[Bis(2-hydroxy­ethyl)­amino]­tris­(hydroxy­methyl)­methane (Bis–Tris), an important complexing agent

The title compound, (HOCH₂CH₂)₂NC(CH₂OH)₃ or C₈H₁₉NO₅, is an important complexing agent. All hydroxyl-H atoms are involved in intermolecular hydrogen bonds (O—H...O distances are in the range 2.690–2.847 Å), which link the mol­ecules in the crystal into a three-dimensional infinite network. One of the hydroxy­methyl hydroxyl groups also participates in an intramolecular O—H...N hydrogen bond, closing a five-membered N—C—C—O—H pseudo-cycle [O...N 2.7804 (16) Å and O—H...N 118.6 (17)°].

Key indicators

• Single-crystal X-ray study
• T = 203 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.034
• wR factor = 0.084
• Data-to-parameter ratio = 11.9

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


 Alert Level C:



ABSMU_01  Alert C The ratio of given/expected absorption coefficient lies
          outside the range 0.99 <> 1.01
          Calculated value of mu =     0.115
          Value of mu given      =     0.120


 0 Alert Level A = Potentially serious problem

 0 Alert Level B = Potential problem

 1 Alert Level C = Please check

---

S1. Comment

The title compound, (I), commonly called Bis-Tris, is an important polyalcohol used in the complexation of metal ions (Hong et al., 1995; Sigel et al., 1982; Scheller et al., 1980; Wesolowski & Palmer, 1989; Wesolowski et al., 1990). It has received special attention as a chelation agent for some lanthanide ions (Oh et al., 1998; Chen et al., 1997; Pfefferle & Bunzli, 1989). The structure of (I) was determined in the course of an ongoing investigation into the complexation properties of Bis-Tris with various lanthanide halides (Wood et al., 2000).

All five hydroxyl-H atoms in (I) (Fig. 1) are involved in intermolecular hydrogen bonds (Table 1), which link the molecules in the crystal of (I) into a three-dimensional infinite network. Fig. 2 shows the three-dimensional network down [010]. It can be seen from this direction that the hydrogen bonding is localized in regular supramolecular synthons (Desiraju & Steiner, 2001). One of these synthons is shown in Fig. 3 and Fig. 4.

The O3—H3 hydroxyl group also serves as a donor for an intramolecular O3—H3···N1 bond (see Table 1), thus giving rise to a bifurcated hydrogen bond and closing the five-membered N1—C1—C4—O3—H3 pseudo-cycle. There are two other possibilities for intramolecular hydrogen bonding in (I). However, the C4—H4B···O1 and C5—H5B···O2 interactions should in fact be classified as extremely weak, if existing at all. As these are not bifurcated, it appears that this bonding is geometrically unlikely in the former, and extremely weak in the latter case. The corresponding distances and angles, are, nevertheless, included in Table 1 for comparison.

S2. Experimental

The title compound was obtained commercially (Aldrich) and crystallized from a concentrated methanol solution.

S3. Refinement

All hydroxyl-H atoms were located and refined (O—H 0.78–0.84 Å). All the rest of the H atoms were placed geometrically and included in the refinement in the riding-motion approximation with displacement parameters equal to 1.2U_eq of the corresponding carrier atom.

Computing details

Data collection: SMART (Bruker, 1997–1998); cell refinement: SMART; data reduction: SAINT-Plus (Bruker, 1999); program(s) used to solve structure: XS in SHELXTL (Sheldrick, 1998); program(s) used to refine structure: XL in SHELXTL; molecular graphics: XP in SHELXTL; software used to prepare material for publication: XCIF in SHELXTL.

Figures

	Fig. 1. The molecular structure of (I) with atom labels and 30% probability ellipsoids for non-H atoms.
	Fig. 2. A view down [010] showing the extensive hydrogen bonding. Intermolecular interactions are indicated by dashed lines. Only H atoms involved in intermolecular interactions are shown.
	Fig. 3. A view of the hydrogen-bonding synthon parallel to the [010] direction. Only O and H atoms involved in hydrogen bonding are shown. O atoms are shown with 30% probability ellipsoids.
	Fig. 4. The hydrogen-bonding synthon viewed down [010]. Only O and H atoms involved in hydrogen bonding are shown. O atoms are shown with 30% probability ellipsoids.

(I)

Crystal data

C8H19NO5	Dx = 1.403 Mg m^−3
Mr = 209.24	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Pbca	Cell parameters from 1001 reflections
a = 12.1298 (17) Å	θ = 2.4–27.9°
b = 9.5303 (13) Å	µ = 0.12 mm^−1
c = 17.144 (2) Å	T = 203 K
V = 1981.9 (5) Å^3	Needle, colorless
Z = 8	0.32 × 0.20 × 0.11 mm
F(000) = 912

Data collection

Siemens SMART 1K diffractometer	1745 independent reflections
Radiation source: normal-focus sealed tube	1476 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.033
Detector resolution: 8.3 pixels mm^-1	θmax = 25.0°, θmin = 2.9°
ω scans	h = −14→11
Absorption correction: empirical (SADABS; Sheldrick, 1999)	k = −11→11
Tmin = 0.964, Tmax = 0.987	l = −20→16
14160 measured reflections

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)] = 0.034	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.084	H atoms treated by a mixture of independent and constrained refinement
S = 1.03	w = 1/[σ^2(Fo^2) + (0.0399P)^2 + 0.7334P] where P = (Fo^2 + 2Fc^2)/3
1745 reflections	(Δ/σ)max < 0.001
147 parameters	Δρmax = 0.24 e Å^−3
0 restraints	Δρmin = −0.18 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
N1	0.46638 (9)	0.21083 (11)	0.65075 (7)	0.0200 (3)
O1	0.58293 (9)	0.25164 (11)	0.45071 (6)	0.0273 (3)
O2	0.66745 (9)	0.04041 (11)	0.59010 (7)	0.0323 (3)
O3	0.46313 (10)	0.48513 (12)	0.59555 (7)	0.0355 (3)
O4	0.26258 (9)	−0.07991 (11)	0.62309 (7)	0.0305 (3)
O5	0.34000 (10)	0.38224 (12)	0.76953 (7)	0.0356 (3)
C1	0.55049 (11)	0.25295 (14)	0.59206 (8)	0.0208 (3)
C2	0.50554 (12)	0.21767 (14)	0.51044 (8)	0.0226 (3)
H2A	0.4882	0.1173	0.5079	0.027*
H2B	0.4371	0.2700	0.5016	0.027*
C3	0.66468 (12)	0.18757 (15)	0.60385 (9)	0.0262 (3)
H3A	0.7170	0.2335	0.5686	0.031*
H3B	0.6889	0.2058	0.6574	0.031*
C4	0.56531 (12)	0.41289 (14)	0.59709 (9)	0.0249 (3)
H4A	0.6043	0.4362	0.6454	0.030*
H4B	0.6108	0.4446	0.5532	0.030*
C5	0.42278 (12)	0.06642 (14)	0.64419 (8)	0.0213 (3)
H5A	0.4280	0.0206	0.6952	0.026*
H5B	0.4689	0.0135	0.6077	0.026*
C6	0.30439 (12)	0.06033 (15)	0.61667 (9)	0.0261 (3)
H6A	0.2592	0.1238	0.6483	0.031*
H6B	0.3002	0.0913	0.5622	0.031*
C7	0.49955 (12)	0.23876 (16)	0.73229 (8)	0.0263 (4)
H7A	0.5452	0.3236	0.7339	0.032*
H7B	0.5442	0.1603	0.7514	0.032*
C8	0.40143 (13)	0.25798 (15)	0.78508 (9)	0.0288 (4)
H8A	0.3526	0.1767	0.7795	0.035*
H8B	0.4270	0.2605	0.8393	0.035*
H5	0.3126 (16)	0.378 (2)	0.7262 (12)	0.043 (6)*
H4	0.3020 (18)	−0.132 (2)	0.5985 (12)	0.052 (6)*
H1	0.5710 (16)	0.334 (2)	0.4361 (11)	0.045 (5)*
H2	0.6681 (16)	0.000 (2)	0.6319 (13)	0.052 (6)*
H3	0.4167 (17)	0.433 (2)	0.6077 (11)	0.039 (6)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0210 (6)	0.0191 (6)	0.0200 (6)	−0.0019 (5)	0.0000 (5)	−0.0010 (5)
O1	0.0353 (6)	0.0212 (5)	0.0254 (6)	0.0043 (5)	0.0094 (5)	0.0029 (4)
O2	0.0321 (6)	0.0276 (6)	0.0371 (7)	0.0089 (5)	0.0037 (5)	0.0041 (5)
O3	0.0314 (7)	0.0196 (6)	0.0556 (8)	0.0025 (5)	0.0140 (6)	0.0083 (5)
O4	0.0257 (6)	0.0201 (5)	0.0457 (7)	−0.0051 (4)	0.0103 (5)	−0.0054 (5)
O5	0.0493 (8)	0.0316 (6)	0.0259 (7)	0.0111 (5)	0.0004 (6)	−0.0042 (5)
C1	0.0205 (7)	0.0194 (7)	0.0223 (8)	−0.0014 (6)	0.0007 (6)	0.0001 (5)
C2	0.0248 (8)	0.0199 (7)	0.0232 (8)	−0.0012 (6)	0.0018 (6)	0.0007 (6)
C3	0.0211 (8)	0.0278 (8)	0.0297 (8)	0.0005 (6)	0.0008 (6)	0.0015 (6)
C4	0.0253 (8)	0.0218 (7)	0.0275 (8)	−0.0020 (6)	0.0018 (6)	−0.0016 (6)
C5	0.0233 (8)	0.0177 (7)	0.0230 (7)	0.0004 (6)	0.0015 (6)	0.0018 (5)
C6	0.0227 (8)	0.0190 (7)	0.0368 (9)	−0.0031 (6)	0.0013 (7)	0.0012 (6)
C7	0.0292 (8)	0.0288 (8)	0.0210 (8)	−0.0021 (6)	−0.0029 (6)	−0.0010 (6)
C8	0.0370 (9)	0.0274 (8)	0.0220 (8)	0.0028 (7)	0.0010 (7)	−0.0007 (6)

Geometric parameters (Å, º)

N1—C5	1.4787 (17)	C2—H2A	0.9800
N1—C7	1.4788 (18)	C2—H2B	0.9800
N1—C1	1.4881 (18)	C3—H3A	0.9800
O1—C2	1.4264 (18)	C3—H3B	0.9800
O1—H1	0.84 (2)	C4—H4A	0.9800
O2—C3	1.4225 (18)	C4—H4B	0.9800
O2—H2	0.81 (2)	C5—C6	1.513 (2)
O3—C4	1.4179 (19)	C5—H5A	0.9800
O3—H3	0.78 (2)	C5—H5B	0.9800
O4—C6	1.4338 (17)	C6—H6A	0.9800
O4—H4	0.81 (2)	C6—H6B	0.9800
O5—C8	1.4243 (18)	C7—C8	1.506 (2)
O5—H5	0.82 (2)	C7—H7A	0.9800
C1—C3	1.5322 (19)	C7—H7B	0.9800
C1—C4	1.5373 (19)	C8—H8A	0.9800
C1—C2	1.539 (2)	C8—H8B	0.9800
C5—N1—C7	109.67 (11)	C1—C4—H4A	109.2
C5—N1—C1	116.41 (11)	O3—C4—H4B	109.2
C7—N1—C1	113.84 (11)	C1—C4—H4B	109.2
C2—O1—H1	108.3 (13)	H4A—C4—H4B	107.9
C3—O2—H2	108.8 (15)	N1—C5—C6	113.51 (11)
C4—O3—H3	108.4 (14)	N1—C5—H5A	108.9
C6—O4—H4	108.7 (15)	C6—C5—H5A	108.9
C8—O5—H5	110.2 (14)	N1—C5—H5B	108.9
N1—C1—C3	114.89 (11)	C6—C5—H5B	108.9
N1—C1—C4	108.04 (11)	H5A—C5—H5B	107.7
C3—C1—C4	106.86 (11)	O4—C6—C5	110.34 (12)
N1—C1—C2	108.24 (11)	O4—C6—H6A	109.6
C3—C1—C2	110.57 (11)	C5—C6—H6A	109.6
C4—C1—C2	108.00 (11)	O4—C6—H6B	109.6
O1—C2—C1	111.72 (12)	C5—C6—H6B	109.6
O1—C2—H2A	109.3	H6A—C6—H6B	108.1
C1—C2—H2A	109.3	N1—C7—C8	112.02 (12)
O1—C2—H2B	109.3	N1—C7—H7A	109.2
C1—C2—H2B	109.3	C8—C7—H7A	109.2
H2A—C2—H2B	107.9	N1—C7—H7B	109.2
O2—C3—C1	113.60 (12)	C8—C7—H7B	109.2
O2—C3—H3A	108.8	H7A—C7—H7B	107.9
C1—C3—H3A	108.8	O5—C8—C7	113.71 (13)
O2—C3—H3B	108.8	O5—C8—H8A	108.8
C1—C3—H3B	108.8	C7—C8—H8A	108.8
H3A—C3—H3B	107.7	O5—C8—H8B	108.8
O3—C4—C1	112.22 (12)	C7—C8—H8B	108.8
O3—C4—H4A	109.2	H8A—C8—H8B	107.7
C5—N1—C1—C3	−73.38 (15)	C2—C1—C3—O2	−54.49 (15)
C7—N1—C1—C3	55.70 (15)	N1—C1—C4—O3	−49.41 (15)
C5—N1—C1—C4	167.44 (11)	C3—C1—C4—O3	−173.55 (12)
C7—N1—C1—C4	−63.47 (14)	C2—C1—C4—O3	67.47 (15)
C5—N1—C1—C2	50.73 (14)	C7—N1—C5—C6	119.55 (13)
C7—N1—C1—C2	179.81 (11)	C1—N1—C5—C6	−109.40 (14)
N1—C1—C2—O1	−178.45 (10)	N1—C5—C6—O4	−171.18 (11)
C3—C1—C2—O1	−51.79 (15)	C5—N1—C7—C8	−73.36 (15)
C4—C1—C2—O1	64.81 (15)	C1—N1—C7—C8	154.22 (12)
N1—C1—C3—O2	68.38 (16)	N1—C7—C8—O5	−67.83 (16)
C4—C1—C3—O2	−171.79 (12)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···O3^i	0.84 (2)	1.86 (2)	2.6897 (16)	177 (2)
O2—H2···O5^ii	0.81 (2)	2.03 (2)	2.8410 (17)	174 (2)
O3—H3···N1	0.78 (2)	2.321 (19)	2.7804 (16)	118.6 (17)
O3—H3···O4^iii	0.78 (2)	2.19 (2)	2.8466 (17)	141.6 (18)
O4—H4···O1^iv	0.81 (2)	1.99 (2)	2.7913 (16)	171 (2)
O5—H5···O4^iii	0.82 (2)	2.03 (2)	2.8251 (17)	165.6 (19)
C4—H4B···O1	0.98	2.57	2.9505 (18)	103
C5—H5B···O2	0.98	2.44	3.1192 (18)	126

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