Dichlorobis(pyridine-κN)bis(3,3,3-trifluoropropyl-κC¹)tin(IV)

In the title compound, [Sn(C₃H₄F₃)₂Cl₂(C₅H₅N)₂], the Sn atom lies on an inversion centre and is octahedrally coordinated by two Cl atoms, two tri­fluoro­propyl groups and two N atoms in an all-trans configuration. The electronegative tri­fluoro­propyl groups increase the electrophilic properties of the Sn atom, and the Sn—Cl and Sn—N bonds are shortened in comparison with those reported for analogous compounds.

S1. Comment

Organotin compounds, which show a great variety of applications in organic (Jousseaume & Pereyre, 1998) and industrial (Evans, 1998) chemistry, have been mainly developed with simple organic residues such as methyl, butyl, octyl or phenyl groups, the corresponding raw materials being cheap and easily available. It is therefore of interest to study the influence of other organic groups on the chemical and physico-chemical properties of the corresponding organotin compounds, in order to change or improve these properties and to establish structure-reactivity relationships.

The introduction onto an alkyl group linked to a Sn of electronegative elements, such as oxygen or halogens, lowers the stability of the corresponding organotin compounds (Davies, 1997; Jousseaume et al., 1992), which can be expressed by a lengthening of the corresponding Sn—C bond (White & Giordano, 2001), and should increase the electrophilic properties of the metal. We have thus been interested in (3,3,3-trifluoropropyl)tin compounds (Franc et al., 2000), where an electronegative trifluoromethyl group is situated in a β position relative to the Sn. However, dichlorobis(3,3,3-trifluoropropyl)tin, unlike most dichlorodiorganotin compounds, is liquid at room temperature. The title compound, (I), with the addition of pyridine ligands, has thus been prepared and its crystal structure is presented here. \sch

In this compound, which is a discrete 1:2 adduct An adduct of what?, no intermolecular Sn—Cl or Sn—N contacts shorter than 4 Å are present in the unit cell. The Sn atom, which is at a centre of symmetry, is six-coordinate and shows an octahedral geometry. The ligands are in an all-trans configuration.

A comparison of the Sn—C bond with those of analogous compounds with methyl (Aslanov et al., 1978) or ethyl groups (Casas et al., 2000), i.e. dichlorodimethylbis(pyridine-N)tin and dichlorodiethylbis(pyridine-N)tin, shows a lengthening of 0.01 Å, while the Sn—N and Sn—Cl bonds are shortened by 0.03 and 0.05 Å, and 0.04 and 0.06 Å, respectively. These findings can be interpreted by an increase of the electrophilic properties of the Sn atom due to the presence of three F atoms at the end of the carbon chain.

The dihedral angle between the C—C bond and the Sn—Cl bond is the same (127°) as in the corresponding diethyl derivative. The pyridine ring is more tilted with respect to the N—Sn—Cl plane, by 31° instead of 22°, which decreases possible H(C16)—Cl interactions as the interatomic distance increases from 1.86 to 2.90 Å.

Crystal cohesion is assumed to occur through very weak van der Waals interactions. In addition, there is no superposition of aromatic pyridine molecules.

Table 2. Comparison of bond lengths in R₂SnCl₂(pyridine)₂ complexes

S2. Experimental

The title complex was prepared by the addition of a solution of pyridine in chloroform to a solution of dichlorobis(3,3,3-trifluoropropyl)tin in the same solvent. After 10 d, crystals of (I) suitable for X-ray analysis were obtained.

S3. Refinement

All H atoms were located on difference Fourier syntheses but they were included in the refinement using a riding model approximation, with isotropic displacement factors fixed at 1.2U_eq of the parent atom and C—H distances of 0.97 Å for CH₂ and 0.93 Å for C₆H₅.

Computing details

Data collection: KappaCCD Reference Manual (Nonius, 1998); data reduction: DENZO-SMN (Otwinowski & Minor, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPIII (Burnett & Johnson, 1996); software used to prepare material for publication: SHELXL97.

Figures

Fig. 1. A view of the molecule of (I), showing the atom-numbering system. Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as small spheres of arbitrary radii.

Dichlorobis(pyridine-κN)bis(3,3,3-trifluoropropyl-κC¹)tin(IV)

Crystal data

[Sn(C3H4F3)2(C5H5N)2Cl2]	F(000) = 532
Mr = 541.92	Dx = 1.773 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71069 Å
Hall symbol: -P 2ybc	Cell parameters from 4606 reflections
a = 10.4684 (4) Å	θ = 3.4–27.5°
b = 10.3551 (3) Å	µ = 1.58 mm^−1
c = 9.4337 (3) Å	T = 293 K
β = 96.939 (2)°	Needle, colourless
V = 1015.14 (6) Å^3	0.33 × 0.09 × 0.08 mm
Z = 2

Data collection

Nonius KappaCCD area-detector diffractometer	1648 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.045
Graphite monochromator	θmax = 27.5°, θmin = 3.4°
ω scans	h = −13→13
4606 measured reflections	k = −13→13
2314 independent reflections	l = −12→12

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)] = 0.039	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.085	H-atom parameters constrained
S = 0.99	w = 1/[σ^2(Fo^2) + (0.0441P)^2] where P = (Fo^2 + 2Fc^2)/3
2246 reflections	(Δ/σ)max < 0.001
124 parameters	Δρmax = 0.70 e Å^−3
0 restraints	Δρmin = −0.67 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
Sn1	0.0000	0.0000	0.0000	0.02684 (13)
Cl2	−0.00700 (8)	−0.23863 (7)	−0.06075 (10)	0.0414 (2)
C3	0.1583 (3)	0.0268 (3)	−0.1242 (4)	0.0354 (7)
H3A	0.1846	−0.0573	−0.1557	0.042*
H3B	0.1277	0.0763	−0.2088	0.042*
C4	0.2745 (3)	0.0936 (4)	−0.0487 (4)	0.0447 (8)
H4A	0.2474	0.1744	−0.0096	0.054*
H4B	0.3104	0.0401	0.0308	0.054*
C5	0.3767 (3)	0.1211 (4)	−0.1400 (4)	0.0461 (9)
F6	0.3388 (3)	0.1981 (3)	−0.2488 (3)	0.0849 (8)
F7	0.4795 (2)	0.1764 (3)	−0.0687 (3)	0.0819 (8)
F8	0.4211 (3)	0.0159 (2)	−0.1997 (4)	0.0820 (10)
N11	0.1432 (3)	−0.0433 (3)	0.2082 (3)	0.0321 (6)
C12	0.1443 (4)	0.0301 (3)	0.3242 (4)	0.0421 (9)
H12	0.0856	0.0976	0.3227	0.051*
C13	0.2284 (5)	0.0106 (3)	0.4465 (5)	0.0509 (11)
H13	0.2249	0.0621	0.5268	0.061*
C14	0.3178 (4)	−0.0870 (4)	0.4466 (4)	0.0530 (10)
H14	0.3788	−0.0997	0.5255	0.064*
C15	0.3157 (3)	−0.1646 (4)	0.3301 (4)	0.0480 (9)
H15	0.3734	−0.2328	0.3298	0.058*
C16	0.2274 (3)	−0.1411 (3)	0.2128 (3)	0.0392 (8)
H16	0.2260	−0.1951	0.1338	0.047*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Sn1	0.02396 (17)	0.02785 (19)	0.0290 (2)	−0.00012 (10)	0.00447 (11)	−0.00111 (11)
Cl2	0.0444 (5)	0.0301 (4)	0.0505 (5)	−0.0008 (3)	0.0087 (3)	−0.0057 (4)
C3	0.0294 (17)	0.0450 (18)	0.0329 (18)	−0.0048 (13)	0.0090 (13)	−0.0009 (14)
C4	0.0302 (19)	0.063 (2)	0.0408 (19)	−0.0118 (16)	0.0051 (14)	−0.0028 (17)
C5	0.036 (2)	0.057 (2)	0.046 (2)	−0.0119 (16)	0.0033 (15)	−0.0005 (18)
F6	0.0705 (18)	0.108 (2)	0.0747 (17)	−0.0221 (15)	0.0043 (13)	0.0432 (16)
F7	0.0457 (14)	0.129 (2)	0.0705 (16)	−0.0432 (15)	0.0051 (11)	−0.0144 (17)
F8	0.0563 (18)	0.086 (2)	0.112 (3)	−0.0079 (12)	0.0438 (17)	−0.0251 (15)
N11	0.0308 (15)	0.0362 (13)	0.0296 (15)	0.0003 (12)	0.0047 (11)	0.0031 (12)
C12	0.051 (2)	0.0378 (17)	0.036 (2)	0.0064 (15)	0.0001 (16)	−0.0015 (15)
C13	0.060 (3)	0.051 (2)	0.038 (2)	−0.0007 (17)	−0.0071 (19)	−0.0064 (16)
C14	0.052 (2)	0.057 (2)	0.045 (2)	−0.0028 (19)	−0.0146 (17)	0.0096 (18)
C15	0.035 (2)	0.053 (2)	0.055 (2)	0.0101 (16)	0.0045 (16)	0.0149 (18)
C16	0.040 (2)	0.0405 (18)	0.0379 (18)	0.0049 (15)	0.0064 (14)	0.0016 (15)

Geometric parameters (Å, º)

Sn1—C3	2.160 (3)	N11—C12	1.331 (5)
Sn1—N11	2.365 (3)	N11—C16	1.340 (4)
Sn1—Cl2	2.5357 (7)	C12—C13	1.379 (5)
C3—C4	1.502 (4)	C12—H12	0.9300
C3—H3A	0.9700	C13—C14	1.377 (6)
C3—H3B	0.9700	C13—H13	0.9300
C4—C5	1.479 (5)	C14—C15	1.359 (5)
C4—H4A	0.9700	C14—H14	0.9300
C4—H4B	0.9700	C15—C16	1.375 (5)
C5—F6	1.322 (4)	C15—H15	0.9300
C5—F7	1.328 (4)	C16—H16	0.9300
C5—F8	1.336 (4)
C3—Sn1—N11^i	88.61 (11)	F7—C5—C4	112.7 (3)
C3—Sn1—N11	91.39 (11)	F8—C5—C4	113.6 (3)
C3—Sn1—Cl2	90.32 (9)	C12—N11—C16	117.7 (3)
N11—Sn1—Cl2	90.07 (7)	C12—N11—Sn1	121.1 (2)
C4—C3—Sn1	115.6 (2)	C16—N11—Sn1	121.2 (2)
C4—C3—H3A	108.4	N11—C12—C13	123.1 (3)
Sn1—C3—H3A	108.4	N11—C12—H12	118.5
C4—C3—H3B	108.4	C13—C12—H12	118.5
Sn1—C3—H3B	108.4	C14—C13—C12	118.2 (4)
H3A—C3—H3B	107.4	C14—C13—H13	120.9
C5—C4—C3	114.4 (3)	C12—C13—H13	120.9
C5—C4—H4A	108.7	C15—C14—C13	119.3 (3)
C3—C4—H4A	108.7	C15—C14—H14	120.4
C5—C4—H4B	108.7	C13—C14—H14	120.4
C3—C4—H4B	108.7	C14—C15—C16	119.4 (3)
H4A—C4—H4B	107.6	C14—C15—H15	120.3
F6—C5—F7	106.4 (3)	C16—C15—H15	120.3
F6—C5—F8	104.6 (3)	N11—C16—C15	122.3 (3)
F7—C5—F8	105.3 (3)	N11—C16—H16	118.8
F6—C5—C4	113.5 (3)	C15—C16—H16	118.8

Symmetry code: (i) −x, −y, −z.