Tris­[2-(benzoyl­amino)­ethyl]­amine

Tris­[2-(benzoyl­amino)­ethyl]­amine [alternatively, N,N',N''-(nitrilo­tri­ethyl)­tri­benz­amide], C₂₇H₃₀N₄O₃, adopts a folded structure, forming a symmetrical cavity with an average depth of 7.3 Å and width ranging from 4.1-4.4 Å. The folded structure is a result of one intramolecular N-H...O hydrogen bond. A linear chain motif along the c axis best describes the extended intermolecular N-H...O hydrogen bonding.

S1. Comment

Compounds with amidate donor groups are useful for the stabilization of high valent metals. Additionally, tripodal type ligand structures are useful for enforcing trigonal pyramidal (or similar) geometry in metal complexes. Tris[2-(benzoylamino)ethyl]amine, (I), was synthesized as a tris-amidate tripodal amine-type ligand for the stabilization of high valent metal complexes with trigonal–pyramidal geometry. \scheme

The molecular structure of (I) is similar to the tripodal amine compounds, tris(3-aza-4-oxo-5-hydroxy-5-phenylpent-1-yl)amine, (II) (Byrne et al., 1998), and tris[(4-diphenylphosphinobenzamido)ethyl]amine, (III) (Lang et al., 1995). Compound (I) exhibits a folded structure due to the presence of an intramolecular N1···O2 hydrogen bond. When (I) is viewed down the molecule towards N4, one observes a symmetrical cavity with a average depth of 7.3 Å (distance from N4 to p-phenyl carbons) with closest N···N contact distances between the three arms of 4.1–4.4 Å. This may lead to a restriction in reactivity or solvent accessibility within the cavity since upon metallation of the ligand it is presumed that the three donor arms fold down into the expected tripod motif thereby encapsulating the metal within the cavity.

The folded structure is also observed in (II) and (III), exhibiting one or two intramolecular hydrogen bonds. A symmetrical cavity is observed for (III) (N···P distances of approximately 8.8 Å and closest N···N contact distances between the arms ranging 4.2–4.6 Å). On the other hand, an asymmetrical cavity is observed for (II) due to the presence of the two intramolecular hydrogen bonds `pulling back' the arms which would possibly allow for greater accessibility into the cavity.

In contrast, an extended structure is observed for [N-(1-propan-2-one oxime)]bis[N-2-(N',N''-trimethylacetyl)aminoethyl]amine, (IV) (Goldcamp et al., 2000), and tris[N-(S)-(-)-(α)-methylbenzylcarbamoylmethyl]amine, (IV) (Hammes et al., 1998), which is attributed to the lack of intramolecular hydrogen bonding. This extended structure allows for easy access for metal and solvent interactions.

In addition to the intramolecular hydrogen bond, (I) participates in two intermolecular N—H···O hydrogen bonds (N2···O3 and N3···O1) forming linear chains along the c axis.

S2. Experimental

The synthesis of (I) and related tripodal amines were first described by Valiyaveettil et al. (1993) starting from tris(aminoethyl)amine and reacting it with the appropriate acid chloride in the presence of triethylamine. An alternate route to the preparation of (I) is described here. To a solution of tris(2-aminoethyl)amine (1.00 g, 6.84 mmol) in chloroform (20 ml) at 273 K was added a solution of benzoic anhydride (4.80 g, 21.2 mmol) in chloroform (20 ml). The reaction was stirred for 3 h and the temperature was allowed to gradually increase to room temperature. The solvent was then removed by rotary evaporation, leaving a yellow coloured oil. This oil was washed with four 20 ml portions of diethyl ether until an off-white solid was obtained, which was then filtered to yield (I) (2.97 g, 6.48 mmol, 95% yield). Crystals suitable for diffraction were obtained from DMF–acetone. ¹H NMR (250 MHz, d₆-DMSO): 2.73 (t, 6H), 3.48 (q, 6H), 7.36–7.49 (m, 9H), 7.81 (d, 6H), 8.37 (t, 3H) p.p.m. IR (CH₂Cl₂): 3349 (w), 3325 (m, br), 3056 (w), 2947 (w), 2824 (m), 1650 (s), 1529 (s), 1296 (m), 1165 (w), 1072 (w) cm⁻¹. M.p. 419–421 K.

S3. Refinement

The H-atom positions were either located directly or calculated based on geometric criterion and allowed to ride on their respective atoms. H-atom U values were assigned as 1.2U_eq of the parent atom.

Computing details

Data collection: P3-P4/PC (Siemens, 1989); cell refinement: P3-P4/PC; data reduction: XDISK (Siemens, 1989); program(s) used to solve structure: SHELXTL (Sheldrick, 1994); program(s) used to refine structure: SHELXTL; software used to prepare material for publication: SHELXTL.

tris-(2-benzoylamino-ethyl)amine

Crystal data

C27H30N4O3	Dx = 1.250 Mg m^−3
Mr = 458.55	Melting point = 419–421 K
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
a = 10.004 (2) Å	Cell parameters from 40 reflections
b = 17.151 (4) Å	θ = 5.0–15.0°
c = 14.472 (3) Å	µ = 0.08 mm^−1
β = 101.06 (2)°	T = 293 K
V = 2437.0 (9) Å^3	Block, colourless
Z = 4	0.40 × 0.40 × 0.20 mm
F(000) = 976

Data collection

Siemens P3 diffractometer	Rint = 0.030
Radiation source: normal-focus sealed tube	θmax = 27.6°, θmin = 2.3°
Graphite monochromator	h = 0→13
θ–2θ scans	k = 0→22
5938 measured reflections	l = −18→18
5625 independent reflections	3 standard reflections every 300 reflections
2590 reflections with I > 2σ(I)	intensity decay: none

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)] = 0.059	Hydrogen site location: mixed
wR(F^2) = 0.165	H-atom parameters constrained
S = 1.00	w = 1/[σ^2(Fo^2) + (0.0605P)^2 + 0.5052P] where P = (Fo^2 + 2Fc^2)/3
4975 reflections	(Δ/σ)max = −0.001
307 parameters	Δρmax = 0.16 e Å^−3
0 restraints	Δρmin = −0.23 e Å^−3

Special details

Experimental. Crystals suitable for diffraction were grown from DMF-acetone. For the crystallographic experiment, a crystal of approximately 0.40 x 0.40 x 0.30 mm was cut from a much larger chunk and mounted on a glass fiber with epoxy resin.

Data were collected using variable speed θ–2θ scans (3.0–30.0°/min), and corrected for decay (min. 0.990, max. 1.023), Lorentz and polarization effects but not for absorption.

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 on F² for ALL reflections diffracting out to 0.80 Å resolution (650 reflections were excluded in the 0.75–0.80 Å resolution range due to very weak diffraction–approximately 100 reflections were above the σ(I) threshold).

Weighted R-factors wR and all goodnesses 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-factor(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
O1	0.3735 (2)	0.07346 (12)	0.53485 (12)	0.0603 (6)
O2	0.2793 (2)	0.13250 (12)	0.19870 (13)	0.0549 (5)
O3	0.6724 (2)	−0.03697 (13)	0.12240 (13)	0.0708 (7)
N1	0.3405 (2)	0.05056 (13)	0.37971 (15)	0.0488 (6)
H1	0.3522 (2)	0.06729 (13)	0.32580 (15)	0.059*
N2	0.3029 (2)	0.06210 (13)	0.07149 (14)	0.0461 (6)
H2	0.3468 (2)	0.05592 (13)	0.02642 (14)	0.055*
N3	0.6208 (2)	−0.07060 (14)	0.26062 (15)	0.0488 (6)
H3	0.6315 (2)	−0.06003 (14)	0.31967 (15)	0.059*
N4	0.3119 (2)	−0.06074 (12)	0.22652 (14)	0.0399 (5)
C1	0.2081 (3)	−0.0488 (2)	0.2841 (2)	0.0470 (7)
H1A	0.1603 (3)	−0.0976 (2)	0.2877 (2)	0.056*
H1B	0.1423 (3)	−0.0111 (2)	0.2530 (2)	0.056*
C2	0.2645 (3)	−0.0206 (2)	0.3832 (2)	0.0493 (7)
H2A	0.1903 (3)	−0.0114 (2)	0.4162 (2)	0.059*
H2B	0.3235 (3)	−0.0602 (2)	0.4173 (2)	0.059*
C3	0.3932 (3)	0.0914 (2)	0.4562 (2)	0.0429 (7)
C4	0.4786 (3)	0.1597 (2)	0.4417 (2)	0.0439 (7)
C5	0.4832 (3)	0.2234 (2)	0.5007 (2)	0.0533 (8)
H5	0.4329 (3)	0.2231 (2)	0.5484 (2)	0.064*
C6	0.5611 (3)	0.2870 (2)	0.4896 (3)	0.0700 (10)
H6	0.5617 (3)	0.3298 (2)	0.5290 (3)	0.084*
C7	0.6385 (4)	0.2882 (2)	0.4210 (3)	0.0834 (12)
H7	0.6910 (4)	0.3316 (2)	0.4134 (3)	0.100*
C8	0.6369 (4)	0.2238 (3)	0.3633 (3)	0.0918 (14)
H8	0.6907 (4)	0.2234 (3)	0.3175 (3)	0.110*
C9	0.5566 (3)	0.1602 (2)	0.3730 (2)	0.0686 (10)
H9	0.5551 (3)	0.1176 (2)	0.3331 (2)	0.082*
C10	0.2474 (3)	−0.0685 (2)	0.1270 (2)	0.0490 (7)
H10A	0.1715 (3)	−0.1044 (2)	0.1221 (2)	0.059*
H10B	0.3127 (3)	−0.0911 (2)	0.0931 (2)	0.059*
C11	0.1961 (3)	0.0075 (2)	0.0802 (2)	0.0496 (7)
H11A	0.1440 (3)	−0.0036 (2)	0.0179 (2)	0.060*
H11B	0.1351 (3)	0.0317 (2)	0.1163 (2)	0.060*
C12	0.3362 (3)	0.1220 (2)	0.1308 (2)	0.0440 (7)
C13	0.4424 (3)	0.1773 (2)	0.1111 (2)	0.0427 (6)
C14	0.4415 (4)	0.2520 (2)	0.1455 (3)	0.0753 (11)
H14	0.3752 (4)	0.2664 (2)	0.1792 (3)	0.090*
C15	0.5377 (4)	0.3058 (2)	0.1305 (3)	0.0827 (12)
H15	0.5356 (4)	0.3560 (2)	0.1543 (3)	0.099*
C16	0.6351 (3)	0.2861 (2)	0.0815 (2)	0.0601 (8)
H16	0.6994 (3)	0.3225 (2)	0.0710 (2)	0.072*
C17	0.6373 (3)	0.2118 (2)	0.0476 (2)	0.0697 (10)
H17	0.7044 (3)	0.1977 (2)	0.0144 (2)	0.084*
C18	0.5416 (3)	0.1573 (2)	0.0621 (2)	0.0613 (9)
H18	0.5445 (3)	0.1070 (2)	0.0384 (2)	0.074*
C19	0.3949 (3)	−0.1292 (2)	0.2579 (2)	0.0499 (7)
H19A	0.3425 (3)	−0.1755 (2)	0.2364 (2)	0.060*
H19B	0.4142 (3)	−0.1301 (2)	0.3261 (2)	0.060*
C20	0.5281 (3)	−0.1325 (2)	0.2235 (2)	0.0554 (8)
H20A	0.5715 (3)	−0.1822 (2)	0.2413 (2)	0.067*
H20B	0.5095 (3)	−0.1295 (2)	0.1553 (2)	0.067*
C21	0.6907 (3)	−0.0290 (2)	0.2082 (2)	0.0455 (7)
C22	0.7934 (3)	0.0278 (2)	0.2572 (2)	0.0463 (7)
C23	0.8325 (4)	0.0326 (2)	0.3535 (2)	0.0682 (10)
H23	0.7916 (4)	0.0005 (2)	0.3919 (2)	0.082*
C24	0.9322 (4)	0.0848 (2)	0.3937 (3)	0.0882 (12)
H24	0.9585 (4)	0.0870 (2)	0.4589 (3)	0.106*
C25	0.9926 (4)	0.1331 (2)	0.3387 (3)	0.0796 (11)
H25	1.0580 (4)	0.1690 (2)	0.3663 (3)	0.096*
C26	0.9567 (4)	0.1284 (2)	0.2441 (3)	0.0758 (10)
H26	0.9988 (4)	0.1604 (2)	0.2063 (3)	0.091*
C27	0.8584 (3)	0.0765 (2)	0.2033 (2)	0.0636 (9)
H27	0.8348 (3)	0.0740 (2)	0.1380 (2)	0.076*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.087 (2)	0.0652 (14)	0.0333 (10)	−0.0064 (12)	0.0224 (10)	−0.0002 (10)
O2	0.0655 (13)	0.0624 (13)	0.0431 (11)	−0.0045 (11)	0.0262 (10)	−0.0023 (9)
O3	0.102 (2)	0.078 (2)	0.0374 (11)	−0.0126 (14)	0.0250 (12)	−0.0080 (11)
N1	0.067 (2)	0.0511 (15)	0.0322 (12)	−0.0116 (13)	0.0191 (11)	−0.0019 (10)
N2	0.0534 (15)	0.0511 (14)	0.0357 (12)	−0.0028 (12)	0.0135 (11)	0.0016 (11)
N3	0.0507 (14)	0.060 (2)	0.0365 (12)	−0.0045 (13)	0.0107 (11)	−0.0057 (11)
N4	0.0468 (13)	0.0382 (12)	0.0364 (11)	−0.0055 (11)	0.0119 (10)	−0.0033 (10)
C1	0.048 (2)	0.047 (2)	0.049 (2)	−0.0098 (14)	0.0162 (14)	0.0004 (13)
C2	0.064 (2)	0.048 (2)	0.0405 (15)	−0.0049 (15)	0.0212 (14)	0.0020 (13)
C3	0.048 (2)	0.048 (2)	0.0341 (14)	0.0077 (13)	0.0108 (12)	−0.0014 (12)
C4	0.045 (2)	0.052 (2)	0.0347 (14)	0.0014 (14)	0.0067 (12)	−0.0027 (13)
C5	0.056 (2)	0.053 (2)	0.050 (2)	0.000 (2)	0.0088 (15)	−0.0042 (14)
C6	0.071 (2)	0.061 (2)	0.073 (2)	−0.014 (2)	0.002 (2)	−0.011 (2)
C7	0.082 (3)	0.087 (3)	0.075 (3)	−0.040 (2)	−0.001 (2)	0.005 (2)
C8	0.085 (3)	0.126 (4)	0.072 (2)	−0.048 (3)	0.033 (2)	−0.015 (2)
C9	0.071 (2)	0.082 (2)	0.059 (2)	−0.022 (2)	0.028 (2)	−0.016 (2)
C10	0.058 (2)	0.046 (2)	0.043 (2)	−0.0121 (15)	0.0091 (13)	−0.0077 (13)
C11	0.050 (2)	0.061 (2)	0.0362 (15)	−0.008 (2)	0.0034 (13)	0.0005 (14)
C12	0.049 (2)	0.048 (2)	0.0362 (14)	0.0041 (14)	0.0103 (13)	0.0054 (13)
C13	0.051 (2)	0.044 (2)	0.0347 (14)	0.0050 (14)	0.0119 (12)	0.0038 (12)
C14	0.086 (3)	0.051 (2)	0.105 (3)	−0.002 (2)	0.061 (2)	−0.013 (2)
C15	0.097 (3)	0.046 (2)	0.124 (3)	−0.004 (2)	0.067 (3)	−0.013 (2)
C16	0.063 (2)	0.052 (2)	0.071 (2)	−0.008 (2)	0.027 (2)	−0.001 (2)
C17	0.066 (2)	0.072 (2)	0.080 (2)	−0.012 (2)	0.038 (2)	−0.022 (2)
C18	0.061 (2)	0.055 (2)	0.074 (2)	−0.007 (2)	0.028 (2)	−0.018 (2)
C19	0.058 (2)	0.039 (2)	0.054 (2)	−0.0043 (14)	0.0138 (15)	0.0012 (14)
C20	0.060 (2)	0.052 (2)	0.056 (2)	0.000 (2)	0.013 (2)	−0.0073 (15)
C21	0.052 (2)	0.050 (2)	0.0368 (15)	0.0096 (14)	0.0145 (13)	−0.0028 (13)
C22	0.048 (2)	0.049 (2)	0.045 (2)	0.0080 (14)	0.0174 (14)	0.0004 (13)
C23	0.082 (2)	0.073 (2)	0.048 (2)	−0.021 (2)	0.009 (2)	0.003 (2)
C24	0.101 (3)	0.094 (3)	0.063 (2)	−0.033 (3)	−0.002 (2)	−0.004 (2)
C25	0.073 (3)	0.070 (3)	0.095 (3)	−0.020 (2)	0.015 (2)	−0.005 (2)
C26	0.080 (3)	0.065 (2)	0.091 (3)	−0.011 (2)	0.038 (2)	0.001 (2)
C27	0.072 (2)	0.070 (2)	0.056 (2)	0.000 (2)	0.030 (2)	0.001 (2)

Geometric parameters (Å, º)

O1—C3	1.231 (3)	C7—C8	1.383 (5)
O2—C12	1.239 (3)	C8—C9	1.378 (5)
O3—C21	1.228 (3)	C10—C11	1.513 (4)
N1—C3	1.331 (3)	C12—C13	1.492 (4)
N1—C2	1.444 (3)	C13—C18	1.370 (4)
N2—C12	1.339 (3)	C13—C14	1.374 (4)
N2—C11	1.443 (3)	C14—C15	1.380 (4)
N3—C21	1.333 (3)	C15—C16	1.353 (4)
N3—C20	1.444 (4)	C16—C17	1.367 (4)
N4—C19	1.458 (3)	C17—C18	1.383 (4)
N4—C1	1.465 (3)	C19—C20	1.510 (4)
N4—C10	1.467 (3)	C21—C22	1.492 (4)
C1—C2	1.517 (4)	C22—C23	1.376 (4)
C3—C4	1.489 (4)	C22—C27	1.388 (4)
C4—C9	1.377 (4)	C23—C24	1.382 (5)
C4—C5	1.382 (4)	C24—C25	1.368 (5)
C5—C6	1.367 (4)	C25—C26	1.350 (5)
C6—C7	1.371 (5)	C26—C27	1.373 (5)
C3—N1—C2	122.9 (2)	N2—C12—C13	117.6 (2)
C12—N2—C11	122.6 (2)	C18—C13—C14	118.5 (3)
C21—N3—C20	123.5 (2)	C18—C13—C12	123.5 (3)
C19—N4—C1	111.0 (2)	C14—C13—C12	118.0 (3)
C19—N4—C10	110.5 (2)	C13—C14—C15	120.9 (3)
C1—N4—C10	110.1 (2)	C16—C15—C14	120.6 (3)
N4—C1—C2	114.0 (2)	C15—C16—C17	118.9 (3)
N1—C2—C1	109.9 (2)	C16—C17—C18	121.1 (3)
O1—C3—N1	122.0 (3)	C13—C18—C17	120.0 (3)
O1—C3—C4	121.7 (2)	N4—C19—C20	114.4 (2)
N1—C3—C4	116.3 (2)	N3—C20—C19	113.2 (2)
C9—C4—C5	119.0 (3)	O3—C21—N3	121.5 (3)
C9—C4—C3	121.8 (3)	O3—C21—C22	120.6 (3)
C5—C4—C3	119.2 (2)	N3—C21—C22	117.9 (2)
C6—C5—C4	120.7 (3)	C23—C22—C27	117.4 (3)
C5—C6—C7	120.7 (3)	C23—C22—C21	123.8 (3)
C6—C7—C8	118.8 (3)	C27—C22—C21	118.7 (3)
C9—C8—C7	120.7 (3)	C22—C23—C24	120.5 (3)
C4—C9—C8	120.0 (3)	C25—C24—C23	120.8 (4)
N4—C10—C11	114.2 (2)	C26—C25—C24	119.5 (4)
N2—C11—C10	113.9 (2)	C25—C26—C27	120.2 (3)
O2—C12—N2	121.6 (3)	C26—C27—C22	121.6 (3)
O2—C12—C13	120.7 (3)
C19—N4—C1—C2	71.6 (3)	N2—C12—C13—C14	155.3 (3)
C10—N4—C1—C2	−165.7 (2)	C18—C13—C14—C15	0.4 (5)
C3—N1—C2—C1	175.0 (2)	C12—C13—C14—C15	179.4 (3)
N4—C1—C2—N1	56.4 (3)	C13—C14—C15—C16	0.1 (6)
C2—N1—C3—O1	−4.4 (4)	C14—C15—C16—C17	−0.5 (6)
C2—N1—C3—C4	175.0 (2)	C15—C16—C17—C18	0.6 (5)
O1—C3—C4—C9	146.9 (3)	C14—C13—C18—C17	−0.3 (5)
N1—C3—C4—C9	−32.5 (4)	C12—C13—C18—C17	−179.3 (3)
O1—C3—C4—C5	−31.0 (4)	C16—C17—C18—C13	−0.1 (5)
N1—C3—C4—C5	149.6 (3)	C1—N4—C19—C20	−162.6 (2)
C9—C4—C5—C6	1.8 (5)	C10—N4—C19—C20	75.0 (3)
C3—C4—C5—C6	179.7 (3)	C21—N3—C20—C19	−135.0 (3)
C4—C5—C6—C7	−1.4 (5)	N4—C19—C20—N3	65.1 (3)
C5—C6—C7—C8	−0.3 (6)	C20—N3—C21—O3	5.7 (4)
C6—C7—C8—C9	1.6 (6)	C20—N3—C21—C22	−174.0 (2)
C5—C4—C9—C8	−0.5 (5)	O3—C21—C22—C23	−171.0 (3)
C3—C4—C9—C8	−178.4 (3)	N3—C21—C22—C23	8.7 (4)
C7—C8—C9—C4	−1.2 (6)	O3—C21—C22—C27	6.0 (4)
C19—N4—C10—C11	−162.1 (2)	N3—C21—C22—C27	−174.3 (3)
C1—N4—C10—C11	74.9 (3)	C27—C22—C23—C24	0.4 (5)
C12—N2—C11—C10	−100.0 (3)	C21—C22—C23—C24	177.5 (3)
N4—C10—C11—N2	66.5 (3)	C22—C23—C24—C25	0.8 (6)
C11—N2—C12—O2	2.2 (4)	C23—C24—C25—C26	−1.6 (6)
C11—N2—C12—C13	−176.3 (2)	C24—C25—C26—C27	1.3 (6)
O2—C12—C13—C18	155.8 (3)	C25—C26—C27—C22	0.0 (6)
N2—C12—C13—C18	−25.7 (4)	C23—C22—C27—C26	−0.8 (5)
O2—C12—C13—C14	−23.2 (4)	C21—C22—C27—C26	−178.1 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O2	0.86	2.16	2.932 (3)	150
N2—H2···O3^i	0.86	2.15	2.896 (3)	145
N3—H3···O1^ii	0.86	2.13	2.950 (3)	160

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