Bis­[4-(di­methyl­amino)­pyridinium] hexa­chloro­stannate(IV)

In the title compound, 4-(di­methyl­amino)­pyridine is proton­ated on the pyridine N atom. The N(CH₃)₂ moiety is twisted 4.4 (2)° from the pyridine-ring plane. The octahedral [SnCl₆]^2- anion is hydrogen bonded via trans-Cl atoms to pyridinium N atoms from two cations forming (C₇H₁₁N₂)₂[SnCl₆] structural units.

S1. Comment

Synthesis of extended metal halide systems could be achieved by the use of organic counter-cations as templating agents based on their shape and hydrogen-bonding capabilities. 4-(Dimethylamino)pyridine has two different N atoms susceptible to protonation, the pyridine and the amine. The pyridine N atom is the first choice for protonation in metal(II) halides (Halverson et al., 1990). The structural determination of the title compound, (I), was undertaken to examine catination of 4-(dimethylamino)pyridine in the presence of metal(IV). The structure consists of [SnCl₆]²⁻ bridging two (C₇H₁₁N₂)⁺ via hydrogen bonding through two pyridinium N atoms. Protonation occurs only on the pyridine N atom. Atom N1 is π bonded to the pyridine ring with a short N1—C1 bond of 1.335 (4) Å, comparable to the ring's nitrogen contacts [N2—C4 1.335 (5) Å and N2—C3 1.322 (6) Å]. The dimethylamine moiety is basically planar with the pyridine ring with only 4.4 (2)° twist from the plane of the ring. The pyridine N2 atom is hydrogen bonded to Cl1 [N2···Cl1 3.231 (5) Å]. The pyridinium cations are oriented so as to lie in the bc plane and form stacks parallel to the a axis.

S2. Experimental

Colourless transparent needles of (I) were found as an impurity amongst the main yellow product 4-(dimethylamino)pyridinium tetrachlorocuprate(II) (Haddad & Willett, 2000). The source of tin was apparently a corroding spatula. The reaction medium contained 5 mmol CuCl₂·2H₂O and 5 mmol of 4-(dimethylamino)pyridine in 20 ml 3 M HCl. The medium was heated at 348 K for 5 min. Yellow crystals of the copper(II) compound developed in two days together with few colourless crystals of the title compound of tin(IV).

S3. Refinement

All H atoms were located from a difference Fourier and were refined isotropically.

Computing details

Data collection: SMART (Bruker, 1996); cell refinement: SAINT (Bruker, 1996); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); software used to prepare material for publication: SHELXL97.

4-Dimethylaminopyridinium hexachlorostanate

Crystal data

(C7H11N2)2[SnCl6]	F(000) = 572
Mr = 577.74	Dx = 1.758 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 8.3328 (17) Å	Cell parameters from 4787 reflections
b = 11.680 (2) Å	θ = 2.0–28.2°
c = 11.724 (2) Å	µ = 1.91 mm^−1
β = 106.92 (3)°	T = 293 K
V = 1091.7 (4) Å^3	Parallelepiped, colourless
Z = 2	0.4 × 0.2 × 0.15 mm

Data collection

Siemens SMART 1000 diffractometer	1854 independent reflections
Radiation source: normal-focus sealed tube	1629 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.035
ω scans	θmax = 24.7°, θmin = 2.5°
Absorption correction: multi-scan (SADABS; Bruker, 1996)	h = −5→9
Tmin = 0.528, Tmax = 0.751	k = −13→12
5296 measured reflections	l = −13→13

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.025	All H-atom parameters refined
wR(F^2) = 0.065	w = 1/[σ^2(Fo^2) + (0.0309P)^2 + 0.2141P] where P = (Fo^2 + 2Fc^2)/3
S = 1.19	(Δ/σ)max = 0.001
1854 reflections	Δρmax = 0.32 e Å^−3
162 parameters	Δρmin = −0.34 e Å^−3
0 restraints	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0036 (6)

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	Occ. (<1)
Sn	0.5000	0.5000	0.0000	0.03134 (14)	0.989 (2)
Cl1	0.50471 (12)	0.63254 (7)	0.16141 (7)	0.0573 (3)
Cl2	0.58090 (12)	0.34573 (7)	0.14365 (7)	0.0564 (3)
Cl3	0.79094 (11)	0.54174 (10)	0.02168 (9)	0.0663 (3)
N1	0.9065 (3)	0.3422 (2)	0.5524 (2)	0.0489 (7)
C1	0.8195 (4)	0.4351 (3)	0.5633 (2)	0.0391 (7)
N2	0.6484 (4)	0.6321 (3)	0.5846 (4)	0.0643 (9)
C2	0.8081 (5)	0.4737 (3)	0.6747 (3)	0.0528 (9)
C4	0.6528 (5)	0.5979 (3)	0.4765 (4)	0.0578 (9)
C5	0.7331 (4)	0.5015 (3)	0.4624 (3)	0.0461 (8)
C3	0.7220 (5)	0.5714 (4)	0.6811 (4)	0.0623 (11)
C6	0.9064 (6)	0.2969 (4)	0.4362 (4)	0.0626 (11)
C7	1.0031 (7)	0.2747 (5)	0.6545 (5)	0.0742 (13)
H6A	0.945 (7)	0.351 (5)	0.397 (5)	0.13 (2)*
H4	0.593 (4)	0.645 (3)	0.417 (3)	0.056 (10)*
H2	0.870 (5)	0.432 (3)	0.737 (3)	0.066 (12)*
H7B	1.045 (6)	0.331 (5)	0.712 (4)	0.11 (2)*
H7A	0.924 (6)	0.244 (4)	0.686 (4)	0.094 (16)*
H5	0.731 (4)	0.483 (3)	0.388 (4)	0.050 (10)*
H6C	0.803 (6)	0.272 (4)	0.387 (4)	0.081 (13)*
H3	0.709 (5)	0.590 (4)	0.756 (4)	0.088 (13)*
H2'	0.594 (5)	0.691 (3)	0.589 (3)	0.068 (12)*
H6B	0.974 (7)	0.242 (5)	0.453 (5)	0.12 (2)*
H7C	1.098 (7)	0.249 (5)	0.634 (5)	0.13 (2)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Sn	0.0338 (2)	0.03110 (19)	0.02929 (18)	−0.00423 (11)	0.00937 (12)	0.00026 (10)
Cl1	0.0886 (7)	0.0444 (5)	0.0451 (5)	−0.0089 (4)	0.0290 (4)	−0.0106 (4)
Cl2	0.0752 (6)	0.0434 (5)	0.0438 (5)	−0.0007 (4)	0.0063 (4)	0.0124 (4)
Cl3	0.0401 (5)	0.0851 (7)	0.0745 (6)	−0.0151 (5)	0.0178 (4)	0.0008 (5)
N1	0.0483 (16)	0.0497 (17)	0.0455 (15)	0.0081 (13)	0.0084 (12)	0.0054 (12)
C1	0.0375 (16)	0.0409 (18)	0.0381 (16)	−0.0046 (13)	0.0098 (13)	0.0011 (13)
N2	0.055 (2)	0.0481 (19)	0.094 (3)	−0.0010 (15)	0.0294 (18)	−0.0173 (19)
C2	0.054 (2)	0.061 (2)	0.045 (2)	−0.0087 (18)	0.0160 (17)	−0.0010 (17)
C4	0.051 (2)	0.050 (2)	0.067 (2)	0.0057 (17)	0.0093 (18)	0.0063 (19)
C5	0.048 (2)	0.049 (2)	0.0391 (18)	0.0004 (15)	0.0090 (14)	0.0025 (15)
C3	0.061 (2)	0.074 (3)	0.059 (2)	−0.021 (2)	0.028 (2)	−0.025 (2)
C6	0.063 (3)	0.060 (3)	0.062 (2)	0.007 (2)	0.013 (2)	−0.013 (2)
C7	0.072 (3)	0.074 (3)	0.071 (3)	0.018 (2)	0.013 (3)	0.027 (3)

Geometric parameters (Å, º)

Sn—Cl3^i	2.4127 (10)	N1—C7	1.464 (5)
Sn—Cl3	2.4127 (10)	C1—C2	1.411 (4)
Sn—Cl2	2.4242 (9)	C1—C5	1.423 (4)
Sn—Cl2^i	2.4242 (9)	N2—C3	1.325 (5)
Sn—Cl1^i	2.4364 (8)	N2—C4	1.340 (5)
Sn—Cl1	2.4364 (8)	C2—C3	1.362 (6)
N1—C1	1.331 (4)	C4—C5	1.344 (5)
N1—C6	1.461 (5)
Cl3^i—Sn—Cl3	180.00 (5)	Cl2^i—Sn—Cl1	90.33 (3)
Cl3^i—Sn—Cl2	89.47 (4)	Cl1^i—Sn—Cl1	180.00 (2)
Cl3—Sn—Cl2	90.53 (4)	C1—N1—C6	122.2 (3)
Cl3^i—Sn—Cl2^i	90.53 (4)	C1—N1—C7	123.1 (3)
Cl3—Sn—Cl2^i	89.47 (4)	C6—N1—C7	114.7 (4)
Cl2—Sn—Cl2^i	180.00 (3)	N1—C1—C2	122.3 (3)
Cl3^i—Sn—Cl1^i	90.07 (4)	N1—C1—C5	121.5 (3)
Cl3—Sn—Cl1^i	89.93 (4)	C2—C1—C5	116.2 (3)
Cl2—Sn—Cl1^i	90.33 (3)	C3—N2—C4	121.0 (4)
Cl2^i—Sn—Cl1^i	89.67 (3)	C3—C2—C1	119.8 (4)
Cl3^i—Sn—Cl1	89.93 (4)	N2—C4—C5	121.2 (4)
Cl3—Sn—Cl1	90.07 (4)	C4—C5—C1	120.3 (3)
Cl2—Sn—Cl1	89.67 (3)	N2—C3—C2	121.4 (4)
C6—N1—C1—C2	174.7 (4)	C3—N2—C4—C5	−0.6 (6)
C7—N1—C1—C2	−2.5 (5)	N2—C4—C5—C1	−1.8 (5)
C6—N1—C1—C5	−5.6 (5)	N1—C1—C5—C4	−176.8 (3)
C7—N1—C1—C5	177.2 (4)	C2—C1—C5—C4	2.9 (5)
N1—C1—C2—C3	177.9 (3)	C4—N2—C3—C2	1.6 (6)
C5—C1—C2—C3	−1.8 (5)	C1—C2—C3—N2	−0.3 (6)

Symmetry code: (i) −x+1, −y+1, −z.