(2,6-Diiso­propyl­phenyl)­iso­propyl­idene­ammonium iodide

The title compound, C₁₄H₂₄N⁺·I^-, was formed by a Schiff base condensation of 2,6-diiso­propyl­aniline and acetone, using GaI as a Lewis acid. A strong interaction from the iminium hydrogen N-H to the iodide counter-ion is observed. The ¹H and ¹³C NMR data are also reported.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.007 Å
• R factor = 0.047
• wR factor = 0.099
• Data-to-parameter ratio = 18.0

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry

General Notes



ABSTM_02  When printed, the submitted absorption T values will be replaced
          by the scaled T values. Since the ratio of scaled T's is
          identical to the ratio of reported T values, the scaling does
          not imply a change to the absorption corrections used in the
          study.
          Ratio of Tmax expected/reported      1.384
          Tmax scaled      0.827 Tmin scaled      0.822

---

S1. Comment

We have been investigating the reactivity of GaI (Green et al., 1990) in C—C coupling reactions (Baker & Jones, 2003) and in the preparation of Ga^I N-heterocyclic carbene analogues (Baker et al., 2002).

In the course of our investigations, we have found that GaI can be used as a Lewis acid catalyst for the Schiff base condensation of a primary amine and a ketone. The Schiff base condensation reaction of an aldehyde or ketone with an amine is well known to be catalyzed by Lewis acids (Armesto et al., 1986). The addition of 2,6-diisopropylaniline to a suspension of GaI in toluene, followed by half an equivalent of acetone gives rise to the expected condensation product, (I). This presumably reacts further with HI to give the title product in good isolated yields.

The crystal structure of this salt displays a C1—N1 bond length in the expected range for compounds of this type (Scholz et al., 1993). There is a close contact which may be regarded as an N—H···Ibond [N1—H1 = 0.870 (19), H1···I1 2.57 (2), N1···I1 3.423 (4) Å and N1—H1···I1 167 (4)°].

S2. Experimental

To a solution of GaI (2.07 mmol) in toluene (10 ml) was added a solution of 2,6-diisopropylaniline (0.37 ml, 1.96 mmol) in toluene (10 ml), followed by a solution of acetone (0.07 ml, 1.02 mmol) in toluene (10 ml). After stirring for 4 h under argon, the solvent was removed under vacuum and the residue extracted with CH₂Cl₂ (20 ml). Concentration and cooling to 243 K afforded colourless blocks of the title compound (0.08 g, 23%, m.p. 414–417 K). IR (Nujol): ν_max 2965, 2664, 1935, 1835, 1724, 1654, 1589, 1558, 1460, 1373, 1252, 1167, 1076, 1046, 971, 931, 825, 793, 722 cm^{−1. 1}H NMR [400 MHz, CD₂Cl₂]: δ 1.13 (d, 6H, J = 6.89 Hz, CH₃), 1.20 (d, 6H, J = 6.82 Hz, CH₃), 2.14 (s, 3H, NCCH₃), 2.71 (sept, 2H, J = 6.79 Hz, CH), 3.04 (s, 3H, NCCH₃), 7.26 (d, 2H, J = 7.78, m-Ar), 7.42 (t, 1H, J = 11.18 Hz, p-Ar). ¹³C NMR [100 MHz, CD₂Cl₂]: δ 22.6 (CH₃), 23.7 ((CH₃)₂CN), 24.7 (CH₃), 24.9 [(CH₃)₂CN], 29.1 [CH(Me)₂], 124.8 (m-Ar), 129.8 (o-Ar), 131.1 (p-Ar), 143.1 (i-Ar), 193.9 (C—N). MS (APCI): m/z 218.0 (M⁺, 100%), 201.9 (M⁺—NH₂), 175.8 (M⁺—HC(Me)₂).

S3. Refinement

Atom H1, attached to N1, was refined isotropically, with a restrained N—H bond length. All other H atoms were positioned geometrically and refined with riding-model constraints.

Computing details

Data collection: COLLECT (Hooft, 2000); cell refinement: DENZO–SMN (Otwinowski & Minor, 1997); data reduction: DENZO–SMN; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: SHELXL97.

Figures

Fig. 1. The molecular structure of (I) with the atom-numbering scheme. Displacement ellipsoids are drawn at the 25% probability level.

(2,6-Diisopropylphenyl)isopropylideneammonium iodide

Crystal data

C15H24N^+·I^−	Dx = 1.368 Mg m^−3
Mr = 345.25	Melting point: 414 K
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 13.426 (3) Å	Cell parameters from 13 reflections
b = 11.128 (2) Å	θ = 2.9–25.0°
c = 12.211 (2) Å	µ = 1.89 mm^−1
β = 113.28 (3)°	T = 293 K
V = 1675.8 (6) Å^3	Block, colourless
Z = 4	0.10 × 0.10 × 0.10 mm
F(000) = 696

Data collection

Nonius KappaCCD diffractometer	2944 independent reflections
Radiation source: fine-focus sealed tube	2159 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.047
ϕ and ω scans	θmax = 25.1°, θmin = 3.3°
Absorption correction: multi-scan (SORTAV; Blessing, 1995)	h = −15→15
Tmin = 0.594, Tmax = 0.598	k = −13→13
8952 measured reflections	l = −14→13

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)] = 0.047	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.099	H atoms treated by a mixture of independent and constrained refinement
S = 1.07	w = 1/[σ^2(Fo^2) + (0.0144P)^2 + 2.3024P] where P = (Fo^2 + 2Fc^2)/3
2944 reflections	(Δ/σ)max = 0.001
164 parameters	Δρmax = 0.69 e Å^−3
1 restraint	Δρmin = −0.86 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
I1	0.55094 (3)	1.23878 (3)	−0.00119 (3)	0.07754 (18)
N1	0.6692 (3)	1.0746 (3)	0.2550 (3)	0.0470 (9)
C1	0.7855 (3)	1.0650 (4)	0.2924 (4)	0.0443 (10)
C2	0.8507 (4)	1.1594 (4)	0.3563 (4)	0.0514 (11)
C3	0.9608 (4)	1.1489 (5)	0.3854 (4)	0.0620 (13)
H3	1.0066	1.2106	0.4275	0.074*
C4	1.0044 (4)	1.0500 (5)	0.3539 (5)	0.0654 (13)
H4	1.0790	1.0446	0.3762	0.078*
C5	0.9375 (4)	0.9582 (4)	0.2889 (4)	0.0598 (12)
H5	0.9675	0.8919	0.2668	0.072*
C6	0.8263 (4)	0.9638 (4)	0.2564 (4)	0.0497 (11)
C7	0.8049 (4)	1.2707 (4)	0.3931 (5)	0.0614 (12)
H7	0.7283	1.2551	0.3757	0.074*
C8	0.8617 (6)	1.2955 (6)	0.5263 (5)	0.098 (2)
H8A	0.8565	1.2259	0.5701	0.147*
H8B	0.8278	1.3626	0.5471	0.147*
H8C	0.9367	1.3135	0.5455	0.147*
C9	0.8103 (6)	1.3794 (5)	0.3198 (6)	0.100 (2)
H9A	0.8848	1.4001	0.3391	0.150*
H9B	0.7739	1.4461	0.3377	0.150*
H9C	0.7758	1.3605	0.2365	0.150*
C10	0.7547 (4)	0.8635 (4)	0.1819 (4)	0.0598 (12)
H10	0.6802	0.8801	0.1731	0.072*
C11	0.7561 (5)	0.8635 (6)	0.0577 (5)	0.0890 (18)
H11A	0.7307	0.9397	0.0202	0.133*
H11B	0.7097	0.8007	0.0109	0.133*
H11C	0.8288	0.8500	0.0639	0.133*
C12	0.7870 (6)	0.7405 (5)	0.2418 (6)	0.0951 (19)
H12A	0.8590	0.7208	0.2491	0.143*
H12B	0.7371	0.6806	0.1943	0.143*
H12C	0.7851	0.7430	0.3196	0.143*
C13	0.6107 (4)	1.0251 (4)	0.3035 (4)	0.0528 (11)
C14	0.6601 (5)	0.9573 (5)	0.4152 (5)	0.0839 (17)
H14A	0.7355	0.9442	0.4325	0.126*
H14B	0.6241	0.8814	0.4072	0.126*
H14C	0.6531	1.0022	0.4789	0.126*
C15	0.4912 (4)	1.0351 (5)	0.2462 (5)	0.0731 (15)
H15A	0.4714	1.0903	0.1806	0.110*
H15B	0.4640	1.0638	0.3033	0.110*
H15C	0.4605	0.9576	0.2175	0.110*
H1	0.633 (3)	1.105 (3)	0.185 (2)	0.047 (12)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
I1	0.0681 (3)	0.0936 (3)	0.0689 (3)	0.0096 (2)	0.02507 (19)	0.0192 (2)
N1	0.040 (2)	0.049 (2)	0.049 (2)	0.0042 (17)	0.0151 (19)	0.0050 (18)
C1	0.035 (2)	0.049 (2)	0.048 (2)	0.0044 (19)	0.0151 (19)	0.009 (2)
C2	0.051 (3)	0.054 (3)	0.050 (3)	−0.001 (2)	0.021 (2)	0.001 (2)
C3	0.050 (3)	0.067 (3)	0.067 (3)	−0.014 (2)	0.021 (3)	−0.010 (3)
C4	0.039 (3)	0.085 (4)	0.072 (3)	0.002 (3)	0.022 (3)	0.004 (3)
C5	0.053 (3)	0.064 (3)	0.067 (3)	0.011 (2)	0.029 (3)	0.006 (3)
C6	0.046 (3)	0.054 (3)	0.053 (3)	0.005 (2)	0.023 (2)	0.009 (2)
C7	0.059 (3)	0.057 (3)	0.070 (3)	−0.006 (2)	0.027 (3)	−0.008 (2)
C8	0.109 (5)	0.099 (4)	0.077 (4)	0.020 (4)	0.028 (4)	−0.016 (3)
C9	0.138 (6)	0.067 (4)	0.106 (5)	0.019 (4)	0.061 (5)	0.013 (3)
C10	0.058 (3)	0.052 (3)	0.073 (3)	0.001 (2)	0.029 (3)	−0.007 (2)
C11	0.094 (5)	0.094 (4)	0.077 (4)	−0.022 (3)	0.032 (3)	−0.024 (3)
C12	0.109 (5)	0.063 (4)	0.107 (5)	−0.006 (3)	0.036 (4)	−0.003 (3)
C13	0.044 (3)	0.046 (2)	0.070 (3)	0.000 (2)	0.023 (2)	−0.007 (2)
C14	0.074 (4)	0.090 (4)	0.099 (4)	0.013 (3)	0.046 (3)	0.036 (4)
C15	0.048 (3)	0.085 (4)	0.086 (4)	−0.010 (3)	0.025 (3)	−0.021 (3)

Geometric parameters (Å, º)

N1—C13	1.281 (5)	C9—H9A	0.960
N1—C1	1.447 (5)	C9—H9B	0.960
N1—H1	0.870 (19)	C9—H9C	0.960
C1—C2	1.392 (6)	C10—C11	1.524 (7)
C1—C6	1.398 (6)	C10—C12	1.532 (7)
C2—C3	1.383 (6)	C10—H10	0.980
C2—C7	1.527 (6)	C11—H11A	0.960
C3—C4	1.370 (7)	C11—H11B	0.960
C3—H3	0.930	C11—H11C	0.960
C4—C5	1.385 (7)	C12—H12A	0.960
C4—H4	0.930	C12—H12B	0.960
C5—C6	1.385 (6)	C12—H12C	0.960
C5—H5	0.930	C13—C14	1.467 (7)
C6—C10	1.518 (6)	C13—C15	1.480 (6)
C7—C9	1.523 (7)	C14—H14A	0.960
C7—C8	1.524 (7)	C14—H14B	0.960
C7—H7	0.980	C14—H14C	0.960
C8—H8A	0.960	C15—H15A	0.960
C8—H8B	0.960	C15—H15B	0.960
C8—H8C	0.960	C15—H15C	0.960
C13—N1—C1	127.2 (4)	C7—C9—H9C	109.5
C13—N1—H1	115 (3)	H9A—C9—H9C	109.5
C1—N1—H1	117 (3)	H9B—C9—H9C	109.5
C2—C1—C6	123.1 (4)	C6—C10—C11	110.0 (4)
C2—C1—N1	118.8 (4)	C6—C10—C12	112.2 (4)
C6—C1—N1	118.0 (4)	C11—C10—C12	111.2 (5)
C3—C2—C1	116.8 (4)	C6—C10—H10	107.7
C3—C2—C7	120.5 (4)	C11—C10—H10	107.7
C1—C2—C7	122.7 (4)	C12—C10—H10	107.7
C4—C3—C2	121.9 (4)	C10—C11—H11A	109.5
C4—C3—H3	119.1	C10—C11—H11B	109.5
C2—C3—H3	119.1	H11A—C11—H11B	109.5
C3—C4—C5	120.1 (5)	C10—C11—H11C	109.5
C3—C4—H4	120.0	H11A—C11—H11C	109.5
C5—C4—H4	120.0	H11B—C11—H11C	109.5
C4—C5—C6	120.8 (5)	C10—C12—H12A	109.5
C4—C5—H5	119.6	C10—C12—H12B	109.5
C6—C5—H5	119.6	H12A—C12—H12B	109.5
C5—C6—C1	117.3 (4)	C10—C12—H12C	109.5
C5—C6—C10	119.6 (4)	H12A—C12—H12C	109.5
C1—C6—C10	123.1 (4)	H12B—C12—H12C	109.5
C9—C7—C8	111.3 (5)	N1—C13—C14	121.1 (4)
C9—C7—C2	110.7 (4)	N1—C13—C15	119.8 (4)
C8—C7—C2	111.8 (4)	C14—C13—C15	119.1 (5)
C9—C7—H7	107.6	C13—C14—H14A	109.5
C8—C7—H7	107.6	C13—C14—H14B	109.5
C2—C7—H7	107.6	H14A—C14—H14B	109.5
C7—C8—H8A	109.5	C13—C14—H14C	109.5
C7—C8—H8B	109.5	H14A—C14—H14C	109.5
H8A—C8—H8B	109.5	H14B—C14—H14C	109.5
C7—C8—H8C	109.5	C13—C15—H15A	109.5
H8A—C8—H8C	109.5	C13—C15—H15B	109.5
H8B—C8—H8C	109.5	H15A—C15—H15B	109.5
C7—C9—H9A	109.5	C13—C15—H15C	109.5
C7—C9—H9B	109.5	H15A—C15—H15C	109.5
H9A—C9—H9B	109.5	H15B—C15—H15C	109.5
C13—N1—C1—C2	−101.5 (5)	N1—C1—C6—C5	177.5 (4)
C13—N1—C1—C6	82.2 (6)	C2—C1—C6—C10	−177.1 (4)
C6—C1—C2—C3	−0.9 (6)	N1—C1—C6—C10	−1.0 (6)
N1—C1—C2—C3	−177.0 (4)	C3—C2—C7—C9	71.5 (6)
C6—C1—C2—C7	178.7 (4)	C1—C2—C7—C9	−108.1 (5)
N1—C1—C2—C7	2.6 (6)	C3—C2—C7—C8	−53.1 (6)
C1—C2—C3—C4	−0.5 (7)	C1—C2—C7—C8	127.2 (5)
C7—C2—C3—C4	179.9 (5)	C5—C6—C10—C11	−67.0 (6)
C2—C3—C4—C5	1.4 (8)	C1—C6—C10—C11	111.4 (5)
C3—C4—C5—C6	−1.0 (7)	C5—C6—C10—C12	57.4 (6)
C4—C5—C6—C1	−0.4 (7)	C1—C6—C10—C12	−124.2 (5)
C4—C5—C6—C10	178.2 (4)	C1—N1—C13—C14	5.5 (7)
C2—C1—C6—C5	1.3 (6)	C1—N1—C13—C15	−174.0 (4)