Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536801002008/bt6013sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536801002008/bt6013Isup2.hkl |
CCDC reference: 159841
The salt (I) was prepared as described (Hanke & Jutz, 1980) for the perchlorate analogue, except that NaBF4 was used instead of NaClO4. Crystallization from ethanol gave (I) as orange spars, m.p. 469.0–472.5 K. 1H NMR (200 MHz, DMSO-d6): δ = 3.10, 3.14 (each s, 6H, NMe), 6.07 (d, J = 12.2 Hz, 2H, C2—H+C4—H), 6.95 (d, J = 12.2 Hz, 2H, C1—H+C5—H), 7.28 (d, Jobs = 5.0 Hz, 2H, pyridine β-H) and 8.71 (d, Jobs = 5.0 Hz, 2H, pyridine α-H); (200 MHz, CDCl3): δ = 3.19, 3.24 (each s, 6H, NMe), 6.28 (d, J = 12.2 Hz, 2H, C2—H+C4—H), 6.76 (d, J = 12.2 Hz, 2H, C1—H+C5—H), 7.26 (obscured by solvent peak, pyridine β-H), 7.34 (d, Jobs = 5.0 Hz, 1H, pyridine β-H), 8.71 (d, Jobs = 5.0 Hz, 1H, pyridine α-H) and 8.79 (d, Jobs = 5.0 Hz, 1H, pyridine α-H).
H atoms were treated as riding atoms with C—H distances of 0.93 and 0.96 Å. All four methyl groups were allowed to rotate about their local threefold axis. The tetrafluoroborate ion is disordered by rotation about the B1—F1 bond over two sites with unequal occupancies [0.918 (5) and 0.082 (5)]. In the minor orientation, the three F atoms (F12, F13 and F14) were only allowed an overall isotropic vibration parameter; the geometry at B1 was restrained to be tetrahedral and an overall B—F distance was refined using a combination of DFIX and free-variable controls.
Data collection: CAD-4 Software (Enraf-Nonius, 1992); cell refinement: SET4 and CELDIM (Enraf-Nonius, 1992); data reduction: HELENA in PLATON (Spek, 2001); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPII (Johnson, 1976) and PLATON (Spek, 2001); software used to prepare material for publication: SHELXL97.
Fig. 1. A view of (I) with the atomic numbering scheme. Displacement ellipsoids are drawn at the 30% probability level. Only the major component of the disordered tetrafluoroborate anion is shown |
C14H20N3+·BF4− | F(000) = 664 |
Mr = 317.14 | Dx = 1.315 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
a = 7.982 (2) Å | Cell parameters from 25 reflections |
b = 10.492 (2) Å | θ = 9.1–11.2° |
c = 19.950 (3) Å | µ = 0.11 mm−1 |
β = 106.578 (19)° | T = 293 K |
V = 1601.3 (6) Å3 | Needle, orange |
Z = 4 | 0.38 × 0.34 × 0.20 mm |
Nonius CAD-4 diffractometer | Rint = 0.018 |
Radiation source: fine-focus sealed X-ray tube | θmax = 27.0°, θmin = 2.1° |
Graphite monochromator | h = 0→10 |
θ/2θ scans | k = −13→0 |
3931 measured reflections | l = −25→24 |
3482 independent reflections | 3 standard reflections every 120 min |
2306 reflections with I > 2σ(I) | intensity decay: none |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.057 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.195 | H-atom parameters constrained |
S = 1.04 | w = 1/[σ2(Fo2) + (0.0995P)2 + 0.6393P] where P = (Fo2 + 2Fc2)/3 |
3482 reflections | (Δ/σ)max = 0.009 |
215 parameters | Δρmax = 0.36 e Å−3 |
13 restraints | Δρmin = −0.30 e Å−3 |
C14H20N3+·BF4− | V = 1601.3 (6) Å3 |
Mr = 317.14 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 7.982 (2) Å | µ = 0.11 mm−1 |
b = 10.492 (2) Å | T = 293 K |
c = 19.950 (3) Å | 0.38 × 0.34 × 0.20 mm |
β = 106.578 (19)° |
Nonius CAD-4 diffractometer | Rint = 0.018 |
3931 measured reflections | 3 standard reflections every 120 min |
3482 independent reflections | intensity decay: none |
2306 reflections with I > 2σ(I) |
R[F2 > 2σ(F2)] = 0.057 | 13 restraints |
wR(F2) = 0.195 | H-atom parameters constrained |
S = 1.04 | Δρmax = 0.36 e Å−3 |
3482 reflections | Δρmin = −0.30 e Å−3 |
215 parameters |
Geometry. Mean-plane data from the final SHELXL97 refinement run:- Least-squares planes (x,y,z in crystal coordinates) and deviations from them (* indicates atom used to define plane) 7.4886 (0.0031) x + 2.3601 (0.0157) y - 0.3101 (0.0396) z = 1.9387 (0.0012) * -0.0594 (0.0013) N1 * 0.0288 (0.0015) C1 * 0.0258 (0.0018) C2 * 0.0054 (0.0016) C3 * 0.0662 (0.0018) C4 * -0.0425 (0.0015) C5 * -0.0244 (0.0013) N2 Rms deviation of fitted atoms = 0.0411 5.9988 (0.0056) x - 6.0519 (0.0072) y - 10.3986 (0.0124) z = 0.3414 (0.0029) Angle to previous plane (with approximate e.s.d.) = 60.58 (9) * 0.0160 (0.0013) C3 * 0.0163 (0.0018) N31 * -0.0035 (0.0018) C32 * -0.0108 (0.0018) C33 * -0.0040 (0.0017) C34 * -0.0163 (0.0018) C35 * 0.0024 (0.0017) C36 Rms deviation of fitted atoms = 0.0116 ####################################################################### 7.4886 (0.0031) x + 2.3601 (0.0157) y - 0.3101 (0.0396) z = 1.9387 (0.0012) * -0.0594 (0.0013) N1 * 0.0288 (0.0015) C1 * 0.0258 (0.0018) C2 * 0.0054 (0.0016) C3 * 0.0662 (0.0018) C4 * -0.0425 (0.0015) C5 * -0.0244 (0.0013) N2 Rms deviation of fitted atoms = 0.0411 7.5916 (0.0045) x + 2.7191 (0.0167) y - 2.1992 (0.0288) z = 1.9475 (0.0043) Angle to previous plane (with approximate e.s.d.) = 5.83 (12) * 0.0048 (0.0018) N1 * -0.0015 (0.0006) C11 * -0.0015 (0.0006) C12 * -0.0018 (0.0007) C1 Rms deviation of fitted atoms = 0.0028 ######################################################################### 7.4886 (0.0031) x + 2.3601 (0.0157) y - 0.3101 (0.0396) z = 1.9387 (0.0012) * -0.0594 (0.0013) N1 * 0.0288 (0.0015) C1 * 0.0258 (0.0018) C2 * 0.0054 (0.0016) C3 * 0.0662 (0.0018) C4 * -0.0425 (0.0015) C5 * -0.0244 (0.0013) N2 Rms deviation of fitted atoms = 0.0411 7.2706 (0.0059) x + 1.9358 (0.0159) y + 1.8738 (0.0352) z = 2.0549 (0.0061) Angle to previous plane (with approximate e.s.d.) = 6.69 (17) * -0.0086 (0.0019) N2 * 0.0027 (0.0006) C21 * 0.0027 (0.0006) C22 * 0.0032 (0.0007) C5 Rms deviation of fitted atoms = 0.0050 |
x | y | z | Uiso*/Ueq | Occ. (<1) | |
N1 | 0.3035 (2) | −0.17387 (18) | −0.05512 (9) | 0.0492 (5) | |
N2 | 0.1476 (2) | 0.36189 (17) | 0.14546 (9) | 0.0498 (5) | |
N31 | 0.2935 (3) | −0.1981 (2) | 0.25025 (12) | 0.0687 (6) | |
C1 | 0.3017 (3) | −0.1229 (2) | 0.00465 (11) | 0.0460 (5) | |
H1 | 0.3292 | −0.1754 | 0.0438 | 0.055* | |
C2 | 0.2618 (3) | 0.0037 (2) | 0.01395 (10) | 0.0460 (5) | |
H2 | 0.2446 | 0.0585 | −0.0240 | 0.055* | |
C3 | 0.2459 (3) | 0.05342 (19) | 0.07643 (10) | 0.0416 (5) | |
C4 | 0.2132 (3) | 0.1838 (2) | 0.08161 (11) | 0.0462 (5) | |
H4 | 0.2117 | 0.2353 | 0.0435 | 0.055* | |
C5 | 0.1832 (3) | 0.2406 (2) | 0.13913 (10) | 0.0437 (5) | |
H5 | 0.1884 | 0.1884 | 0.1773 | 0.052* | |
C11 | 0.3487 (4) | −0.3066 (2) | −0.06035 (14) | 0.0655 (7) | |
H11A | 0.3656 | −0.3474 | −0.0158 | 0.098* | |
H11B | 0.4545 | −0.3120 | −0.0740 | 0.098* | |
H11C | 0.2559 | −0.3485 | −0.0947 | 0.098* | |
C12 | 0.2575 (4) | −0.1003 (2) | −0.11992 (11) | 0.0596 (6) | |
H12A | 0.1396 | −0.0699 | −0.1293 | 0.089* | |
H12B | 0.2672 | −0.1535 | −0.1578 | 0.089* | |
H12C | 0.3355 | −0.0291 | −0.1152 | 0.089* | |
C21 | 0.1195 (4) | 0.4114 (3) | 0.20963 (13) | 0.0647 (7) | |
H21A | 0.1345 | 0.3440 | 0.2434 | 0.097* | |
H21B | 0.0030 | 0.4449 | 0.1998 | 0.097* | |
H21C | 0.2023 | 0.4780 | 0.2280 | 0.097* | |
C22 | 0.1389 (4) | 0.4541 (2) | 0.09001 (14) | 0.0717 (8) | |
H22A | 0.2544 | 0.4694 | 0.0861 | 0.108* | |
H22B | 0.0903 | 0.5325 | 0.1008 | 0.108* | |
H22C | 0.0663 | 0.4211 | 0.0465 | 0.108* | |
C32 | 0.1698 (4) | −0.2136 (2) | 0.18975 (14) | 0.0626 (7) | |
H32 | 0.0928 | −0.2815 | 0.1858 | 0.075* | |
C33 | 0.1494 (3) | −0.1348 (2) | 0.13284 (12) | 0.0516 (5) | |
H33 | 0.0611 | −0.1502 | 0.0918 | 0.062* | |
C34 | 0.2616 (3) | −0.03225 (19) | 0.13724 (10) | 0.0406 (5) | |
C35 | 0.3878 (3) | −0.0138 (2) | 0.20049 (10) | 0.0494 (5) | |
H35 | 0.4642 | 0.0550 | 0.2065 | 0.059* | |
C36 | 0.3987 (4) | −0.0986 (3) | 0.25434 (12) | 0.0625 (7) | |
H36 | 0.4853 | −0.0853 | 0.2962 | 0.075* | |
B1 | 0.3106 (3) | 0.1668 (2) | 0.37692 (11) | 0.0590 (7) | |
F1 | 0.2062 (2) | 0.13381 (19) | 0.31236 (9) | 0.0938 (6) | |
F2 | 0.4698 (3) | 0.1104 (3) | 0.39202 (14) | 0.1248 (13) | 0.918 (5) |
F3 | 0.2298 (4) | 0.1316 (4) | 0.42561 (14) | 0.1420 (14) | 0.918 (5) |
F4 | 0.3280 (4) | 0.29452 (18) | 0.38245 (16) | 0.1267 (13) | 0.918 (5) |
F12 | 0.4433 (18) | 0.2401 (19) | 0.3687 (4) | 0.101 (7)* | 0.082 (5) |
F13 | 0.376 (3) | 0.0601 (6) | 0.4128 (5) | 0.101 (7)* | 0.082 (5) |
F14 | 0.2162 (12) | 0.233 (2) | 0.4114 (6) | 0.101 (7)* | 0.082 (5) |
U11 | U22 | U33 | U12 | U13 | U23 | |
N1 | 0.0584 (11) | 0.0492 (10) | 0.0425 (9) | 0.0009 (8) | 0.0183 (8) | −0.0048 (8) |
N2 | 0.0618 (11) | 0.0421 (10) | 0.0459 (10) | 0.0054 (8) | 0.0161 (8) | 0.0013 (8) |
N31 | 0.0935 (17) | 0.0622 (13) | 0.0594 (13) | 0.0108 (12) | 0.0361 (12) | 0.0184 (10) |
C1 | 0.0524 (12) | 0.0485 (12) | 0.0388 (10) | 0.0020 (9) | 0.0160 (9) | −0.0011 (9) |
C2 | 0.0562 (12) | 0.0465 (11) | 0.0361 (10) | 0.0018 (10) | 0.0143 (9) | 0.0041 (8) |
C3 | 0.0448 (10) | 0.0428 (11) | 0.0372 (9) | −0.0003 (9) | 0.0115 (8) | 0.0018 (8) |
C4 | 0.0584 (13) | 0.0431 (11) | 0.0380 (10) | 0.0002 (9) | 0.0153 (9) | 0.0040 (8) |
C5 | 0.0478 (11) | 0.0410 (11) | 0.0419 (10) | 0.0006 (9) | 0.0123 (9) | 0.0044 (8) |
C11 | 0.0806 (17) | 0.0556 (14) | 0.0628 (15) | 0.0082 (13) | 0.0244 (13) | −0.0095 (12) |
C12 | 0.0818 (17) | 0.0616 (15) | 0.0404 (11) | −0.0013 (13) | 0.0255 (11) | −0.0054 (10) |
C21 | 0.0826 (18) | 0.0567 (14) | 0.0601 (14) | 0.0129 (13) | 0.0288 (13) | −0.0065 (12) |
C22 | 0.105 (2) | 0.0480 (14) | 0.0655 (16) | 0.0155 (14) | 0.0294 (15) | 0.0156 (12) |
C32 | 0.0819 (17) | 0.0470 (13) | 0.0694 (16) | −0.0043 (12) | 0.0384 (14) | 0.0056 (11) |
C33 | 0.0617 (13) | 0.0453 (12) | 0.0509 (12) | −0.0026 (10) | 0.0211 (10) | −0.0002 (10) |
C34 | 0.0491 (11) | 0.0394 (10) | 0.0370 (9) | 0.0054 (8) | 0.0179 (8) | 0.0010 (8) |
C35 | 0.0531 (12) | 0.0545 (13) | 0.0416 (11) | 0.0011 (10) | 0.0152 (9) | 0.0040 (9) |
C36 | 0.0672 (15) | 0.0764 (17) | 0.0436 (12) | 0.0133 (13) | 0.0153 (11) | 0.0130 (12) |
B1 | 0.0675 (17) | 0.0479 (14) | 0.0597 (16) | −0.0004 (13) | 0.0150 (13) | −0.0053 (12) |
F1 | 0.0918 (12) | 0.1004 (14) | 0.0806 (12) | 0.0026 (10) | 0.0105 (9) | −0.0291 (10) |
F2 | 0.0929 (17) | 0.155 (3) | 0.1112 (19) | 0.0495 (17) | 0.0042 (13) | −0.0369 (17) |
F3 | 0.153 (3) | 0.182 (3) | 0.1065 (19) | −0.034 (2) | 0.0625 (18) | 0.0211 (18) |
F4 | 0.155 (3) | 0.0539 (12) | 0.151 (2) | −0.0137 (14) | 0.0111 (19) | −0.0174 (13) |
N1—C1 | 1.311 (3) | C35—C36 | 1.378 (3) |
N1—C11 | 1.450 (3) | C35—H35 | 0.93 |
N1—C12 | 1.460 (3) | C36—H36 | 0.93 |
C1—C2 | 1.390 (3) | C11—H11A | 0.96 |
C1—H1 | 0.93 | C11—H11B | 0.96 |
C2—C3 | 1.390 (3) | C11—H11C | 0.96 |
C2—H2 | 0.93 | C12—H12A | 0.96 |
C3—C4 | 1.402 (3) | C12—H12B | 0.96 |
C3—C34 | 1.486 (3) | C12—H12C | 0.96 |
C4—C5 | 1.373 (3) | C21—H21A | 0.96 |
C4—H4 | 0.93 | C21—H21B | 0.96 |
C5—H5 | 0.93 | C21—H21C | 0.96 |
N2—C5 | 1.318 (3) | C22—H22A | 0.96 |
N2—C21 | 1.457 (3) | C22—H22B | 0.96 |
N2—C22 | 1.456 (3) | C22—H22C | 0.96 |
N31—C32 | 1.333 (4) | B1—F1 | 1.364 (2) |
N31—C36 | 1.328 (4) | B1—F2 | 1.356 (2) |
C32—C33 | 1.376 (3) | B1—F3 | 1.361 (2) |
C32—H32 | 0.93 | B1—F4 | 1.348 (2) |
C33—C34 | 1.386 (3) | B1—F12 | 1.356 (3) |
C33—H33 | 0.93 | B1—F13 | 1.351 (3) |
C34—C35 | 1.385 (3) | B1—F14 | 1.350 (3) |
C1—N1—C11 | 121.7 (2) | N2—C21—H21C | 109.5 |
C1—N1—C12 | 121.63 (19) | H21A—C21—H21C | 109.5 |
C11—N1—C12 | 116.69 (19) | H21B—C21—H21C | 109.5 |
C5—N2—C22 | 122.24 (19) | N2—C22—H22A | 109.5 |
C5—N2—C21 | 121.33 (19) | N2—C22—H22B | 109.5 |
C22—N2—C21 | 116.4 (2) | H22A—C22—H22B | 109.5 |
C36—N31—C32 | 116.3 (2) | N2—C22—H22C | 109.5 |
N1—C1—C2 | 125.0 (2) | H22A—C22—H22C | 109.5 |
N1—C1—H1 | 117.5 | H22B—C22—H22C | 109.5 |
C2—C1—H1 | 117.5 | N31—C32—C33 | 123.8 (2) |
C3—C2—C1 | 124.14 (19) | N31—C32—H32 | 118.1 |
C3—C2—H2 | 117.9 | C33—C32—H32 | 118.1 |
C1—C2—H2 | 117.9 | C32—C33—C34 | 119.5 (2) |
C2—C3—C4 | 119.94 (18) | C32—C33—H33 | 120.3 |
C2—C3—C34 | 119.80 (18) | C34—C33—H33 | 120.3 |
C4—C3—C34 | 120.26 (17) | C35—C34—C33 | 117.05 (19) |
C5—C4—C3 | 124.46 (19) | C35—C34—C3 | 121.93 (19) |
C5—C4—H4 | 117.8 | C33—C34—C3 | 121.02 (18) |
C3—C4—H4 | 117.8 | C36—C35—C34 | 119.2 (2) |
N2—C5—C4 | 126.38 (19) | C36—C35—H35 | 120.4 |
N2—C5—H5 | 116.8 | C34—C35—H35 | 120.4 |
C4—C5—H5 | 116.8 | N31—C36—C35 | 124.2 (2) |
N1—C11—H11A | 109.5 | N31—C36—H36 | 117.9 |
N1—C11—H11B | 109.5 | C35—C36—H36 | 117.9 |
H11A—C11—H11B | 109.5 | F2—B1—F1 | 112.3 (2) |
N1—C11—H11C | 109.5 | F3—B1—F1 | 108.6 (2) |
H11A—C11—H11C | 109.5 | F4—B1—F1 | 110.5 (2) |
H11B—C11—H11C | 109.5 | F2—B1—F3 | 109.1 (2) |
N1—C12—H12A | 109.5 | F4—B1—F2 | 110.3 (2) |
N1—C12—H12B | 109.5 | F4—B1—F3 | 105.7 (3) |
H12A—C12—H12B | 109.5 | F12—B1—F1 | 108.5 (3) |
N1—C12—H12C | 109.5 | F13—B1—F1 | 109.2 (3) |
H12A—C12—H12C | 109.5 | F14—B1—F1 | 109.5 (3) |
H12B—C12—H12C | 109.5 | F13—B1—F12 | 109.8 (3) |
N2—C21—H21A | 109.5 | F14—B1—F12 | 109.8 (3) |
N2—C21—H21B | 109.5 | F14—B1—F13 | 110.1 (3) |
H21A—C21—H21B | 109.5 | ||
C11—N1—C1—C2 | 179.2 (2) | N31—C32—C33—C34 | −0.3 (4) |
C12—N1—C1—C2 | −1.7 (3) | C32—C33—C34—C35 | −1.2 (3) |
N1—C1—C2—C3 | 174.3 (2) | C32—C33—C34—C3 | 178.8 (2) |
C1—C2—C3—C4 | 177.1 (2) | C2—C3—C34—C35 | 120.9 (2) |
C1—C2—C3—C34 | −3.7 (3) | C4—C3—C34—C35 | −59.9 (3) |
C2—C3—C4—C5 | 175.2 (2) | C2—C3—C34—C33 | −59.1 (3) |
C3—C4—C5—N2 | −178.2 (2) | C4—C3—C34—C33 | 120.1 (2) |
C4—C5—N2—C21 | −179.5 (2) | C33—C34—C35—C36 | 1.7 (3) |
C34—C3—C4—C5 | −4.0 (3) | C3—C34—C35—C36 | −178.2 (2) |
C22—N2—C5—C4 | −1.2 (4) | C32—N31—C36—C35 | −0.7 (4) |
C36—N31—C32—C33 | 1.3 (4) | C34—C35—C36—N31 | −0.8 (4) |
Experimental details
Crystal data | |
Chemical formula | C14H20N3+·BF4− |
Mr | 317.14 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 293 |
a, b, c (Å) | 7.982 (2), 10.492 (2), 19.950 (3) |
β (°) | 106.578 (19) |
V (Å3) | 1601.3 (6) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.11 |
Crystal size (mm) | 0.38 × 0.34 × 0.20 |
Data collection | |
Diffractometer | Nonius CAD-4 diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 3931, 3482, 2306 |
Rint | 0.018 |
(sin θ/λ)max (Å−1) | 0.638 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.057, 0.195, 1.04 |
No. of reflections | 3482 |
No. of parameters | 215 |
No. of restraints | 13 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.36, −0.30 |
Computer programs: CAD-4 Software (Enraf-Nonius, 1992), SET4 and CELDIM (Enraf-Nonius, 1992), HELENA in PLATON (Spek, 2001), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), ORTEPII (Johnson, 1976) and PLATON (Spek, 2001), SHELXL97.
N1—C1 | 1.311 (3) | C4—C5 | 1.373 (3) |
N1—C11 | 1.450 (3) | N2—C5 | 1.318 (3) |
N1—C12 | 1.460 (3) | N2—C21 | 1.457 (3) |
C1—C2 | 1.390 (3) | N2—C22 | 1.456 (3) |
C2—C3 | 1.390 (3) | N31—C32 | 1.333 (4) |
C3—C4 | 1.402 (3) | N31—C36 | 1.328 (4) |
C3—C34 | 1.486 (3) | ||
C11—N1—C1—C2 | 179.2 (2) | C2—C3—C4—C5 | 175.2 (2) |
N1—C1—C2—C3 | 174.3 (2) | C3—C4—C5—N2 | −178.2 (2) |
C1—C2—C3—C4 | 177.1 (2) | C4—C5—N2—C21 | −179.5 (2) |
The title salt, (I), containing the relatively electron-poor 4-pyridyl substituent, was prepared in order to determine what effect (if any) the 4-pyridyl substitution at C3 would have on the conformation of the pentamethinecyanine moiety of the cation. The perchlorate salt analogue of (I) has been prepared (Hanke & Jutz, 1980), but a search of the Cambridge Structural Database (Allen & Kennard, 1993) showed that its structure had not been reported.
The crystal structure of (I) consists of discrete cations and tetrafluroborate anions, the latter being disordered over two sites. The pentamethinecyanine moiety of the cation (N1/C1—C5/N2) is essentially planar and adopts an all-trans conformation which makes a dihedral angle of 60.58 (9)° with the pyridine plane (Fig. 1). The planar terminal dimethylamino groups are rotated in opposite directions through 5.83 (12) and 6.69 (17)° out of the pentamethinecyanine plane. Bond lengths within the pentamethinecyanine fragment [C—C = 1.373 (3)–1.402 (3) Å; C—N = 1.311 (3) and 1.318 (3) Å] are similar to those reported in charge-density studies (Honda et al., 1986) for the parent perchlorate salt (II), indicating minimal perturbation of the pentamethinecyanine moiety by the (4-pyridyl) substituent at C3. Bond lengths within the pyridine fragment are normal; the C3—C34 bond length [1.486 (3) Å] linking the cyanine and pyridine moieties is entirely consistent with its being a Csp2—Csp2 single bond. The cation dimensions and conformation are thus indicative of a lack of direct conjugative interaction between the two π systems. A coplanar arrangement of these two moieties would not be possible with the pentamethinecyanine fragment in the all-trans conformation because of severe steric interactions which would be present between the pyridine β-H atoms and the C1 and C5 H atoms of the cyanine moiety in the planar conformation. This situation is similar to that reported (Katoh et al., 1997) for the bis(pentamethinecyanine) salt (III) in which two electron-poor pentamethinecyanine units each have an all-trans conformation and are linked through their central C atoms; the cation has a conformation in which the two pentamethinecyanine moieties are mutually at right angles.
The 1H NMR chemical shifts found for (I) in DMSO-d6 are similar to those reported (Hanke & Jutz, 1980) for the perchlorate analogue. However, in the present case, two closely-spaced NMe signals were observed instead of one and coupling of the pyridine protons signals was resolved. In the case of the perchlorate salt, the latter signals were reported as broad multiplets. It is possible that the broadening was due to ion-pairing effects. Thus, when the spectrum of (I) was run in CDCl3 [dilute solution due to low solubility of (I) in this solvent], two sets of pyridine signals were observed, while the remaining signals were unchanged. In the less polar solvent, tight ion pairing between the cations and tetrafluoroborate anions would be expected to occur. If the anion lies over one face of the pentamethinecyanine moiety, and migration of the anion between faces is slow on the NMR time scale, this would lead to discrimination between the two faces, and different environments for the α and β proton pairs of the pyridine moiety only.