Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536803017252/bt6322sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536803017252/bt6322Isup2.hkl |
CCDC reference: 222789
The synthetic strategy for the preparation of pyridylalanines and the reaction leading to the formation of the title compound are described by Tabanella et al. (2003). A zinc reagent derived from iodoalanine was treated with 2-amino-6-bromopyridine and with dichlorobis(triphenylphosphine)palladium as a coupling catalyst, and the title compound was isolated by recrystallization of the crude reaction mixture from ethyl acetate.
H atoms were placed geometrically and refined with a riding model (including free rotation about C—C bonds), and with Uiso constrained to be 1.2 (1.5 for methyl groups) times Ueq of the carrier atom; N—H distances were set at 0.88 Å, and C—H to 0.95 (aromatic), 0.98 (methyl) or 0.99 Å (methylene). Both methyl groups of the solvent molecule were found to be disordered, each with two sets of H atoms, which were constrained to ideal tetrahedral angles and assigned equal occupancy factors. The largest peaks in the final difference synthesis lie close to the Pd and I atoms.
Data collection: SMART (Bruker, 2001); cell refinement: local programs; data reduction: SAINT (Bruker, 2001); program(s) used to solve structure: SHELXTL (Sheldrick, 2001); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and local programs.
[Pd(C5H6N2)(C18H15P}2]I·C4H8O2 | Dx = 1.608 Mg m−3 |
Mr = 1066.96 | Mo Kα radiation, λ = 0.71073 Å |
Orthorhombic, Cmc21 | Cell parameters from 13025 reflections |
a = 15.0297 (9) Å | θ = 2.2–28.8° |
b = 16.9603 (10) Å | µ = 1.93 mm−1 |
c = 17.2897 (11) Å | T = 160 K |
V = 4407.3 (5) Å3 | Plate, pale yellow |
Z = 4 | 0.40 × 0.21 × 0.10 mm |
F(000) = 2104 |
Bruker SMART 1K CCD diffractometer | 5016 independent reflections |
Radiation source: sealed tube | 4828 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.030 |
Detector resolution: 8.192 pixels mm-1 | θmax = 28.8°, θmin = 1.8° |
narrow–frame ω scans | h = −19→19 |
Absorption correction: multi-scan (SADABS; Sheldrick, 2002) | k = −22→17 |
Tmin = 0.600, Tmax = 0.824 | l = −23→19 |
14181 measured reflections |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.026 | H-atom parameters constrained |
wR(F2) = 0.066 | w = 1/[σ2(Fo2) + (0.0393P)2 + 0.905P] where P = (Fo2 + 2Fc2)/3 |
S = 1.04 | (Δ/σ)max = 0.001 |
5016 reflections | Δρmax = 1.28 e Å−3 |
270 parameters | Δρmin = −0.71 e Å−3 |
1 restraint | Absolute structure: Flack (1983); 2220 Friedel pairs |
Primary atom site location: structure-invariant direct methods | Absolute structure parameter: −0.005 (16) |
[Pd(C5H6N2)(C18H15P}2]I·C4H8O2 | V = 4407.3 (5) Å3 |
Mr = 1066.96 | Z = 4 |
Orthorhombic, Cmc21 | Mo Kα radiation |
a = 15.0297 (9) Å | µ = 1.93 mm−1 |
b = 16.9603 (10) Å | T = 160 K |
c = 17.2897 (11) Å | 0.40 × 0.21 × 0.10 mm |
Bruker SMART 1K CCD diffractometer | 5016 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 2002) | 4828 reflections with I > 2σ(I) |
Tmin = 0.600, Tmax = 0.824 | Rint = 0.030 |
14181 measured reflections |
R[F2 > 2σ(F2)] = 0.026 | H-atom parameters constrained |
wR(F2) = 0.066 | Δρmax = 1.28 e Å−3 |
S = 1.04 | Δρmin = −0.71 e Å−3 |
5016 reflections | Absolute structure: Flack (1983); 2220 Friedel pairs |
270 parameters | Absolute structure parameter: −0.005 (16) |
1 restraint |
x | y | z | Uiso*/Ueq | Occ. (<1) | |
Pd1 | 0.5000 | 0.278578 (18) | 0.282560 (19) | 0.01377 (7) | |
I1 | 0.5000 | 0.420395 (18) | 0.21713 (2) | 0.02785 (9) | |
C1 | 0.5000 | 0.1796 (3) | 0.3462 (3) | 0.0177 (9) | |
N1 | 0.5000 | 0.1095 (2) | 0.3084 (2) | 0.0209 (8) | |
H1 | 0.5000 | 0.1114 | 0.2576 | 0.025* | |
C2 | 0.5000 | 0.0360 (3) | 0.3416 (3) | 0.0279 (11) | |
N2 | 0.5000 | −0.0265 (3) | 0.2959 (3) | 0.0354 (11) | |
H2A | 0.5000 | −0.0204 | 0.2454 | 0.042* | |
H2B | 0.5000 | −0.0741 | 0.3161 | 0.042* | |
C3 | 0.5000 | 0.0335 (3) | 0.4235 (3) | 0.0304 (12) | |
H3 | 0.5000 | −0.0158 | 0.4496 | 0.036* | |
C4 | 0.5000 | 0.1024 (3) | 0.4646 (3) | 0.0310 (13) | |
H4 | 0.5000 | 0.1006 | 0.5195 | 0.037* | |
C5 | 0.5000 | 0.1769 (3) | 0.4264 (3) | 0.0240 (10) | |
H5 | 0.5000 | 0.2243 | 0.4556 | 0.029* | |
P1 | 0.65508 (4) | 0.27780 (4) | 0.28541 (5) | 0.01498 (14) | |
C6 | 0.7082 (2) | 0.32603 (18) | 0.20310 (19) | 0.0169 (6) | |
C7 | 0.7793 (2) | 0.3781 (2) | 0.2112 (2) | 0.0250 (7) | |
H7 | 0.8013 | 0.3910 | 0.2611 | 0.030* | |
C8 | 0.8176 (3) | 0.4111 (2) | 0.1457 (3) | 0.0318 (9) | |
H8 | 0.8648 | 0.4479 | 0.1511 | 0.038* | |
C9 | 0.7880 (3) | 0.3910 (2) | 0.0725 (2) | 0.0282 (8) | |
H9 | 0.8154 | 0.4134 | 0.0281 | 0.034* | |
C10 | 0.7193 (3) | 0.3389 (2) | 0.0645 (2) | 0.0286 (8) | |
H10 | 0.6997 | 0.3245 | 0.0142 | 0.034* | |
C11 | 0.6778 (2) | 0.3068 (2) | 0.1291 (2) | 0.0242 (7) | |
H11 | 0.6289 | 0.2718 | 0.1229 | 0.029* | |
C12 | 0.6957 (2) | 0.32586 (19) | 0.3731 (2) | 0.0189 (7) | |
C13 | 0.6376 (2) | 0.3692 (2) | 0.4194 (2) | 0.0252 (7) | |
H13 | 0.5772 | 0.3752 | 0.4042 | 0.030* | |
C14 | 0.6676 (3) | 0.4039 (2) | 0.4878 (2) | 0.0307 (8) | |
H14 | 0.6274 | 0.4322 | 0.5200 | 0.037* | |
C15 | 0.7567 (3) | 0.3967 (2) | 0.5087 (2) | 0.0341 (9) | |
H15 | 0.7776 | 0.4210 | 0.5548 | 0.041* | |
C16 | 0.8155 (3) | 0.3540 (2) | 0.4626 (2) | 0.0314 (8) | |
H16 | 0.8761 | 0.3490 | 0.4773 | 0.038* | |
C17 | 0.7853 (2) | 0.3189 (2) | 0.3949 (2) | 0.0261 (7) | |
H17 | 0.8254 | 0.2899 | 0.3634 | 0.031* | |
C18 | 0.71207 (19) | 0.18245 (18) | 0.2894 (2) | 0.0176 (6) | |
C19 | 0.7548 (2) | 0.1507 (2) | 0.2255 (2) | 0.0293 (8) | |
H19 | 0.7531 | 0.1778 | 0.1775 | 0.035* | |
C20 | 0.8002 (3) | 0.0797 (2) | 0.2313 (3) | 0.0377 (10) | |
H20 | 0.8304 | 0.0589 | 0.1875 | 0.045* | |
C21 | 0.8013 (3) | 0.0394 (2) | 0.3002 (2) | 0.0334 (9) | |
H21 | 0.8328 | −0.0090 | 0.3041 | 0.040* | |
C22 | 0.7570 (3) | 0.0690 (2) | 0.3638 (2) | 0.0297 (8) | |
H22 | 0.7571 | 0.0405 | 0.4111 | 0.036* | |
C23 | 0.7125 (2) | 0.1402 (2) | 0.3585 (2) | 0.0236 (7) | |
H23 | 0.6819 | 0.1605 | 0.4023 | 0.028* | |
I2 | 0.5000 | 0.09769 (2) | 0.11255 (2) | 0.03015 (9) | |
C24 | 0.5000 | −0.2651 (8) | 0.2157 (9) | 0.120 (6) | |
H24A | 0.4633 | −0.2223 | 0.1947 | 0.180* | 0.50 |
H24B | 0.4756 | −0.3159 | 0.1991 | 0.180* | 0.50 |
H24C | 0.5611 | −0.2597 | 0.1965 | 0.180* | 0.50 |
C25 | 0.5000 | −0.2605 (5) | 0.3083 (8) | 0.080 (4) | |
O1 | 0.5000 | −0.1948 (3) | 0.3390 (4) | 0.0605 (15) | |
O2 | 0.5000 | −0.3250 (4) | 0.3347 (7) | 0.111 (3) | |
C26 | 0.5000 | −0.3210 (6) | 0.4186 (7) | 0.069 (3) | |
H26A | 0.4466 | −0.2924 | 0.4369 | 0.083* | 0.50 |
H26B | 0.5534 | −0.2924 | 0.4369 | 0.083* | 0.50 |
C27 | 0.5000 | −0.4071 (6) | 0.4510 (10) | 0.101 (4) | |
H27A | 0.4812 | −0.4065 | 0.5052 | 0.152* | 0.50 |
H27B | 0.5601 | −0.4292 | 0.4471 | 0.152* | 0.50 |
H27C | 0.4587 | −0.4395 | 0.4208 | 0.152* | 0.50 |
U11 | U22 | U33 | U12 | U13 | U23 | |
Pd1 | 0.01199 (13) | 0.01359 (15) | 0.01575 (16) | 0.000 | 0.000 | 0.00026 (12) |
I1 | 0.02021 (15) | 0.01820 (14) | 0.0452 (2) | 0.000 | 0.000 | 0.00699 (14) |
C1 | 0.0101 (18) | 0.021 (2) | 0.022 (2) | 0.000 | 0.000 | 0.0016 (17) |
N1 | 0.025 (2) | 0.021 (2) | 0.016 (2) | 0.000 | 0.000 | 0.0053 (15) |
C2 | 0.028 (3) | 0.019 (2) | 0.037 (3) | 0.000 | 0.000 | 0.010 (2) |
N2 | 0.058 (3) | 0.021 (2) | 0.027 (3) | 0.000 | 0.000 | 0.0026 (19) |
C3 | 0.025 (3) | 0.031 (3) | 0.036 (3) | 0.000 | 0.000 | 0.016 (2) |
C4 | 0.027 (3) | 0.044 (3) | 0.022 (3) | 0.000 | 0.000 | 0.017 (2) |
C5 | 0.025 (2) | 0.032 (3) | 0.015 (2) | 0.000 | 0.000 | 0.0048 (19) |
P1 | 0.0124 (3) | 0.0171 (3) | 0.0154 (4) | 0.0000 (3) | −0.0001 (3) | 0.0003 (3) |
C6 | 0.0161 (14) | 0.0191 (15) | 0.0155 (17) | 0.0015 (11) | 0.0018 (11) | 0.0002 (12) |
C7 | 0.0232 (15) | 0.0276 (16) | 0.0243 (17) | −0.0055 (13) | −0.0003 (14) | 0.0021 (15) |
C8 | 0.0251 (18) | 0.039 (2) | 0.031 (2) | −0.0112 (15) | 0.0031 (15) | 0.0067 (16) |
C9 | 0.0280 (19) | 0.032 (2) | 0.025 (2) | 0.0011 (15) | 0.0055 (15) | 0.0072 (15) |
C10 | 0.037 (2) | 0.034 (2) | 0.0151 (17) | −0.0003 (16) | 0.0014 (15) | 0.0004 (14) |
C11 | 0.0229 (17) | 0.0267 (18) | 0.023 (2) | −0.0034 (13) | −0.0003 (13) | 0.0020 (13) |
C12 | 0.0203 (15) | 0.0173 (15) | 0.0191 (17) | −0.0049 (12) | −0.0015 (12) | 0.0018 (12) |
C13 | 0.0239 (17) | 0.0264 (17) | 0.0254 (19) | −0.0030 (14) | 0.0005 (13) | −0.0024 (14) |
C14 | 0.041 (2) | 0.0295 (19) | 0.022 (2) | −0.0033 (16) | 0.0049 (16) | −0.0057 (14) |
C15 | 0.053 (3) | 0.032 (2) | 0.0179 (19) | −0.0134 (17) | −0.0102 (17) | 0.0021 (14) |
C16 | 0.034 (2) | 0.0325 (19) | 0.028 (2) | −0.0069 (15) | −0.0129 (16) | 0.0045 (16) |
C17 | 0.0224 (16) | 0.0245 (18) | 0.031 (2) | −0.0009 (13) | −0.0051 (15) | 0.0015 (14) |
C18 | 0.0141 (13) | 0.0160 (14) | 0.0228 (17) | 0.0012 (11) | 0.0004 (13) | −0.0006 (13) |
C19 | 0.042 (2) | 0.0287 (18) | 0.0176 (18) | 0.0089 (15) | −0.0002 (14) | −0.0009 (16) |
C20 | 0.057 (3) | 0.0292 (19) | 0.027 (2) | 0.0159 (17) | 0.0068 (19) | −0.0036 (15) |
C21 | 0.041 (2) | 0.0219 (18) | 0.037 (3) | 0.0111 (15) | −0.0027 (16) | 0.0018 (15) |
C22 | 0.036 (2) | 0.0235 (19) | 0.029 (2) | 0.0057 (15) | 0.0010 (16) | 0.0078 (15) |
C23 | 0.0207 (15) | 0.0268 (17) | 0.0232 (17) | 0.0054 (13) | 0.0029 (13) | 0.0051 (14) |
I2 | 0.02745 (17) | 0.0432 (2) | 0.01984 (17) | 0.000 | 0.000 | 0.00002 (15) |
C24 | 0.057 (6) | 0.130 (10) | 0.173 (15) | 0.000 | 0.000 | −0.078 (11) |
C25 | 0.022 (3) | 0.046 (5) | 0.172 (12) | 0.000 | 0.000 | 0.025 (6) |
O1 | 0.040 (3) | 0.035 (3) | 0.106 (5) | 0.000 | 0.000 | 0.021 (3) |
O2 | 0.051 (4) | 0.059 (4) | 0.224 (12) | 0.000 | 0.000 | −0.005 (5) |
C26 | 0.055 (5) | 0.069 (6) | 0.084 (7) | 0.000 | 0.000 | 0.034 (5) |
C27 | 0.087 (8) | 0.073 (7) | 0.143 (12) | 0.000 | 0.000 | 0.035 (7) |
Pd1—I1 | 2.6580 (5) | C13—H13 | 0.950 |
Pd1—C1 | 2.006 (4) | C13—C14 | 1.397 (5) |
Pd1—P1 | 2.3313 (7) | C14—H14 | 0.950 |
Pd1—P1i | 2.3313 (7) | C14—C15 | 1.394 (6) |
C1—N1 | 1.356 (6) | C15—H15 | 0.950 |
C1—C5 | 1.388 (7) | C15—C16 | 1.393 (6) |
N1—H1 | 0.880 | C16—H16 | 0.950 |
N1—C2 | 1.372 (6) | C16—C17 | 1.389 (5) |
C2—N2 | 1.322 (7) | C17—H17 | 0.950 |
C2—C3 | 1.416 (8) | C18—C19 | 1.385 (5) |
N2—H2A | 0.880 | C18—C23 | 1.394 (5) |
N2—H2B | 0.880 | C19—H19 | 0.950 |
C3—H3 | 0.950 | C19—C20 | 1.388 (5) |
C3—C4 | 1.369 (9) | C20—H20 | 0.950 |
C4—H4 | 0.950 | C20—C21 | 1.373 (6) |
C4—C5 | 1.425 (7) | C21—H21 | 0.950 |
C5—H5 | 0.950 | C21—C22 | 1.381 (5) |
P1—C6 | 1.825 (3) | C22—H22 | 0.950 |
P1—C12 | 1.826 (3) | C22—C23 | 1.384 (5) |
P1—C18 | 1.831 (3) | C23—H23 | 0.950 |
C6—C7 | 1.393 (4) | C24—H24A | 0.980 |
C6—C11 | 1.398 (5) | C24—H24B | 0.980 |
C7—H7 | 0.950 | C24—H24C | 0.980 |
C7—C8 | 1.389 (5) | C24—C25 | 1.603 (18) |
C8—H8 | 0.950 | C25—O1 | 1.236 (12) |
C8—C9 | 1.382 (6) | C25—O2 | 1.185 (12) |
C9—H9 | 0.950 | O2—C26 | 1.453 (14) |
C9—C10 | 1.367 (5) | C26—H26A | 0.990 |
C10—H10 | 0.950 | C26—H26B | 0.990 |
C10—C11 | 1.391 (5) | C26—C27 | 1.564 (13) |
C11—H11 | 0.950 | C27—H27A | 0.980 |
C12—C13 | 1.395 (5) | C27—H27B | 0.980 |
C12—C17 | 1.403 (5) | C27—H27C | 0.980 |
I1—Pd1—C1 | 171.95 (14) | C12—C13—C14 | 120.4 (3) |
I1—Pd1—P1 | 90.81 (2) | H13—C13—C14 | 119.8 |
I1—Pd1—P1i | 90.81 (2) | C13—C14—H14 | 120.2 |
C1—Pd1—P1 | 89.06 (2) | C13—C14—C15 | 119.5 (4) |
C1—Pd1—P1i | 89.06 (2) | H14—C14—C15 | 120.2 |
P1—Pd1—P1i | 177.49 (5) | C14—C15—H15 | 119.8 |
Pd1—C1—N1 | 118.0 (3) | C14—C15—C16 | 120.5 (4) |
Pd1—C1—C5 | 125.2 (4) | H15—C15—C16 | 119.8 |
N1—C1—C5 | 116.8 (4) | C15—C16—H16 | 120.1 |
C1—N1—H1 | 116.7 | C15—C16—C17 | 119.9 (4) |
C1—N1—C2 | 126.6 (4) | H16—C16—C17 | 120.1 |
H1—N1—C2 | 116.7 | C12—C17—C16 | 120.3 (3) |
N1—C2—N2 | 118.6 (5) | C12—C17—H17 | 119.9 |
N1—C2—C3 | 116.5 (5) | C16—C17—H17 | 119.9 |
N2—C2—C3 | 124.9 (5) | P1—C18—C19 | 122.0 (3) |
C2—N2—H2A | 120.0 | P1—C18—C23 | 119.2 (3) |
C2—N2—H2B | 120.0 | C19—C18—C23 | 118.8 (3) |
H2A—N2—H2B | 120.0 | C18—C19—H19 | 119.7 |
C2—C3—H3 | 120.2 | C18—C19—C20 | 120.5 (4) |
C2—C3—C4 | 119.5 (5) | H19—C19—C20 | 119.7 |
H3—C3—C4 | 120.2 | C19—C20—H20 | 120.0 |
C3—C4—H4 | 119.5 | C19—C20—C21 | 120.0 (4) |
C3—C4—C5 | 121.1 (5) | H20—C20—C21 | 120.0 |
H4—C4—C5 | 119.5 | C20—C21—H21 | 119.9 |
C1—C5—C4 | 119.6 (5) | C20—C21—C22 | 120.3 (3) |
C1—C5—H5 | 120.2 | H21—C21—C22 | 119.9 |
C4—C5—H5 | 120.2 | C21—C22—H22 | 120.1 |
Pd1—P1—C6 | 114.73 (10) | C21—C22—C23 | 119.9 (3) |
Pd1—P1—C12 | 110.45 (11) | H22—C22—C23 | 120.1 |
Pd1—P1—C18 | 118.26 (10) | C18—C23—C22 | 120.5 (3) |
C6—P1—C12 | 107.51 (14) | C18—C23—H23 | 119.8 |
C6—P1—C18 | 102.71 (15) | C22—C23—H23 | 119.8 |
C12—P1—C18 | 101.94 (16) | H24A—C24—H24B | 109.5 |
P1—C6—C7 | 122.8 (3) | H24A—C24—H24C | 109.5 |
P1—C6—C11 | 117.8 (2) | H24A—C24—C25 | 109.5 |
C7—C6—C11 | 119.4 (3) | H24B—C24—H24C | 109.5 |
C6—C7—H7 | 120.3 | H24B—C24—C25 | 109.5 |
C6—C7—C8 | 119.4 (3) | H24C—C24—C25 | 109.5 |
H7—C7—C8 | 120.3 | C24—C25—O1 | 118.3 (9) |
C7—C8—H8 | 119.5 | C24—C25—O2 | 109.9 (12) |
C7—C8—C9 | 120.9 (3) | O1—C25—O2 | 131.8 (14) |
H8—C8—C9 | 119.5 | C25—O2—C26 | 110.0 (10) |
C8—C9—H9 | 120.2 | O2—C26—H26A | 110.0 |
C8—C9—C10 | 119.7 (3) | O2—C26—H26B | 110.0 |
H9—C9—C10 | 120.2 | O2—C26—C27 | 108.3 (10) |
C9—C10—H10 | 119.6 | H26A—C26—H26B | 108.4 |
C9—C10—C11 | 120.7 (4) | H26A—C26—C27 | 110.0 |
H10—C10—C11 | 119.6 | H26B—C26—C27 | 110.0 |
C6—C11—C10 | 119.8 (3) | C26—C27—H27A | 109.5 |
C6—C11—H11 | 120.1 | C26—C27—H27B | 109.5 |
C10—C11—H11 | 120.1 | C26—C27—H27C | 109.5 |
P1—C12—C13 | 120.1 (2) | H27A—C27—H27B | 109.5 |
P1—C12—C17 | 120.4 (3) | H27A—C27—H27C | 109.5 |
C13—C12—C17 | 119.4 (3) | H27B—C27—H27C | 109.5 |
C12—C13—H13 | 119.8 |
Symmetry code: (i) −x+1, y, z. |
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1···I2 | 0.88 | 2.52 | 3.393 (4) | 173 |
N2—H2A···I2 | 0.88 | 3.05 | 3.806 (5) | 146 |
N2—H2B···O1 | 0.88 | 2.08 | 2.950 (6) | 168 |
Experimental details
Crystal data | |
Chemical formula | [Pd(C5H6N2)(C18H15P}2]I·C4H8O2 |
Mr | 1066.96 |
Crystal system, space group | Orthorhombic, Cmc21 |
Temperature (K) | 160 |
a, b, c (Å) | 15.0297 (9), 16.9603 (10), 17.2897 (11) |
V (Å3) | 4407.3 (5) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 1.93 |
Crystal size (mm) | 0.40 × 0.21 × 0.10 |
Data collection | |
Diffractometer | Bruker SMART 1K CCD diffractometer |
Absorption correction | Multi-scan (SADABS; Sheldrick, 2002) |
Tmin, Tmax | 0.600, 0.824 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 14181, 5016, 4828 |
Rint | 0.030 |
(sin θ/λ)max (Å−1) | 0.678 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.026, 0.066, 1.04 |
No. of reflections | 5016 |
No. of parameters | 270 |
No. of restraints | 1 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 1.28, −0.71 |
Absolute structure | Flack (1983); 2220 Friedel pairs |
Absolute structure parameter | −0.005 (16) |
Computer programs: SMART (Bruker, 2001), SAINT (Bruker, 2001), SHELXTL (Sheldrick, 2001), SHELXTL and local programs.
Pd1—I1 | 2.6580 (5) | Pd1—P1 | 2.3313 (7) |
Pd1—C1 | 2.006 (4) | ||
I1—Pd1—C1 | 171.95 (14) | C1—Pd1—P1 | 89.06 (2) |
I1—Pd1—P1 | 90.81 (2) | P1—Pd1—P1i | 177.49 (5) |
Symmetry code: (i) −x+1, y, z. |
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1···I2 | 0.88 | 2.52 | 3.393 (4) | 173 |
N2—H2A···I2 | 0.88 | 3.05 | 3.806 (5) | 146 |
N2—H2B···O1 | 0.88 | 2.08 | 2.950 (6) | 168 |
The title compound, (I), was obtained unexpectedly as a by-product in a reaction exploring the synthesis of enantiomerically pure pyridylamino acids via palladium-catalysed cross-coupling of serine-derived organozinc reagents with various halopyridines (Tabanella et al., 2003). It is presumably derived from the product of oxidative addition of 2-amino-6-bromopyridine to bis(triphenylphosphine)palladium(0), followed by exchange of bromide for iodide, originating from the zinc reagent. Similar products have been obtained by other researchers in related reactions (Spee et al., 2000; Bocelli et al., 1998).
The complex cation (Fig. 1) contains Pd in a square-planar coordination environment, bonded to two trans-triphenylphosphine ligands, one iodide, and an amino-substituted pyridyl group through its ortho-C atom. This pyridyl ligand is protonated on the ring N atom, and it forms two hydrogen bonds to the uncoordinated second iodide anion, one from the pyridinium N—H and the other from the 6-amino NH2 group. The second H atom of the amino group is hydrogen bonded to the ethyl acetate solvent molecule (Fig. 2), which has relatively large anisotropic displacement parameters and may be subject to unresolved disorder in addition to the disorder detected and modelled for its two methyl groups. The Pd atom, both iodides, all atoms of the pyridyl ligand, and all non-H atoms of the solvent molecule lie in a crystallographic mirror plane, which relates the two phosphine ligands to each other. Deviations from ideal square-planar coordination geometry are small, as can be seen in Table 1 and in the figures. Apart from the hydrogen bonding, there are no significant intermolecular interactions.
Pyridyl complexes of palladium with a Pd—C bond are not unknown, but there are few reported crystal structures. A search of the Cambridge Structural Database (CSD, Version 5.24 with two updates, April 2003; Allen, 2002) finds seven. In every case, the other ligands are a combination of phosphines and halides. Except for one complex with a chelating diphosphine, which imposes a cis configuration (Chin et al., 1998), the pyridyl ligand always lies trans to a halide (Cave et al., 1999; Isobe et al., 1980; Newkome et al., 1987; Benetollo et al., 1991), as is the case here.
The CSD contains 100 structures of bis(phosphine) complexes of palladium with a Pd—C bond trans to a halide ligand. 12 of these have iodine as the halogen, nine of them with a substituted or unsubstituted phenyl or pyridyl ligand. For these, the Pd—C distances range from 2.009 to 2.048 Å, and the Pd—I distances from 2.680 to 2.706 Å. The title complex thus has both the shortest Pd—I bond and (marginally) the shortest Pd—C bond. The values are in accordance with the known relative trans influences of aryl and iodo ligands (e.g. Spee et al., 2000; Vicente et al., 1999; Flemming et al., 1998).