(-)-(S)-2-(Fluoro­di­phenyl­methyl)­pyrrolidinium chloride

The title compound, C₁₇H₁₉FN⁺·Cl^-, has an ionic structure, and cations and anions are linked into infinite chains by Cl...H-N-H...Cl hydrogen bonds. The absolute configuration (S) was confirmed.

S1. Comment

Homochiral amines are valuable as auxiliaries in enantioselective C—C bond-forming reactions (Morrison, 1983) and as chiral resolving agents (Parker, 1991). (-)-(S)-2-(Fluorodiphenylmethyl)pyrrolidine, (II), was prepared and studied (Bailey et al., 1997; Tavasli, 1999; O'Hagan et al., 2000) as a potential auxiliary in asymmetric alkylation reactions and as a chiral solvating agent for ¹H NMR analysis of the enantiomeric purity of chiral carboxylic acids and alcohols. In the course of this work, we studied the structure of the title compound, (I), the hydrochloride salt of (II).

The five-membered heterocycle adopts an envelope conformation; the N, C2, C4 and C5 atoms are coplanar within experimental error, with C3 deviating from their mean plane by 0.60 Å. The fluorodiphenylmethyl substituent is in an equatorial orientation. The conformation around the C1—C2 bond is staggered, with the F atom directed between N and C3. Cations and anions are linked by N—H···Cl hydrogen bonds into an infinite chain, spiralling around the 2₁ axis (x, 3/4 − y, 1/2 − z).

Although the F—C1—C2—N torsion angle of −63.9 (1)° brings the H2N atom close to the F atom, the F···H2N distance of 2.53 (2) Å and a narrow N—H—F angle of 104 (2)° are indicative of a slightly shortened van der Waals contact (Howard et al., 1996) rather than an intramolecular hydrogen bond. Genuine intermolecular N—H···F—C bonds (which are extremely rare) display H···F distances from 2.10 to 2.33 Å (Dunitz & Taylor, 1997) and N—H···F arrangements much closer to linear.

S2. Experimental

Enantiomerically pure (S)-2-(fluorodiphenylmethyl)pyrrolidine, (II), was prepared (from the corresponding oxazolidinone) and characterized spectroscopically by O'Hagan et al. (2000). Optical rotation was measured on an Optical Activity Ltd AA-10 automatic polarimeter, [α]_D²⁵ = −0.81° cm² g⁻¹ (MeOH, c 7.4). Salt (I) formed readily as a white precipitate on bubbling gaseous HCl through the solution of (II) in diethyl ether (Tavasli, 1999). Crystals of X-ray quality were obtained by recrystallization from 2-propanol.

S3. Refinement

2337 symmetrically independent reflections and 1670 Friedel equivalents were measured [respectively, 2252 and 1592 with I>2σ(I)]. All H atoms were refined in isotropic approximation; bond distances Csp²—H 0.93 (2)–1.01 (2) Å and Csp³—H 0.94 (2)–0.98 (2) Å.

Computing details

Data collection: SMART (Bruker, 1999); cell refinement: SMART; data reduction: SAINT (Bruker, 1999); program(s) used to solve structure: SHELXTL (Bruker, 1997); program(s) used to refine structure: SHELXTL; software used to prepare material for publication: SHELXTL.

(-)-(S)-2-(Fluorodiphenylmethyl)pyrrolidinium chloride

Crystal data

C17H19FN^+·Cl^−	Dx = 1.282 Mg m^−3
Mr = 291.78	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, P212121	Cell parameters from 840 reflections
a = 7.415 (3) Å	θ = 12.0–26.4°
b = 8.353 (4) Å	µ = 0.25 mm^−1
c = 24.406 (10) Å	T = 120 K
V = 1511.6 (11) Å^3	Plate, colourless
Z = 4	0.58 × 0.45 × 0.14 mm
F(000) = 616

Data collection

SMART 1K CCD area-detector diffractometer	4007 independent reflections
Radiation source: fine-focus sealed tube	3844 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.020
Detector resolution: 8 pixels mm^-1	θmax = 29.1°, θmin = 1.7°
ω scans	h = −9→10
Absorption correction: multi-scan (SADABS; Sheldrick, 1998); Rint = 0.030 before correction	k = −11→10
Tmin = 0.847, Tmax = 0.962	l = −33→33
14327 measured reflections

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.027	All H-atom parameters refined
wR(F^2) = 0.067	Calculated w = 1/[σ^2(Fo^2) + (0.0417P)^2 + 0.1226P] where P = (Fo^2 + 2Fc^2)/3
S = 1.08	(Δ/σ)max = 0.003
4007 reflections	Δρmax = 0.29 e Å^−3
257 parameters	Δρmin = −0.19 e Å^−3
0 restraints	Absolute structure: Flack (1983)
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: −0.01 (4)

Special details

Experimental. The data collection nominally covered over a hemisphere of reciprocal space, by a combination of four sets of ω scans; each set at different ϕ and/or 2θ angles and each scan (15 sec exposure) covering 0.3° in ω. Crystal decay was monitored by repeating 50 initial frames at the end of data collection and comparing duplicate reflections. Crystal to detector distance 4.51 cm.

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.

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

	x	y	z	Uiso*/Ueq
Cl	0.27784 (4)	0.92920 (3)	0.517928 (12)	0.02246 (7)
F	0.09308 (9)	0.41100 (9)	0.38753 (3)	0.02327 (15)
N	0.19167 (13)	0.58321 (12)	0.48509 (4)	0.01781 (17)
H1N	0.215 (2)	0.688 (2)	0.4873 (7)	0.028 (4)*
H2N	0.078 (2)	0.572 (2)	0.4751 (7)	0.027 (4)*
C1	0.25370 (15)	0.50414 (14)	0.38787 (4)	0.0178 (2)
C2	0.32369 (15)	0.50221 (14)	0.44705 (4)	0.0169 (2)
H2	0.4333 (19)	0.5598 (17)	0.4501 (5)	0.014 (3)*
C3	0.35215 (18)	0.33836 (14)	0.47338 (5)	0.0216 (2)
H31	0.461 (2)	0.291 (2)	0.4624 (7)	0.034 (4)*
H32	0.252 (2)	0.2678 (18)	0.4651 (6)	0.020 (3)*
C4	0.35491 (18)	0.37784 (15)	0.53500 (5)	0.0231 (2)
H41	0.474 (2)	0.4165 (19)	0.5458 (6)	0.023 (4)*
H42	0.333 (2)	0.288 (2)	0.5586 (7)	0.031 (4)*
C5	0.21312 (18)	0.50914 (14)	0.54142 (4)	0.0216 (2)
H51	0.249 (2)	0.588 (2)	0.5665 (7)	0.034 (4)*
H52	0.097 (2)	0.472 (2)	0.5522 (6)	0.029 (4)*
C11	0.38492 (16)	0.42449 (15)	0.34784 (4)	0.0203 (2)
C12	0.56983 (17)	0.41412 (17)	0.35809 (5)	0.0249 (2)
H12	0.621 (2)	0.4567 (18)	0.3914 (6)	0.023 (4)*
C13	0.68421 (18)	0.33778 (18)	0.32065 (5)	0.0293 (3)
H13	0.815 (3)	0.328 (2)	0.3287 (7)	0.034 (4)*
C14	0.6141 (2)	0.27055 (17)	0.27289 (5)	0.0304 (3)
H14	0.688 (2)	0.212 (2)	0.2487 (7)	0.030 (4)*
C15	0.4310 (2)	0.28317 (18)	0.26219 (5)	0.0308 (3)
H15	0.378 (2)	0.239 (2)	0.2276 (7)	0.035 (4)*
C16	0.31605 (18)	0.36049 (15)	0.29898 (5)	0.0248 (2)
H16	0.190 (2)	0.3690 (18)	0.2907 (6)	0.022 (4)*
C21	0.20488 (17)	0.67430 (13)	0.36953 (4)	0.0196 (2)
C22	0.33566 (17)	0.79428 (15)	0.37116 (5)	0.0235 (2)
H22	0.462 (2)	0.768 (2)	0.3830 (7)	0.032 (4)*
C23	0.2929 (2)	0.95081 (15)	0.35549 (5)	0.0298 (3)
H23	0.376 (3)	1.034 (2)	0.3570 (8)	0.041 (5)*
C24	0.1195 (2)	0.98682 (17)	0.33770 (5)	0.0313 (3)
H24	0.082 (3)	1.093 (3)	0.3267 (8)	0.047 (5)*
C25	−0.0101 (2)	0.86835 (18)	0.33570 (6)	0.0311 (3)
H25	−0.138 (3)	0.891 (2)	0.3237 (7)	0.039 (5)*
C26	0.03071 (18)	0.71145 (16)	0.35168 (5)	0.0261 (2)
H26	−0.060 (2)	0.6283 (19)	0.3521 (7)	0.027 (4)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cl	0.01711 (12)	0.01938 (12)	0.03091 (13)	0.00004 (10)	0.00256 (10)	−0.00270 (11)
F	0.0205 (3)	0.0238 (4)	0.0255 (3)	−0.0042 (3)	−0.0017 (3)	−0.0005 (3)
N	0.0170 (4)	0.0169 (4)	0.0195 (4)	0.0007 (4)	0.0006 (3)	0.0002 (4)
C1	0.0173 (5)	0.0171 (5)	0.0191 (4)	−0.0034 (4)	−0.0007 (4)	0.0001 (4)
C2	0.0152 (5)	0.0177 (5)	0.0177 (4)	−0.0002 (4)	0.0007 (4)	−0.0001 (4)
C3	0.0245 (6)	0.0174 (5)	0.0228 (5)	0.0035 (4)	0.0011 (4)	0.0015 (4)
C4	0.0244 (6)	0.0234 (6)	0.0216 (5)	0.0019 (5)	0.0000 (4)	0.0046 (4)
C5	0.0244 (6)	0.0232 (5)	0.0174 (4)	0.0000 (5)	0.0022 (4)	0.0012 (4)
C11	0.0257 (5)	0.0171 (5)	0.0180 (5)	−0.0007 (5)	0.0014 (4)	0.0002 (4)
C12	0.0260 (6)	0.0286 (6)	0.0201 (5)	−0.0018 (5)	0.0019 (4)	−0.0045 (5)
C13	0.0264 (7)	0.0352 (7)	0.0261 (6)	0.0021 (5)	0.0042 (5)	−0.0031 (5)
C14	0.0393 (7)	0.0282 (6)	0.0237 (6)	0.0039 (6)	0.0075 (5)	−0.0034 (5)
C15	0.0427 (8)	0.0305 (6)	0.0191 (5)	−0.0010 (6)	−0.0006 (5)	−0.0046 (5)
C16	0.0291 (7)	0.0244 (6)	0.0208 (5)	−0.0008 (5)	−0.0024 (4)	−0.0011 (4)
C21	0.0235 (5)	0.0193 (5)	0.0161 (5)	0.0005 (4)	0.0005 (4)	0.0006 (4)
C22	0.0253 (6)	0.0225 (6)	0.0227 (5)	−0.0032 (5)	−0.0033 (4)	0.0024 (4)
C23	0.0404 (7)	0.0208 (6)	0.0281 (6)	−0.0057 (6)	−0.0027 (5)	0.0030 (4)
C24	0.0425 (8)	0.0227 (6)	0.0287 (6)	0.0057 (6)	0.0010 (6)	0.0056 (5)
C25	0.0297 (7)	0.0325 (7)	0.0311 (6)	0.0083 (6)	−0.0007 (5)	0.0065 (5)
C26	0.0229 (6)	0.0277 (6)	0.0277 (6)	0.0015 (5)	−0.0006 (5)	0.0031 (5)

Geometric parameters (Å, º)

F—C1	1.4226 (13)	C12—C13	1.4003 (18)
N—C2	1.5093 (15)	C12—H12	0.965 (16)
N—C5	1.5159 (15)	C13—C14	1.394 (2)
N—H1N	0.897 (18)	C13—H13	0.993 (19)
N—H2N	0.886 (17)	C14—C15	1.387 (2)
C1—C11	1.5310 (16)	C14—H14	0.942 (17)
C1—C21	1.5335 (17)	C15—C16	1.3964 (19)
C1—C2	1.5349 (15)	C15—H15	1.000 (18)
C2—C3	1.5267 (17)	C16—H16	0.956 (16)
C2—H2	0.948 (14)	C21—C22	1.3951 (17)
C3—C4	1.5398 (18)	C21—C26	1.3979 (18)
C3—H31	0.936 (18)	C22—C23	1.3987 (19)
C3—H32	0.972 (15)	C22—H22	1.004 (17)
C4—C5	1.5274 (18)	C23—C24	1.390 (2)
C4—H41	0.975 (16)	C23—H23	0.93 (2)
C4—H42	0.956 (17)	C24—C25	1.380 (2)
C5—H51	0.940 (18)	C24—H24	0.97 (2)
C5—H52	0.951 (18)	C25—C26	1.4005 (19)
C11—C12	1.3964 (18)	C25—H25	1.008 (19)
C11—C16	1.4031 (17)	C26—H26	0.969 (17)
C2—N—C5	107.87 (9)	C12—C11—C16	119.08 (11)
C2—N—H1N	110.6 (11)	C12—C11—C1	122.45 (10)
C5—N—H1N	109.0 (10)	C16—C11—C1	118.47 (11)
C2—N—H2N	113.9 (11)	C11—C12—C13	120.40 (12)
C5—N—H2N	108.0 (11)	C11—C12—H12	121.1 (9)
H1N—N—H2N	107.4 (15)	C13—C12—H12	118.4 (9)
F—C1—C11	106.90 (9)	C14—C13—C12	120.21 (13)
F—C1—C21	107.91 (9)	C14—C13—H13	119.6 (10)
C11—C1—C21	111.50 (9)	C12—C13—H13	120.1 (10)
F—C1—C2	106.43 (8)	C15—C14—C13	119.46 (12)
C11—C1—C2	112.40 (9)	C15—C14—H14	119.5 (10)
C21—C1—C2	111.36 (9)	C13—C14—H14	121.0 (10)
N—C2—C3	103.45 (9)	C14—C15—C16	120.78 (12)
N—C2—C1	110.78 (9)	C14—C15—H15	120.9 (10)
C3—C2—C1	116.89 (10)	C16—C15—H15	118.3 (10)
N—C2—H2	106.3 (8)	C15—C16—C11	120.03 (12)
C3—C2—H2	107.6 (8)	C15—C16—H16	119.5 (9)
C1—C2—H2	111.1 (8)	C11—C16—H16	120.4 (9)
C2—C3—C4	102.77 (9)	C22—C21—C26	119.45 (11)
C2—C3—H31	112.3 (11)	C22—C21—C1	119.56 (11)
C4—C3—H31	111.1 (11)	C26—C21—C1	120.98 (11)
C2—C3—H32	110.5 (9)	C21—C22—C23	120.41 (12)
C4—C3—H32	110.1 (9)	C21—C22—H22	120.0 (10)
H31—C3—H32	110.0 (13)	C23—C22—H22	119.6 (10)
C5—C4—C3	104.17 (9)	C24—C23—C22	119.83 (13)
C5—C4—H41	110.9 (9)	C24—C23—H23	117.6 (11)
C3—C4—H41	110.4 (9)	C22—C23—H23	122.6 (12)
C5—C4—H42	112.6 (10)	C25—C24—C23	120.00 (13)
C3—C4—H42	114.7 (10)	C25—C24—H24	116.7 (12)
H41—C4—H42	104.2 (14)	C23—C24—H24	123.3 (12)
N—C5—C4	105.80 (9)	C24—C25—C26	120.70 (13)
N—C5—H51	109.5 (10)	C24—C25—H25	121.8 (11)
C4—C5—H51	111.9 (11)	C26—C25—H25	117.5 (11)
N—C5—H52	106.9 (10)	C21—C26—C25	119.61 (13)
C4—C5—H52	114.4 (10)	C21—C26—H26	118.8 (9)
H51—C5—H52	108.1 (14)	C25—C26—H26	121.6 (9)
C5—N—C2—C3	25.78 (11)	F—C1—C11—C12	−141.65 (12)
C5—N—C2—C1	151.81 (9)	C21—C1—C11—C12	100.63 (14)
F—C1—C2—N	−63.89 (11)	C2—C1—C11—C12	−25.23 (16)
C11—C1—C2—N	179.41 (9)	F—C1—C11—C16	38.68 (14)
C21—C1—C2—N	53.47 (12)	C21—C1—C11—C16	−79.04 (13)
F—C1—C2—C3	54.23 (12)	C2—C1—C11—C16	155.10 (11)
C11—C1—C2—C3	−62.47 (13)	F—C1—C21—C22	174.06 (10)
C21—C1—C2—C3	171.60 (10)	C11—C1—C21—C22	−68.83 (13)
N—C2—C3—C4	−38.77 (11)	C2—C1—C21—C22	57.60 (14)
C1—C2—C3—C4	−160.79 (10)	F—C1—C21—C26	−5.33 (14)
C2—C3—C4—C5	37.53 (13)	C11—C1—C21—C26	111.78 (12)
C2—N—C5—C4	−2.40 (12)	C2—C1—C21—C26	−121.79 (11)
C3—C4—C5—N	−21.77 (13)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N—H1N···Cl	0.897 (18)	2.196 (17)	3.0664 (17)	163.4 (14)
N—H2N···Cl^i	0.886 (17)	2.229 (17)	3.0712 (16)	158.9 (14)

Symmetry code: (i) x−1/2, −y+3/2, −z+1.