Tris(2-ammonio­ethyl)­amine tribromide

The title compound, [N(CH₂CH₂NH₃)₃]Br₃, is a salt of a triprotonated tetr­amine. The tertiary amine N atom sits on a threefold axis, as do the three bromide anions. Each of the primary amines is protonated, while the tertiary amine is not protonated. The compound is isostructural with the chloride and the perchlorate analogs.

Key indicators

• Single-crystal X-ray study
• T = 100 K
• Mean [sigma](C-C) = 0.007 Å
• R factor = 0.063
• wR factor = 0.145
• Data-to-parameter ratio = 33.4

checkCIF/PLATON results

No syntax errors found



Alert level A
PLAT035_ALERT_1_A No _chemical_absolute_configuration info given .          ?

Author Response: ...see _publ_section_exptl_refinement.

Alert level B
ABSTM02_ALERT_3_B  The ratio of expected to reported Tmax/Tmin(RR) is > 1.50
            Tmin and Tmax reported:      0.164     0.218
            Tmin and Tmax expected:      0.107     0.217
            RR =      1.529
            Please check that your absorption correction is appropriate.
PLAT060_ALERT_3_B Ratio Tmax/Tmin (Exp-to-Rep) (too) Large .......       1.52

Alert level C
CRYSC01_ALERT_1_C The word below has not been recognised as a standard
            identifier.
            tan
CRYSC01_ALERT_1_C No recognised colour has been given for crystal colour.
PLAT042_ALERT_1_C Calc. and Rep. MoietyFormula Strings Differ ....          ?
PLAT341_ALERT_3_C Low Bond Precision on C-C bonds (x 1000) Ang ...          7
PLAT790_ALERT_4_C Centre of Gravity not Within Unit Cell: Resd.  #          2
              Br

Alert level G
REFLT03_ALERT_1_G ALERT: Expected hkl max differ from CIF values
           From the CIF: _diffrn_reflns_theta_max           35.54
           From the CIF: _reflns_number_total               1598
           From the CIF: _diffrn_reflns_limit_ max hkl   18.   12.   12.
           From the CIF: _diffrn_reflns_limit_ min hkl  -18.  -12.  -12.
           TEST1: Expected hkl limits for theta max
           Calculated maximum hkl   18.   18.   18.
           Calculated minimum hkl  -18.  -18.  -18.
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           35.54
           From the CIF: _reflns_number_total               1598
           Count of symmetry unique reflns         1166
           Completeness (_total/calc)            137.05%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured       432
           Fraction of Friedel pairs measured     0.370
           Are heavy atom types Z>Si present          yes

   1 ALERT level A = In general: serious problem
   2 ALERT level B = Potentially serious problem
   5 ALERT level C = Check and explain
   2 ALERT level G = General alerts; check

   5 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
   3 ALERT type 3 Indicator that the structure quality may be low
   2 ALERT type 4 Improvement, methodology, query or suggestion

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Computing details

Data collection: COLLECT (Nonius 2000); cell refinement: DENZO and SCALEPACK version 1.96.2 (Otwinowski & Minor, 1997); data reduction: DENZO and SCALEPACK version 1.96.2 (Otwinowski & Minor, 1997); program(s) used to solve structure: SIR92 (Altomare, et al. 1993); program(s) used to refine structure: TEXSAN for Windows version 1.06 (MSC, 1997-1999); software used to prepare material for publication: TEXSAN for Windows version 1.06 (MSC, 1997-1999).

(I)

Crystal data

C6H21N4·3(Br)	Dx = 1.921 Mg m^−3
Mr = 388.97	Mo Kα radiation, λ = 0.7107 Å
Cubic, P213	Cell parameters from 1167 reflections
Hall symbol: P 2ac 2ab 3	θ = 2.5–35.5°
a = 11.038 (2) Å	µ = 9.00 mm^−1
V = 1344.8 (4) Å^3	T = 100 K
Z = 4	Fragment, tan
F(000) = 760.0	0.27 × 0.22 × 0.17 mm

Data collection

KappaCCD (with Oxford Cryostream) diffractometer	1598 independent reflections
Radiation source: fine-focus sealed tube	1335 reflections with I > 3.00σ(I)
Graphite monochromator	Rint = 0.042
ω scans with κ offsets	θmax = 35.5°, θmin = 2.6°
Absorption correction: multi-scan HKL Scalepack (Otwinowski & Minor 1997)	h = −18→18
Tmin = 0.164, Tmax = 0.218	k = −12→12
14942 measured reflections	l = −12→12

Refinement

Refinement on F^2	0 restraints
Least-squares matrix: full	24 constraints
R[F^2 > 2σ(F^2)] = 0.063	H-atom parameters not refined
wR(F^2) = 0.145	Weighting scheme based on measured s.u.'s w = 1/[σ^2(Fo) + 0.00331|Fo|^2]
S = 1.09	(Δ/σ)max = 0.0002
1335 reflections	Δρmax = 0.73 e Å^−3
40 parameters	Δρmin = −1.36 e Å^−3

Special details

Refinement. Refinement of F². The weighted R-factor wR and goodness of fit are based on F², conventional R-factors R are based on F. R-factors based on F² are statistically about twice as large as those based on F.

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

	x	y	z	Uiso*/Ueq
Br1	−0.17771 (5)	−0.1777	−0.1777	0.01888 (4)
Br2	0.30081 (5)	0.3008	0.3008	0.01720 (4)
Br3	0.54581 (4)	0.5458	0.5458	0.01311 (4)
N1	0.0404 (4)	0.0139 (5)	−0.2475 (4)	0.0186 (9)
N2	0.0252 (4)	0.0252	0.0252	0.0087 (2)
C1	0.1445 (4)	0.0401 (5)	−0.1640 (4)	0.0128 (9)
C2	0.1009 (4)	0.1038 (4)	−0.0508 (5)	0.0132 (8)
H1	−0.0302	−0.0024	−0.2011	0.022*
H2	0.0593	−0.0546	−0.2962	0.022*
H3	0.0264	0.0821	−0.2981	0.022*
H4	0.1824	−0.0339	−0.1419	0.015*
H5	0.2014	0.0904	−0.2046	0.015*
H6	0.0548	0.1727	−0.0739	0.016*
H7	0.1693	0.1290	−0.0051	0.016*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Br1	0.0189 (2)	0.0189	0.0189	−0.0036 (2)	−0.0036	−0.0036
Br2	0.0171 (2)	0.0171	0.0171	0.0016 (5)	0.0016	−0.0016
Br3	0.0131 (2)	0.0131	0.0131	−0.0047 (5)	0.0047	−0.0047
N1	0.016 (2)	0.028 (2)	0.013 (2)	0.001 (2)	−0.001 (1)	−0.001 (2)
N2	0.0087 (10)	0.0087	0.0087	0.0006 (10)	0.0006	0.0006
C1	0.011 (2)	0.014 (2)	0.012 (2)	−0.001 (1)	0.0016 (13)	0.000 (1)
C2	0.013 (2)	0.008 (2)	0.019 (2)	−0.0016 (13)	0.003 (2)	0.000 (1)

Geometric parameters (Å, º)

N1—C1	1.501 (6)	N2—C2^ii	1.468 (5)
N1—H1	0.95	C1—C2	1.512 (7)
N1—H2	0.95	C1—H4	0.95
N1—H3	0.95	C1—H5	0.95
N2—C2	1.468 (5)	C2—H6	0.95
N2—C2^i	1.468 (5)	C2—H7	0.95
BR1···N1	3.296 (5)	BR2···H3^iv	2.805
BR1···H1	2.542	BR3···N1^iv	3.359 (4)
BR1···C1^iii	3.590 (5)	BR3···H2^iv	2.762
BR2···N1^iv	3.395 (5)
C2—N2—C2^i	109.1 (3)	N1—C1—H4	109.17
C2—N2—C2^ii	109.1 (3)	N1—C1—H5	109.17
C2^i—N2—C2^ii	109.1 (3)	C2—C1—H4	109.17
N1—C1—C2	110.7 (4)	C2—C1—H5	109.17
N2—C2—C1	112.3 (4)	H4—C1—H5	109.46
C1—N1—H1	109.47	N2—C2—H6	108.77
C1—N1—H2	109.47	N2—C2—H7	108.77
C1—N1—H3	109.47	C1—C2—H6	108.77
H1—N1—H2	109.47	C1—C2—H7	108.77
H1—N1—H3	109.47	H6—C2—H7	109.46
H2—N1—H3	109.47
N1—C1—C2—N2	67.4 (5)	C1—C2—N2—C2^ii	82.9 (6)
C1—C2—N2—C2^i	−158.0 (4)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···Br1	0.95	2.54	3.296 (5)	136
N1—H2···Br3^v	0.95	2.76	3.359 (4)	122
N1—H3···Br2^v	0.95	2.81	3.395 (5)	121

Symmetry code: (v) x−1/2, −y+1/2, −z.