Tris(2-succin­imido­ethyl)­amine hydrate (1/0.075)

The title compound, C₁₈H₂₄N₄O₆·0.075H₂O, (I), was prepared as part of a research programme to prepare and identify new tripodal ligands which exhibit instability at low pH, thereby releasing coordinated metal cations under such conditions. Each mol­ecule lies on a crystallographic threefold axis with the three arms arranged in the form of a claw. Angles within the five-membered succin­imide ring, where the r.m.s. deviation of the five atoms from the least-squares ring plane is only 0.004 Å, vary from 104.8 (3)° at a methyl­ene C atom to 112.7 (3)° at the formally sp² N atom. The structure contains a partially occupied disordered water mol­ecule, the source of which is presumably the water produced as a by-product of the synthetic reaction.

Key indicators

• Single-crystal X-ray study
• T = 210 K
• Mean [sigma](C-C) = 0.006 Å
• H-atom completeness 100%
• Disorder in solvent or counterion
• R factor = 0.071
• wR factor = 0.144
• Data-to-parameter ratio = 13.1

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


 Alert Level C:



RINTA_01  Alert C The value of Rint is greater than 0.10
          Rint given   0.137

WEIGH_01  Alert C Extra text has been found in the
          _refine_ls_weighting_scheme field. This should be in the
          _refine_ls_weighting_details field.
          Weighting scheme given as calc w = 1/[\s^2^(Fo^2^)+(0.023P)^2^+9.981P
          Weighting scheme identified as calc

PLAT_302  Alert C Anion/Solvent Disorder .......................      15.00 Perc.

General Notes



FORMU_01  There is a discrepancy between the atom counts in the
          _chemical_formula_sum and the formula from the _atom_site* data.
          Atom count from _chemical_formula_sum:C18 H24.15 N4 O6.075
          Atom count from the _atom_site data:  C18 H24 N4 O6.075

CELLZ_01
         From the CIF: _cell_formula_units_Z    6
         From the CIF: _chemical_formula_sum  C18 H24.15 N4 O6.075
         TEST: Compare cell contents of formula and atom_site data

         atom    Z*formula  cif sites diff
         C        108.00    108.00    0.00
         H        144.90    144.00    0.90
         N         24.00     24.00    0.00
         O         36.45     36.45    0.00
          Difference between formula and atom_site contents detected.
          WARNING: H atoms missing from atom site list. Is this intentional?


 0 Alert Level A = Potentially serious problem

 0 Alert Level B = Potential problem

 3 Alert Level C = Please check

---

S1. Comment

No comment

S2. Experimental

Tris(2-aminoethylamine) (0.146 g, 1.00 mmol) and succinic anhydride (0.300 g, 3.00 mmol) were heated under reflux in benzene (70 ml) for 12 h. Upon cooling, colourless hexagonal crystals of the title compound were formed.

S3. Refinement

At convergence of a refinement model containing no hydration, a peak of 0.66 e Å^-3 was observed, approximately three times the size of other peaks and troughs in the difference Fourier synthesis. This feature was modelled isotropically as the O atom of a partially occupied water molecule. However, its occupancy of the 3 site at (2/3,1/3,1/3) refined to only 0.15 (2), corresponding to a 0.075-hydrate. Water H atoms were not located; methylene H atoms were introduced at geometrically calculated positions and allowed to ride 0.98 Å from their parent atoms with U_iso(H) = 1.2U_eq(C).

Computing details

Data collection: STADI-4 (Stoe & Cie, 1996); cell refinement: STADI-4; data reduction: X-RED (Stoe & Cie, 1996); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2001); software used to prepare material for publication: SHELXL97 and PLATON.

Figures

Fig. 1. A view of the title compound showing atom-numbering scheme and displacement ellipsoids drawn at the 20% probability level. For clarity, the partially occupied water molecule and all H atoms have been omitted.

(I)

Crystal data

C18H24N4O6·0.075H2O	Dx = 1.376 Mg m^−3
Mr = 393.67	Mo Kα radiation, λ = 0.71073 Å
Trigonal, R3	Cell parameters from 29 reflections
a = 13.200 (2) Å	θ = 25.1–29.6°
c = 18.874 (5) Å	µ = 0.11 mm^−1
V = 2848.0 (10) Å^3	T = 210 K
Z = 6	Hexagonal plate, colourless
F(000) = 1251	0.39 × 0.32 × 0.06 mm

Data collection

Stoe Stadi-4 four-circle diffractometer	Rint = 0.137
Radiation source: fine-focus sealed tube	θmax = 25.0°, θmin = 2.1°
Graphite monochromator	h = −15→15
ω/θ scans	k = −7→15
1343 measured reflections	l = 0→22
1128 independent reflections	3 standard reflections every 60 min
738 reflections with I > 2σ(I)	intensity decay: none

Refinement

Refinement on F^2	Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: full	H-atom parameters constrained
R[F^2 > 2σ(F^2)] = 0.071	Calculated w = 1/[σ^2(Fo^2) + (0.023P)^2 + 9.981P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.144	(Δ/σ)max = 0.001
S = 1.28	Δρmax = 0.23 e Å^−3
1128 reflections	Δρmin = −0.20 e Å^−3
86 parameters	Extinction correction: SHELXL97
0 restraints	Extinction coefficient: none
Primary atom site location: structure-invariant direct methods

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	Occ. (<1)
N	0.6667	0.3333	0.1103 (3)	0.0243 (12)
C1	0.7327 (3)	0.4542 (3)	0.13715 (19)	0.0278 (9)
H1A	0.7475	0.4519	0.1878	0.033*
H1B	0.6841	0.4907	0.1320	0.033*
C2	0.8483 (3)	0.5302 (3)	0.10021 (19)	0.0312 (10)
H2A	0.8935	0.6022	0.1276	0.037*
H2B	0.8926	0.4889	0.0995	0.037*
N3	0.8358 (3)	0.5608 (3)	0.02792 (15)	0.0252 (8)
C4	0.8483 (3)	0.5087 (3)	−0.0324 (2)	0.0312 (10)
O4	0.8693 (3)	0.4293 (3)	−0.03229 (16)	0.0481 (9)
C5	0.8325 (4)	0.5687 (4)	−0.0957 (2)	0.0371 (10)
H5A	0.7677	0.5124	−0.1253	0.045*
H5B	0.9039	0.6060	−0.1244	0.045*
C6	0.8059 (4)	0.6595 (4)	−0.0659 (2)	0.0336 (10)
H6A	0.8649	0.7382	−0.0811	0.040*
H6B	0.7287	0.6443	−0.0815	0.040*
C7	0.8088 (3)	0.6474 (3)	0.0129 (2)	0.0307 (9)
O7	0.7909 (3)	0.7015 (3)	0.05829 (15)	0.0442 (9)
O1W	0.6667	0.3333	0.3333	0.08 (3)*	0.15

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N	0.0255 (18)	0.0255 (18)	0.022 (3)	0.0128 (9)	0.000	0.000
C1	0.031 (2)	0.028 (2)	0.025 (2)	0.0145 (18)	0.0005 (17)	−0.0033 (17)
C2	0.030 (2)	0.031 (2)	0.031 (2)	0.0130 (19)	−0.0047 (18)	0.0020 (18)
N3	0.0265 (18)	0.0225 (17)	0.0245 (17)	0.0107 (14)	−0.0005 (14)	0.0003 (14)
C4	0.021 (2)	0.029 (2)	0.038 (2)	0.0079 (17)	0.0009 (17)	−0.0076 (18)
O4	0.058 (2)	0.0395 (18)	0.058 (2)	0.0326 (17)	0.0079 (17)	−0.0028 (16)
C5	0.036 (2)	0.044 (3)	0.032 (2)	0.020 (2)	−0.003 (2)	−0.001 (2)
C6	0.031 (2)	0.033 (2)	0.035 (2)	0.015 (2)	−0.0010 (18)	0.0086 (19)
C7	0.026 (2)	0.023 (2)	0.040 (2)	0.0103 (18)	−0.0011 (18)	−0.0014 (18)
O7	0.058 (2)	0.0383 (18)	0.0453 (19)	0.0312 (17)	−0.0014 (15)	−0.0080 (15)

Geometric parameters (Å, º)

N—C1^i	1.474 (4)	C6—C7	1.499 (5)
N—C1	1.474 (4)	C7—O7	1.211 (5)
N—C1^ii	1.474 (4)	C1—H1A	0.9800
C1—C2	1.513 (5)	C1—H1B	0.9800
C2—N3	1.455 (4)	C2—H2A	0.9800
N3—C4	1.381 (5)	C2—H2B	0.9800
N3—C7	1.387 (5)	C5—H5A	0.9800
C4—O4	1.210 (5)	C5—H5B	0.9800
C4—C5	1.505 (5)	C6—H6A	0.9800
C5—C6	1.515 (5)	C6—H6B	0.9800
C1^i—N—C1	108.9 (2)	N—C1—H1B	108.6
C1^i—N—C1^ii	108.9 (2)	C2—C1—H1B	108.7
C1—N—C1^ii	108.9 (2)	H1A—C1—H1B	107.6
N—C1—C2	114.4 (3)	N3—C2—H2A	108.8
N3—C2—C1	113.6 (3)	C1—C2—H2A	108.8
C4—N3—C7	112.7 (3)	N3—C2—H2B	108.9
C4—N3—C2	125.2 (3)	C1—C2—H2B	108.9
C7—N3—C2	122.1 (3)	H2A—C2—H2B	107.7
O4—C4—N3	124.4 (4)	C4—C5—H5A	110.6
O4—C4—C5	127.5 (4)	C6—C5—H5A	110.6
N3—C4—C5	108.0 (3)	C4—C5—H5B	110.6
C4—C5—C6	105.7 (3)	C6—C5—H5B	110.6
C7—C6—C5	104.8 (3)	H5A—C5—H5B	108.7
O7—C7—N3	123.2 (4)	C7—C6—H6A	110.8
O7—C7—C6	128.0 (4)	C5—C6—H6A	110.8
N3—C7—C6	108.7 (3)	C7—C6—H6B	110.8
N—C1—H1A	108.6	C5—C6—H6B	110.8
C2—C1—H1A	108.7	H6A—C6—H6B	108.9
C1^i—N—C1—C2	75.6 (5)	O4—C4—C5—C6	179.0 (4)
C1^ii—N—C1—C2	−165.9 (3)	N3—C4—C5—C6	−1.5 (4)
N—C1—C2—N3	70.8 (4)	C4—C5—C6—C7	0.4 (4)
C1—C2—N3—C4	−101.7 (4)	C4—N3—C7—O7	177.9 (4)
C1—C2—N3—C7	77.9 (5)	C2—N3—C7—O7	−1.8 (6)
C7—N3—C4—O4	−178.3 (4)	C4—N3—C7—C6	−2.0 (4)
C2—N3—C4—O4	1.4 (6)	C2—N3—C7—C6	178.4 (3)
C7—N3—C4—C5	2.2 (4)	C5—C6—C7—O7	−179.0 (4)
C2—N3—C4—C5	−178.1 (3)	C5—C6—C7—N3	0.9 (4)

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