang ...         10
PLAT764_ALERT_4_C Overcomplete CIF Bond List Detected (Rep/Expd) .       1.19 Ratio

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      0.931
            Tmax scaled      0.531 Tmin scaled      0.339
REFLT03_ALERT_4_G  WARNING: Large fraction of Friedel related reflns may
                     be needed to determine absolute structure
           From the CIF: _diffrn_reflns_theta_max           27.51
           From the CIF: _reflns_number_total                900
           Count of symmetry unique reflns          725
           Completeness (_total/calc)            124.14%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured       175
           Fraction of Friedel pairs measured     0.241
           Are heavy atom types Z>Si present        yes
PLAT794_ALERT_5_G Check Predicted Bond Valency for Sm1         (3)       3.14
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......          3

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   6 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
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   5 ALERT type 3 Indicator that the structure quality may be low
   4 ALERT type 4 Improvement, methodology, query or suggestion
   1 ALERT type 5 Informative message, check

---

S1. Comment

Rare earth complexes of N-acetylglycine were synthesized and reported to be isostructural and hexagonal (Kamath & Udupa, 1983). However, the detailed structural analysis was not given. The crystal structures of neodymium, europium and erbium complexes of N-acetylglycine have been reported (Zeng & Pan, 1992). The compounds were found to be isostructural and trigonal.

In the title compound, the Sm^III atom, lying on a threefold rotation axis, is coordinated by six O atoms from three carboxylate groups and three O atoms from three water molecules (Fig. 1). The three chelated carboxylate rings are completely staggered. The three Sm—O(water) bonds are also completely staggered with the same angle of 78.2 (2)° between two such bonds (Table 1). The angle O1—C1—O2 is 120.8 (6)°, while the angle subtended at Sm by the carboxylate O atoms (O1—Sm1—O2) is 51.4 (1)°. The bond distances between the two carboxylate O atoms and the Sm atom differ by only 0.033 Å. The bond lengths of the two carboxylate O atoms to the C atom are almost identical. The carboxylate group is thus resonance stabilized and functions symmetrically as a bidentate chelate. Apart from the carboxylate group, the bond distances and bond angles of N-acetylglycinate moiety in the title compound are not significantly different from those of free N-acetylglycine and its copper (Udupa & Krebs, 1978), neodymium, europium and erbium complexes (Zeng & Pan, 1992).

The title compound is isostructural with its terbium (Kameshwar et al., 2007), neodymium, europium and erbium analogues (Zeng & Pan, 1992). The coordination geometry in the title compound can be described in terms of a 4,4,4-tricapped triangular prism.

Related literature

For related compounds, see: Kamath & Udupa (1983); Kameshwar et al. (2007); Udupa & Krebs (1978); Zeng & Pan (1992).

S2. Experimental

The title compound was synthesized by adding samarium carbonate (0.376 g, 2.5 mmol) to N-acetylglycine (0.878 g, 7.5 mmol) dissolved in 50 ml water and allowing to react on a steam bath till the carbonate dissolved. A few mg of the carbonate were added to ensure that no unreacted acid was present. The unreacted carbonate was filtered off and the filtrate was evaporated naturally at ambient temperature. The crystals suitable for X-ray diffraction were picked up and dried in air. Analysis, calculated for C₁₂H₂₄N₃O₁₂Sm: C 26.08, H 4.38, N 7.60, Sm 27.20%; found: C 25.89, H 4.31, N 7.42, Sm 26.91%.

S3. Refinement

H atoms of the methyl group were positioned geometrically and refined as riding atoms, with C—H = 0.96 Å and U_iso(H) = 1.5U_eq(C). The other H atoms were found in a difference Fourier map and refined isotropically.

Computing details

Data collection: WinAFC (Rigaku/MSC, 2004); cell refinement: WinAFC (Rigaku/MSC, 2004); data reduction: CrystalStructure (Rigaku/MSC, 2004); 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 the title compound. Displacement ellipsoids are drawn at the 50% probability level. [Symmetry codes: (i) 2 - y, 1 + x-y, z; (ii) 1 - x + y, 2 - x, z.]

Tris(N-acetylglycinato-κ²O,O')triaquasamarium(III)

Crystal data

[Sm(C4H6NO3)3(H2O)3]	Dx = 1.935 Mg m^−3 Dm = 1.932 Mg m^−3 Dm measured by flotation method
Mr = 552.69	Mo Kα radiation, λ = 0.71069 Å
Trigonal, R3	Cell parameters from 25 reflections
Hall symbol: R 3	θ = 12.7–16.7°
a = 16.580 (4) Å	µ = 3.16 mm^−1
c = 5.978 (1) Å	T = 298 K
V = 1423.2 (5) Å^3	Needle, colourless
Z = 3	0.40 × 0.20 × 0.20 mm
F(000) = 825

Data collection

Rigaku AFC-7S diffractometer	702 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.029
Graphite monochromator	θmax = 27.5°, θmin = 3.7°
ω/2θ scans	h = −21→18
Absorption correction: ψ scan (North et al., 1968)	k = 0→21
Tmin = 0.364, Tmax = 0.570	l = −7→4
1396 measured reflections	3 standard reflections every 150 reflections
900 independent reflections	intensity decay: 0.6%

Refinement

Refinement on F^2	Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: full	H atoms treated by a mixture of independent and constrained refinement
R[F^2 > 2σ(F^2)] = 0.020	w = 1/[σ^2(Fo^2) + (0.0395P)^2] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.051	(Δ/σ)max < 0.001
S = 1.07	Δρmax = 0.81 e Å^−3
900 reflections	Δρmin = −1.21 e Å^−3
107 parameters	Extinction correction: SHELXL97 (Sheldrick, 1997), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
3 restraints	Extinction coefficient: 0.0017 (4)
Primary atom site location: structure-invariant direct methods	Absolute structure: Flack (1983), with 176 Friedel pairs
Secondary atom site location: difference Fourier map	Absolute structure parameter: −0.03 (2)

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

	x	y	z	Uiso*/Ueq
C4	0.7757 (5)	0.6593 (4)	−0.1291 (10)	0.0392 (13)
H4C	0.7402	0.5934	−0.1548	0.059*
H4A	0.8165	0.6890	−0.2538	0.059*
H4B	0.7343	0.6836	−0.1124	0.059*
O2	0.9222 (3)	0.8784 (3)	0.3629 (7)	0.0286 (8)
O1	0.9998 (3)	0.8499 (3)	0.6168 (6)	0.0296 (8)
C1	0.9635 (6)	0.8361 (5)	0.4255 (11)	0.0244 (14)
O4	1.0216 (3)	1.1147 (4)	0.9427 (7)	0.0309 (9)
H1	0.938 (6)	0.771 (5)	−0.046 (13)	0.05 (2)*
H2A	0.968 (5)	0.716 (5)	0.371 (11)	0.035 (17)*
H2B	1.039 (5)	0.808 (4)	0.214 (10)	0.029 (16)*
H2W	0.997 (8)	1.109 (9)	1.064 (10)	0.11 (5)*
H1W	1.051 (7)	1.1708 (19)	0.921 (17)	0.04 (3)*
Sm1	1.0000	1.0000	0.6673	0.01945 (14)
N1	0.9221 (3)	0.7447 (3)	0.0689 (8)	0.0284 (10)
O3	0.7980 (3)	0.6347 (3)	0.2547 (7)	0.0371 (10)
C3	0.8321 (4)	0.6779 (3)	0.0787 (9)	0.0285 (11)
C2	0.9797 (4)	0.7734 (4)	0.2680 (9)	0.0282 (10)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C4	0.046 (3)	0.037 (3)	0.031 (3)	0.018 (3)	−0.009 (3)	−0.004 (2)
O2	0.034 (2)	0.0271 (19)	0.0256 (19)	0.0162 (18)	−0.0032 (17)	0.0001 (15)
O1	0.039 (2)	0.032 (2)	0.0205 (19)	0.0195 (17)	−0.0054 (15)	−0.0001 (15)
C1	0.025 (3)	0.022 (3)	0.021 (3)	0.009 (2)	0.002 (2)	0.004 (2)
O4	0.037 (2)	0.028 (2)	0.022 (2)	0.011 (2)	0.0082 (18)	−0.0022 (19)
Sm1	0.02189 (15)	0.02189 (15)	0.01455 (18)	0.01095 (8)	0.000	0.000
N1	0.039 (3)	0.022 (2)	0.018 (2)	0.0109 (19)	0.0003 (18)	−0.0006 (17)
O3	0.041 (2)	0.030 (2)	0.030 (2)	0.0095 (18)	0.0049 (18)	0.0062 (16)
C3	0.037 (3)	0.017 (2)	0.028 (3)	0.011 (2)	0.000 (2)	−0.0023 (19)
C2	0.034 (3)	0.024 (2)	0.025 (2)	0.013 (2)	0.002 (2)	−0.001 (2)

Geometric parameters (Å, º)

C4—C3	1.491 (8)	Sm1—O4^ii	2.403 (4)
C4—H4C	0.9600	Sm1—O1^i	2.505 (4)
C4—H4A	0.9600	Sm1—O1^ii	2.505 (4)
C4—H4B	0.9600	Sm1—O2^ii	2.538 (4)
O2—C1	1.258 (8)	Sm1—O2^i	2.538 (4)
O2—Sm1	2.538 (4)	Sm1—C1^ii	2.863 (8)
O1—C1	1.258 (9)	Sm1—C1^i	2.863 (8)
O1—Sm1	2.505 (4)	N1—C3	1.342 (7)
C1—C2	1.522 (9)	N1—C2	1.450 (7)
C1—Sm1	2.863 (8)	N1—H1	0.79 (7)
O4—Sm1	2.403 (4)	O3—C3	1.239 (6)
O4—H2W	0.81 (8)	C2—H2A	1.06 (7)
O4—H1W	0.82 (2)	C2—H2B	0.91 (6)
Sm1—O4^i	2.403 (4)
C3—C4—H4C	109.5	O1^i—Sm1—O2^i	51.42 (12)
C3—C4—H4A	109.5	O1^ii—Sm1—O2^i	124.04 (13)
H4C—C4—H4A	109.5	O1—Sm1—O2^i	78.72 (14)
C3—C4—H4B	109.5	O2—Sm1—O2^i	74.26 (14)
H4C—C4—H4B	109.5	O2^ii—Sm1—O2^i	74.26 (14)
H4A—C4—H4B	109.5	O4—Sm1—C1	166.99 (15)
C1—O2—Sm1	91.6 (4)	O4^i—Sm1—C1	90.7 (2)
C1—O1—Sm1	93.1 (4)	O4^ii—Sm1—C1	92.91 (19)
O2—C1—O1	120.8 (6)	O1^i—Sm1—C1	120.94 (17)
O2—C1—C2	121.9 (6)	O1^ii—Sm1—C1	101.65 (19)
O1—C1—C2	117.1 (6)	O1—Sm1—C1	26.03 (17)
O2—C1—Sm1	62.4 (4)	O2—Sm1—C1	26.05 (18)
O1—C1—Sm1	60.9 (3)	O2^ii—Sm1—C1	98.17 (17)
C2—C1—Sm1	159.2 (5)	O2^i—Sm1—C1	70.74 (18)
Sm1—O4—H2W	131 (9)	O4—Sm1—C1^ii	90.7 (2)
Sm1—O4—H1W	124 (7)	O4^i—Sm1—C1^ii	92.9 (2)
H2W—O4—H1W	104 (10)	O4^ii—Sm1—C1^ii	166.99 (15)
O4—Sm1—O4^i	78.2 (2)	O1^i—Sm1—C1^ii	101.65 (19)
O4—Sm1—O4^ii	78.2 (2)	O1^ii—Sm1—C1^ii	26.03 (17)
O4^i—Sm1—O4^ii	78.2 (2)	O1—Sm1—C1^ii	120.94 (17)
O4—Sm1—O1^i	67.44 (15)	O2—Sm1—C1^ii	70.74 (18)
O4^i—Sm1—O1^i	142.61 (16)	O2^ii—Sm1—C1^ii	26.05 (18)
O4^ii—Sm1—O1^i	80.61 (16)	O2^i—Sm1—C1^ii	98.17 (17)
O4—Sm1—O1^ii	80.61 (16)	C1—Sm1—C1^ii	96.75 (18)
O4^i—Sm1—O1^ii	67.44 (15)	O4—Sm1—C1^i	92.9 (2)
O4^ii—Sm1—O1^ii	142.61 (16)	O4^i—Sm1—C1^i	166.99 (16)
O1^i—Sm1—O1^ii	118.57 (4)	O4^ii—Sm1—C1^i	90.7 (2)
O4—Sm1—O1	142.61 (16)	O1^i—Sm1—C1^i	26.03 (17)
O4^i—Sm1—O1	80.61 (16)	O1^ii—Sm1—C1^i	120.94 (17)
O4^ii—Sm1—O1	67.44 (15)	O1—Sm1—C1^i	101.65 (19)
O1^i—Sm1—O1	118.57 (4)	O2—Sm1—C1^i	98.17 (17)
O1^ii—Sm1—O1	118.57 (4)	O2^ii—Sm1—C1^i	70.74 (18)
O4—Sm1—O2	159.32 (14)	O2^i—Sm1—C1^i	26.05 (18)
O4^i—Sm1—O2	93.23 (15)	C1—Sm1—C1^i	96.75 (18)
O4^ii—Sm1—O2	118.80 (14)	C1^ii—Sm1—C1^i	96.75 (18)
O1^i—Sm1—O2	124.04 (13)	C3—N1—C2	120.9 (5)
O1^ii—Sm1—O2	78.72 (14)	C3—N1—H1	115 (6)
O1—Sm1—O2	51.42 (12)	C2—N1—H1	123 (6)
O4—Sm1—O2^ii	93.23 (15)	O3—C3—N1	120.8 (5)
O4^i—Sm1—O2^ii	118.80 (14)	O3—C3—C4	122.0 (5)
O4^ii—Sm1—O2^ii	159.32 (14)	N1—C3—C4	117.2 (5)
O1^i—Sm1—O2^ii	78.72 (14)	N1—C2—C1	114.8 (5)
O1^ii—Sm1—O2^ii	51.42 (12)	N1—C2—H2A	112 (4)
O1—Sm1—O2^ii	124.04 (13)	C1—C2—H2A	103 (4)
O2—Sm1—O2^ii	74.26 (14)	N1—C2—H2B	104 (4)
O4—Sm1—O2^i	118.80 (14)	C1—C2—H2B	107 (4)
O4^i—Sm1—O2^i	159.32 (14)	H2A—C2—H2B	115 (6)
O4^ii—Sm1—O2^i	93.23 (15)
Sm1—O2—C1—O1	17.9 (7)	O1—C1—Sm1—O4^ii	11.7 (4)
Sm1—O2—C1—C2	−156.5 (6)	C2—C1—Sm1—O4^ii	−78.4 (13)
Sm1—O1—C1—O2	−18.1 (7)	O2—C1—Sm1—O1^i	−105.1 (4)
Sm1—O1—C1—C2	156.5 (5)	O1—C1—Sm1—O1^i	92.5 (3)
C1—O1—Sm1—O4	167.7 (4)	C2—C1—Sm1—O1^i	2.4 (14)
C1—O1—Sm1—O4^i	111.6 (5)	O2—C1—Sm1—O1^ii	28.8 (4)
C1—O1—Sm1—O4^ii	−167.4 (4)	O1—C1—Sm1—O1^ii	−133.7 (4)
C1—O1—Sm1—O1^i	−102.7 (4)	C2—C1—Sm1—O1^ii	136.2 (13)
C1—O1—Sm1—O1^ii	53.8 (4)	O2—C1—Sm1—O1	162.5 (7)
C1—O1—Sm1—O2	9.7 (4)	C2—C1—Sm1—O1	−90.1 (14)
C1—O1—Sm1—O2^ii	−7.0 (4)	O1—C1—Sm1—O2	−162.5 (7)
C1—O1—Sm1—O2^i	−69.0 (4)	C2—C1—Sm1—O2	107.4 (14)
C1—O1—Sm1—C1^ii	23.8 (5)	O2—C1—Sm1—O2^ii	−23.4 (4)
C1—O1—Sm1—C1^i	−81.5 (5)	O1—C1—Sm1—O2^ii	174.2 (4)
C1—O2—Sm1—O4	−149.6 (4)	C2—C1—Sm1—O2^ii	84.1 (13)
C1—O2—Sm1—O4^i	−85.0 (4)	O2—C1—Sm1—O2^i	−93.5 (5)
C1—O2—Sm1—O4^ii	−6.7 (5)	O1—C1—Sm1—O2^i	104.1 (4)
C1—O2—Sm1—O1^i	91.8 (4)	C2—C1—Sm1—O2^i	14.0 (13)
C1—O2—Sm1—O1^ii	−151.3 (4)	O2—C1—Sm1—C1^ii	2.9 (4)
C1—O2—Sm1—O1	−9.7 (4)	O1—C1—Sm1—C1^ii	−159.6 (4)
C1—O2—Sm1—O2^ii	155.9 (4)	C2—C1—Sm1—C1^ii	110.3 (12)
C1—O2—Sm1—O2^i	78.2 (5)	O2—C1—Sm1—C1^i	−94.8 (3)
C1—O2—Sm1—C1^ii	−177.0 (4)	O1—C1—Sm1—C1^i	102.8 (5)
C1—O2—Sm1—C1^i	88.7 (3)	C2—C1—Sm1—C1^i	12.7 (14)
O2—C1—Sm1—O4	127.5 (8)	C2—N1—C3—O3	−5.1 (8)
O1—C1—Sm1—O4	−34.9 (12)	C2—N1—C3—C4	174.2 (5)
C2—C1—Sm1—O4	−125.0 (12)	C3—N1—C2—C1	−76.6 (7)
O2—C1—Sm1—O4^i	95.9 (4)	O2—C1—C2—N1	−17.3 (9)
O1—C1—Sm1—O4^i	−66.6 (4)	O1—C1—C2—N1	168.2 (6)
C2—C1—Sm1—O4^i	−156.7 (13)	Sm1—C1—C2—N1	−112.9 (13)
O2—C1—Sm1—O4^ii	174.1 (5)

Symmetry codes: (i) −y+2, x−y+1, z; (ii) −x+y+1, −x+2, z.