Chromate de 2,2-diméthylpropylènediammonium

The crystal structure of the title compound, 2,2-dimethyl-1,3-propanediammonium chromate, (C₅H₁₆N₂)[CrO₄], consists of layers built up from CrO₄^2- tetrahedra alternating with diprotonated 2,2-dimethylpropylendiamine molecules. N-H...O hydrogen bonds ensure the cohesion and stability of the structure.

S1. Comment

Comparés aux phosphates organiques, les chromates organiques sont très peu étudiés. A notre connaissance, seule la structure des deux composés a été établie. Il s'agit de (CN₃H₆)₂[CrO₄] (Cygler et al., 1976) et (C₈H₂₄N₂)[CrO₄].xH₂O (x = 2; 0.5; Sorehkin et al., 1978). Nous avons isolé une nouvelle phase (C₅H₁₆N₂)[CrO₄], (I), dont la préparation et l'étude structurale font l'objet du présent travail. L'unité asymétrique du composé (I) contient un ion chromate [CrO₄]²⁻ et un cation organique C₅H₁₆N₂²⁺.

La structure de (I) renferme des couches anioniques de tétraèdres chromates [CrO₄]²⁻ parallèles aux plans (110) alternées avec des couches organiques contenant la base diprotonnée C₅H₁₆N₂²⁺. Les groupements (–NH₃)⁺ sont insérés entre ces tétraèdres et peuvent être considérés comme leur appartenant. Il en résulte une couche formée de constituants inorganiques: (–NH₃)⁺ et [CrO₄]²⁻ dont la cohésion est assurée par des liaisons hydrogène de type N—H···O (Tableau 2). Le tétraèdre chromate est régulier, les distances des liaisons Cr—O vairent entre 1.616 (2) e t 1.687 (3) Å. Ces valeurs sont en accord avec celles rencontrées dans d'autres chromates (Cygler et al., 1976; Stephens & Cruickshank, 1970; Riou & Roult, 1979; Khan & Baur, 1972). Les angles des liaisons O—Cr—O dont les valeurs sont comprises entre 108.5 (1) e t 110.2 (1)° ne subissent que de faibles écarts par rapport à la valeur théorique 109.47°. Les moyennes des longueurs de liaisons C—N et C—H sont respectivement 1.494 (4) e t 0.947 (7) Å. Ces valeurs sont comparables á celle rencontrées dans le composé (CN₃H₆)₂[CrO₄] (Cygler et al., 1976).

S2. Experimental

Le composé (C₅H₁₆N₂)[CrO₄] a été préparé à partir d'un mélange de C₅H₁₄N₂ (3 g), CrO₃ (3 g) et H₂O (40 g) dans les proportions molaire respectives 1:1:77. Le mélange réactionnel obtenu est maintenu sous agitation magnétique, puis transvasé dans un cristallisoir. Après quelques jours d'évaporation à température ambiante, on obtient des cristaux en forme de plaquettes de couleur jaune.

Computing details

Data collection: CAD-4 EXPRESS (Duisenberg, 1992; Macicek & Yordanov, 1992); cell refinement: CAD-4 EXPRESS; data reduction: MolEN (Fair, 1990); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); software used to prepare material for publication: SHELXL97.

2,2-dimethyl-1,3-propanediammonium chromate

Crystal data

(C5H16N2)[CrO4]	Z = 2
Mr = 220.20	F(000) = 232
Triclinic, P1	Dx = 1.588 Mg m^−3
a = 9.082 (1) Å	Mo Kα radiation, λ = 0.71069 Å
b = 9.789 (2) Å	Cell parameters from 25 reflections
c = 5.741 (8) Å	θ = 2.2–26.0°
α = 104.92 (1)°	µ = 1.22 mm^−1
β = 93.20 (1)°	T = 293 K
γ = 109.06 (1)°	Plaquette, yellow
V = 460.6 (7) Å^3	0.90 × 0.54 × 0.36 mm

Data collection

CAD-4 diffractometer	1477 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.018
Graphite monochromator	θmax = 26.0°, θmin = 2.3°
ω/2θ scans	h = −11→11
Absorption correction: ψ scan (North et al., 1968)	k = −11→12
Tmin = 0.463, Tmax = 0.644	l = −7→0
1984 measured reflections	2 standard reflections every 120 min
1795 independent reflections	intensity decay: 0.8%

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)] = 0.035	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.088	All H-atom parameters refined
S = 1.12	Calculated w = 1/[σ^2(Fo^2) + (0.0339P)^2 + 0.3143P] where P = (Fo^2 + 2Fc^2)/3
1795 reflections	(Δ/σ)max = 0.001
174 parameters	Δρmax = 0.31 e Å^−3
0 restraints	Δρmin = −0.29 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
Cr	0.22995 (5)	0.22602 (5)	0.04191 (8)	0.0178 (2)
O1	0.0974 (2)	0.3032 (2)	0.1161 (4)	0.0296 (5)
O2	0.2113 (2)	0.1608 (2)	−0.2643 (3)	0.0232 (4)
O3	0.4106 (2)	0.3533 (2)	0.1468 (4)	0.0280 (5)
O4	0.2053 (3)	0.0889 (2)	0.1610 (4)	0.0340 (5)
N1	0.4938 (3)	0.3380 (3)	−0.3763 (5)	0.0215 (5)
N2	0.9499 (3)	0.1576 (3)	−0.5507 (5)	0.0237 (5)
C1	0.6330 (3)	0.3010 (3)	−0.3004 (5)	0.0216 (6)
C2	0.8606 (3)	0.2303 (3)	−0.3802 (5)	0.0227 (6)
C3	0.7237 (3)	0.2571 (3)	−0.5083 (5)	0.0171 (5)
C4	0.7862 (4)	0.3875 (4)	−0.6205 (6)	0.0254 (6)
C5	0.6191 (4)	0.1130 (4)	−0.7057 (6)	0.0294 (7)
H1N1	0.517 (4)	0.432 (5)	−0.307 (7)	0.036 (10)*
H2N1	0.487 (4)	0.338 (4)	−0.532 (7)	0.037 (10)*
H3N1	0.412 (5)	0.271 (4)	−0.343 (7)	0.040 (10)*
H1N2	1.029 (4)	0.153 (4)	−0.480 (6)	0.027 (9)*
H2N2	0.984 (4)	0.203 (4)	−0.661 (6)	0.029 (9)*
H3N2	0.900 (5)	0.063 (5)	−0.623 (7)	0.039 (10)*
H1C1	0.594 (3)	0.222 (3)	−0.224 (5)	0.018 (7)*
H2C1	0.698 (4)	0.384 (4)	−0.174 (6)	0.027 (8)*
H1C2	0.932 (4)	0.326 (4)	−0.281 (6)	0.022 (8)*
H2C2	0.825 (4)	0.167 (4)	−0.278 (6)	0.024 (8)*
H1C4	0.857 (4)	0.365 (4)	−0.741 (6)	0.032 (9)*
H2C4	0.704 (4)	0.401 (4)	−0.705 (6)	0.036 (10)*
H3C4	0.837 (5)	0.477 (5)	−0.497 (7)	0.043 (10)*
H1C5	0.598 (4)	0.029 (4)	−0.645 (7)	0.041 (10)*
H2C5	0.672 (4)	0.090 (4)	−0.836 (7)	0.035 (9)*
H3C5	0.526 (5)	0.121 (4)	−0.774 (7)	0.044 (10)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cr	0.0173 (2)	0.0208 (2)	0.0146 (2)	0.0080 (2)	0.0019 (2)	0.0024 (2)
O1	0.028 (1)	0.037 (1)	0.028 (1)	0.019 (1)	0.0078 (9)	0.0064 (9)
O2	0.021 (1)	0.029 (1)	0.015 (1)	0.0074 (8)	0.0021 (8)	0.0014 (8)
O3	0.021 (1)	0.028 (1)	0.025 (1)	0.0045 (9)	−0.0029 (8)	−0.0001 (9)
O4	0.042 (1)	0.033 (1)	0.033 (1)	0.016 (1)	0.011 (1)	0.016 (1)
N1	0.021 (1)	0.024 (1)	0.021 (1)	0.009 (1)	0.007 (1)	0.006 (1)
N2	0.018 (1)	0.026 (1)	0.029 (1)	0.011 (1)	0.002 (1)	0.007 (1)
C1	0.023 (1)	0.027 (1)	0.016 (1)	0.011 (1)	0.003 (1)	0.006 (1)
C2	0.023 (1)	0.029 (2)	0.018 (1)	0.013 (1)	0.002 (1)	0.005 (1)
C3	0.013 (1)	0.018 (1)	0.017 (1)	0.004 (1)	0.001 (1)	0.002 (1)
C4	0.021 (1)	0.032 (2)	0.027 (2)	0.010 (1)	0.006 (1)	0.014 (1)
C5	0.023 (2)	0.027 (2)	0.029 (2)	0.009 (1)	−0.002 (1)	−0.005 (1)

Geometric parameters (Å, º)

Cr—O4	1.616 (2)	C1—H1C1	0.97 (3)
Cr—O1	1.639 (2)	C1—H2C1	0.93 (3)
Cr—O3	1.666 (2)	C2—C3	1.538 (4)
Cr—O2	1.687 (3)	C2—H1C2	0.95 (3)
N1—C1	1.495 (4)	C2—H2C2	0.95 (3)
N1—H1N1	0.85 (4)	C3—C4	1.536 (4)
N1—H2N1	0.89 (4)	C3—C5	1.536 (4)
N1—H3N1	0.88 (4)	C4—H1C4	1.00 (4)
N2—C2	1.493 (4)	C4—H2C4	0.93 (4)
N2—H1N2	0.82 (4)	C4—H3C4	0.93 (4)
N2—H2N2	0.88 (4)	C5—H1C5	0.94 (4)
N2—H3N2	0.86 (4)	C5—H2C5	0.93 (4)
C1—C3	1.538 (4)	C5—H3C5	0.95 (4)
O4—Cr—O1	109.0 (1)	N2—C2—C3	114.1 (2)
O4—Cr—O3	109.2 (1)	N2—C2—H1C2	108.3 (19)
O1—Cr—O3	110.2 (1)	C3—C2—H1C2	107.6 (19)
O4—Cr—O2	110.1 (1)	N2—C2—H2C2	106.5 (19)
O1—Cr—O2	109.9 (9)	C3—C2—H2C2	111.6 (19)
O3—Cr—O2	108.5 (1)	H1C2—C2—H2C2	109 (3)
C1—N1—H1N1	106 (2)	C4—C3—C5	110.1 (3)
C1—N1—H2N1	111 (2)	C4—C3—C2	110.8 (2)
H1N1—N1—H2N1	99 (3)	C5—C3—C2	111.0 (2)
C1—N1—H3N1	105 (2)	C4—C3—C1	110.1 (2)
H1N1—N1—H3N1	120 (3)	C5—C3—C1	111.1 (2)
H2N1—N1—H3N1	114 (3)	C2—C3—C1	103.6 (2)
C2—N2—H1N2	113 (2)	C3—C4—H1C4	110.7 (19)
C2—N2—H2N2	115 (2)	C3—C4—H2C4	111 (2)
H1N2—N2—H2N2	105 (3)	H1C4—C4—H2C4	107 (3)
C2—N2—H3N2	114 (2)	C3—C4—H3C4	109 (2)
H1N2—N2—H3N2	100 (3)	H1C4—C4—H3C4	112 (3)
H2N2—N2—H3N2	109 (3)	H2C4—C4—H3C4	107 (3)
N1—C1—C3	114.5 (2)	C3—C5—H1C5	110 (2)
N1—C1—H1C1	106.6 (18)	C3—C5—H2C5	111 (2)
C3—C1—H1C1	111.7 (18)	H1C5—C5—H2C5	104 (3)
N1—C1—H2C1	108 (2)	C3—C5—H3C5	113 (2)
C3—C1—H2C1	111 (2)	H1C5—C5—H3C5	113 (3)
H1C1—C1—H2C1	104 (3)	H2C5—C5—H3C5	105 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H3N1···O2	0.89 (4)	1.93 (4)	2.803 (3)	167 (3)
N2—H2N2···O1^i	0.88 (4)	1.94 (4)	2.816 (4)	169 (3)

Symmetry code: (i) x+1, y, z−1.