metal-organic compounds
Pentacarbonyl{3-[(2S)-1-methylpyrrolidin-2-yl]pyridine}tungsten(0)
aUniversity of the Western Cape, Cape Town, Bellville 7535, South Africa, bDepartment of Chemistry, Rutgers, the State University of New Jersey, 73 Warren St, Newark, NJ 07102, USA, and cDepartment of Chemistry, Kenyatta University, PO Box 43844-00100, Nairobi, Kenya
*Correspondence e-mail: monani@uwc.ac.za
The title compound, [W(C10H14N2)(CO)5], contains five carbonyl ligands and a nicotine ligand in an octahedral arrangement around the tungsten atom. The metal atom shows cis angles in the range 87.30 (16)–94.2 (2)°, and trans angles between 175.2 (2) and 178.1 (4)°. The W—CO bond trans to the pyridine N atom [1.987 (6) Å] is noticeably shorter than the others, which range between 2.036 (3) and 2.064 (3) Å, possibly due to the well-known trans effect. The distance between the W atom and the pyridine N atom is 2.278 (4) Å.
Related literature
Attempts to understand and mimic the nature of nitrogen fixation have led to studies on the responsible enzyme, nitrogenase (Jennings, 1991; Schrock, 2006). As part of this work, we have investigated the reactions of the precursor tungsten halogenidocarbonyl derivative, [W(CO)4X2]2, with nitrogen bases. For possible reaction mechanisms, see: Abel et al. (1963); Baker (1998); Heyns & Buchholtz (1976); Tripathi & Srivasatva (1970). For the preparation of tungsten dichloridotetracarbonyl [W(CO)4Cl2], see: Colton & Tomkins (1966).
Experimental
Crystal data
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Data collection: APEX2 (Bruker, 2006); cell SAINT (Bruker, 2005); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008b); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.
Supporting information
10.1107/S1600536810010974/ez2203sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536810010974/ez2203Isup2.hkl
The procedure by Colton and Tomkins (1966) and Schlenk techniques were used to prepare tungsten halocarbonyl [W(CO)4Cl2]. This halocarbonyl (13.13 mmol) was then reacted in situ with the base, nicotine (31.13 mmol), dissolved in freshly distilled methanol (20 ml) at -78 °C and the mixture left to warm to room temperature while stirring. The solution was stirred at room temperature for 14 h after which the solvent was removed under vacuum and the residue washed with portions of dry freshly distilled methanol and rinsed with diethylether. A yellow product was obtained in medium yield.
The crystal was grown at 4°C using a slow diffusion of dichloromethane over hexane for several days.
All H atoms for (I) were found in electron density difference maps. The methyl H atoms were put in ideally staggered positions with C—H distances of 0.98 Å and Uiso(H) = 1.5Ueq(C). The methylene, methine and phenyl Hs were placed in geometrically idealized positions and constrained to ride on their parent C atoms with C—H distances of 0.99, 1.00 and 0.95 Å, respectively, and Uiso(H) = 1.2Ueq(C).
Data collection: APEX2 (Bruker, 2006); cell
SAINT (Bruker, 2005); data reduction: SAINT (Bruker, 2005); program(s) used to solve structure: SHELXTL (Sheldrick, 2008b); program(s) used to refine structure: SHELXTL (Sheldrick, 2008b); molecular graphics: SHELXTL (Sheldrick, 2008b); software used to prepare material for publication: SHELXTL (Sheldrick, 2008b).Fig. 1. : The structure of the asymmetric unit of (I) with its numbering scheme. Displacement ellipsoids are drawn at the 40% probability level for non-H atoms. |
[W(C10H14N2)(CO)5] | F(000) = 464 |
Mr = 486.13 | Dx = 1.968 Mg m−3 |
Monoclinic, P21 | Cu Kα radiation, λ = 1.54178 Å |
Hall symbol: P 2yb | Cell parameters from 6772 reflections |
a = 6.6303 (1) Å | θ = 3.8–66.8° |
b = 10.6720 (2) Å | µ = 13.29 mm−1 |
c = 11.6748 (2) Å | T = 100 K |
β = 96.636 (1)° | Plate, yellow |
V = 820.56 (2) Å3 | 0.28 × 0.25 × 0.19 mm |
Z = 2 |
Bruker SMART CCD APEXII area-detector diffractometer | 2676 independent reflections |
Radiation source: fine-focus sealed tube | 2673 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.020 |
ϕ and ω scans | θmax = 66.8°, θmin = 3.8° |
Absorption correction: numerical (SADABS; Sheldrick, 2008a) | h = −7→7 |
Tmin = 0.119, Tmax = 0.185 | k = −12→12 |
6704 measured reflections | l = −13→11 |
Refinement on F2 | Hydrogen site location: inferred from neighbouring sites |
Least-squares matrix: full | H-atom parameters constrained |
R[F2 > 2σ(F2)] = 0.014 | w = 1/[σ2(Fo2) + (0.0071P)2] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.033 | (Δ/σ)max < 0.001 |
S = 1.13 | Δρmax = 0.44 e Å−3 |
2676 reflections | Δρmin = −0.53 e Å−3 |
210 parameters | Extinction correction: SHELXTL (Sheldrick, 2008b), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
1 restraint | Extinction coefficient: 0.00053 (7) |
Primary atom site location: structure-invariant direct methods | Absolute structure: Flack (1983), 1225 Friedel pairs |
Secondary atom site location: difference Fourier map | Absolute structure parameter: 0.041 (9) |
[W(C10H14N2)(CO)5] | V = 820.56 (2) Å3 |
Mr = 486.13 | Z = 2 |
Monoclinic, P21 | Cu Kα radiation |
a = 6.6303 (1) Å | µ = 13.29 mm−1 |
b = 10.6720 (2) Å | T = 100 K |
c = 11.6748 (2) Å | 0.28 × 0.25 × 0.19 mm |
β = 96.636 (1)° |
Bruker SMART CCD APEXII area-detector diffractometer | 2676 independent reflections |
Absorption correction: numerical (SADABS; Sheldrick, 2008a) | 2673 reflections with I > 2σ(I) |
Tmin = 0.119, Tmax = 0.185 | Rint = 0.020 |
6704 measured reflections |
R[F2 > 2σ(F2)] = 0.014 | H-atom parameters constrained |
wR(F2) = 0.033 | Δρmax = 0.44 e Å−3 |
S = 1.13 | Δρmin = −0.53 e Å−3 |
2676 reflections | Absolute structure: Flack (1983), 1225 Friedel pairs |
210 parameters | Absolute structure parameter: 0.041 (9) |
1 restraint |
Experimental. 'crystal mounted on a Cryoloop using Paratone-N' |
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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. |
x | y | z | Uiso*/Ueq | ||
W1 | 0.975072 (14) | 0.99294 (4) | 0.798344 (8) | 0.01869 (6) | |
C1 | 1.1233 (8) | 1.1176 (5) | 0.9028 (5) | 0.0212 (12) | |
O1 | 1.2053 (6) | 1.1868 (3) | 0.9687 (3) | 0.0307 (8) | |
N1 | 0.7925 (6) | 0.8443 (4) | 0.6915 (4) | 0.0218 (9) | |
C2 | 0.8653 (6) | 1.1332 (4) | 0.6881 (4) | 0.0206 (10) | |
O2 | 0.8203 (4) | 1.2112 (3) | 0.6253 (2) | 0.0327 (6) | |
N2 | 0.3021 (3) | 0.5061 (4) | 0.6952 (2) | 0.0230 (6) | |
C3 | 1.2185 (4) | 0.9810 (7) | 0.7074 (2) | 0.0238 (9) | |
O3 | 1.3582 (3) | 0.9783 (5) | 0.6594 (2) | 0.0384 (8) | |
C4 | 1.1080 (9) | 0.8553 (5) | 0.9047 (6) | 0.0233 (12) | |
O4 | 1.1972 (6) | 0.7822 (3) | 0.9596 (3) | 0.0337 (8) | |
C5 | 0.7301 (4) | 1.0112 (5) | 0.8913 (2) | 0.0204 (11) | |
O5 | 0.5952 (4) | 1.0199 (2) | 0.9427 (2) | 0.0327 (8) | |
C6 | 0.7783 (5) | 0.8398 (3) | 0.5751 (3) | 0.0244 (7) | |
H6 | 0.8463 | 0.9017 | 0.5355 | 0.029* | |
C7 | 0.6690 (5) | 0.7487 (3) | 0.5122 (3) | 0.0289 (7) | |
H7 | 0.6611 | 0.7487 | 0.4304 | 0.035* | |
C8 | 0.5703 (5) | 0.6569 (3) | 0.5682 (3) | 0.0245 (7) | |
H8 | 0.4963 | 0.5924 | 0.5258 | 0.029* | |
C9 | 0.5815 (5) | 0.6609 (3) | 0.6876 (3) | 0.0204 (6) | |
C10 | 0.6930 (4) | 0.7558 (3) | 0.7446 (3) | 0.0190 (6) | |
H10 | 0.7001 | 0.7587 | 0.8263 | 0.023* | |
C11 | 0.4868 (5) | 0.5628 (3) | 0.7575 (3) | 0.0204 (6) | |
H11 | 0.4530 | 0.6007 | 0.8312 | 0.025* | |
C12 | 0.6199 (5) | 0.4479 (3) | 0.7839 (3) | 0.0285 (8) | |
H12A | 0.7203 | 0.4626 | 0.8522 | 0.034* | |
H12B | 0.6931 | 0.4261 | 0.7174 | 0.034* | |
C13 | 0.4704 (5) | 0.3435 (4) | 0.8078 (3) | 0.0283 (8) | |
H13A | 0.4955 | 0.2666 | 0.7642 | 0.034* | |
H13B | 0.4821 | 0.3232 | 0.8911 | 0.034* | |
C14 | 0.2606 (5) | 0.3988 (3) | 0.7666 (3) | 0.0246 (7) | |
H14A | 0.1746 | 0.3365 | 0.7210 | 0.030* | |
H14B | 0.1908 | 0.4258 | 0.8329 | 0.030* | |
C15 | 0.1310 (5) | 0.5916 (4) | 0.6783 (3) | 0.0321 (8) | |
H15A | 0.0156 | 0.5494 | 0.6343 | 0.048* | |
H15B | 0.1687 | 0.6655 | 0.6359 | 0.048* | |
H15C | 0.0930 | 0.6174 | 0.7535 | 0.048* |
U11 | U22 | U33 | U12 | U13 | U23 | |
W1 | 0.01884 (8) | 0.01807 (8) | 0.01892 (8) | −0.00160 (9) | 0.00110 (4) | −0.00046 (9) |
C1 | 0.017 (2) | 0.024 (3) | 0.022 (3) | 0.0024 (17) | 0.0021 (17) | 0.0015 (18) |
O1 | 0.0287 (18) | 0.0293 (18) | 0.033 (2) | −0.0064 (14) | 0.0007 (14) | −0.0016 (14) |
N1 | 0.021 (2) | 0.0222 (18) | 0.0211 (18) | 0.0006 (15) | −0.0020 (14) | −0.0023 (12) |
C2 | 0.021 (2) | 0.0141 (18) | 0.025 (2) | 0.0005 (17) | −0.0033 (17) | 0.0001 (13) |
O2 | 0.0357 (14) | 0.0301 (15) | 0.0304 (15) | 0.0040 (12) | −0.0037 (11) | 0.0013 (12) |
N2 | 0.0172 (10) | 0.0248 (18) | 0.0262 (12) | −0.0042 (15) | −0.0002 (8) | 0.0002 (15) |
C3 | 0.0216 (12) | 0.028 (3) | 0.0223 (14) | 0.0030 (19) | 0.0068 (10) | 0.0013 (18) |
O3 | 0.0368 (12) | 0.042 (2) | 0.0386 (13) | 0.0094 (16) | 0.0119 (9) | 0.0142 (15) |
C4 | 0.024 (2) | 0.018 (2) | 0.026 (3) | −0.0011 (18) | −0.0001 (18) | 0.0026 (17) |
O4 | 0.042 (2) | 0.0292 (17) | 0.0269 (19) | −0.0006 (15) | −0.0089 (14) | 0.0064 (14) |
C5 | 0.0202 (12) | 0.022 (3) | 0.0200 (14) | −0.0013 (14) | 0.0070 (10) | −0.0048 (14) |
O5 | 0.0327 (12) | 0.031 (3) | 0.0349 (14) | −0.0026 (10) | 0.0071 (9) | −0.0025 (9) |
C6 | 0.0282 (17) | 0.0266 (19) | 0.0185 (19) | −0.0014 (14) | 0.0029 (13) | 0.0036 (14) |
C7 | 0.0345 (19) | 0.035 (2) | 0.0170 (18) | −0.0022 (15) | 0.0021 (13) | −0.0001 (13) |
C8 | 0.0281 (17) | 0.0268 (18) | 0.0175 (18) | −0.0031 (14) | −0.0016 (12) | −0.0027 (12) |
C9 | 0.0167 (14) | 0.0233 (17) | 0.0209 (18) | 0.0029 (12) | 0.0005 (11) | −0.0001 (12) |
C10 | 0.0199 (15) | 0.0220 (17) | 0.0150 (16) | 0.0017 (12) | 0.0019 (11) | −0.0005 (11) |
C11 | 0.0196 (16) | 0.0228 (18) | 0.0190 (18) | −0.0019 (14) | 0.0025 (11) | −0.0026 (14) |
C12 | 0.0234 (17) | 0.0250 (18) | 0.037 (2) | −0.0056 (13) | 0.0013 (14) | 0.0076 (12) |
C13 | 0.0271 (19) | 0.027 (2) | 0.030 (2) | −0.0056 (13) | 0.0005 (14) | 0.0053 (13) |
C14 | 0.0224 (16) | 0.0218 (17) | 0.0299 (19) | −0.0067 (13) | 0.0039 (13) | −0.0018 (13) |
C15 | 0.0243 (17) | 0.0310 (19) | 0.040 (2) | 0.0035 (14) | 0.0013 (14) | 0.0027 (15) |
W1—C1 | 1.987 (6) | C7—H7 | 0.9500 |
W1—C3 | 2.035 (3) | C8—C9 | 1.388 (5) |
W1—C2 | 2.052 (5) | C8—H8 | 0.9500 |
W1—C4 | 2.055 (6) | C9—C10 | 1.379 (5) |
W1—C5 | 2.064 (3) | C9—C11 | 1.507 (5) |
W1—N1 | 2.278 (4) | C10—H10 | 0.9500 |
C1—O1 | 1.156 (7) | C11—C12 | 1.522 (4) |
N1—C10 | 1.344 (5) | C11—H11 | 1.0000 |
N1—C6 | 1.352 (6) | C12—C13 | 1.539 (5) |
C2—O2 | 1.126 (6) | C12—H12A | 0.9900 |
N2—C15 | 1.451 (5) | C12—H12B | 0.9900 |
N2—C14 | 1.460 (5) | C13—C14 | 1.536 (4) |
N2—C11 | 1.480 (4) | C13—H13A | 0.9900 |
C3—O3 | 1.138 (4) | C13—H13B | 0.9900 |
C4—O4 | 1.132 (7) | C14—H14A | 0.9900 |
C5—O5 | 1.138 (4) | C14—H14B | 0.9900 |
C6—C7 | 1.374 (5) | C15—H15A | 0.9800 |
C6—H6 | 0.9500 | C15—H15B | 0.9800 |
C7—C8 | 1.384 (5) | C15—H15C | 0.9800 |
C1—W1—C3 | 89.8 (2) | C10—C9—C11 | 118.9 (3) |
C1—W1—C2 | 90.6 (3) | C8—C9—C11 | 123.0 (3) |
C3—W1—C2 | 87.9 (2) | N1—C10—C9 | 124.0 (3) |
C1—W1—C4 | 87.75 (12) | N1—C10—H10 | 118.0 |
C3—W1—C4 | 87.7 (2) | C9—C10—H10 | 118.0 |
C2—W1—C4 | 175.3 (2) | N2—C11—C9 | 113.0 (3) |
C1—W1—C5 | 88.7 (2) | N2—C11—C12 | 101.4 (3) |
C3—W1—C5 | 178.1 (3) | C9—C11—C12 | 113.7 (2) |
C2—W1—C5 | 90.97 (18) | N2—C11—H11 | 109.5 |
C4—W1—C5 | 93.4 (2) | C9—C11—H11 | 109.5 |
C1—W1—N1 | 175.2 (2) | C12—C11—H11 | 109.5 |
C3—W1—N1 | 94.2 (2) | C11—C12—C13 | 104.5 (3) |
C2—W1—N1 | 92.12 (11) | C11—C12—H12A | 110.9 |
C4—W1—N1 | 89.8 (3) | C13—C12—H12A | 110.9 |
C5—W1—N1 | 87.30 (16) | C11—C12—H12B | 110.9 |
O1—C1—W1 | 176.2 (5) | C13—C12—H12B | 110.9 |
C10—N1—C6 | 117.2 (4) | H12A—C12—H12B | 108.9 |
C10—N1—W1 | 119.7 (3) | C14—C13—C12 | 104.1 (3) |
C6—N1—W1 | 123.1 (3) | C14—C13—H13A | 110.9 |
O2—C2—W1 | 174.5 (4) | C12—C13—H13A | 110.9 |
C15—N2—C14 | 112.0 (2) | C14—C13—H13B | 110.9 |
C15—N2—C11 | 113.5 (3) | C12—C13—H13B | 110.9 |
C14—N2—C11 | 103.9 (3) | H13A—C13—H13B | 109.0 |
O3—C3—W1 | 177.1 (6) | N2—C14—C13 | 104.9 (3) |
O4—C4—W1 | 173.8 (5) | N2—C14—H14A | 110.8 |
O5—C5—W1 | 179.3 (5) | C13—C14—H14A | 110.8 |
N1—C6—C7 | 122.3 (3) | N2—C14—H14B | 110.8 |
N1—C6—H6 | 118.9 | C13—C14—H14B | 110.8 |
C7—C6—H6 | 118.9 | H14A—C14—H14B | 108.8 |
C6—C7—C8 | 119.8 (3) | N2—C15—H15A | 109.5 |
C6—C7—H7 | 120.1 | N2—C15—H15B | 109.5 |
C8—C7—H7 | 120.1 | H15A—C15—H15B | 109.5 |
C7—C8—C9 | 118.7 (3) | N2—C15—H15C | 109.5 |
C7—C8—H8 | 120.7 | H15A—C15—H15C | 109.5 |
C9—C8—H8 | 120.7 | H15B—C15—H15C | 109.5 |
C10—C9—C8 | 118.1 (3) | ||
C3—W1—C1—O1 | −139 (7) | C1—W1—C5—O5 | −122 (22) |
C2—W1—C1—O1 | 133 (7) | C3—W1—C5—O5 | −159 (22) |
C4—W1—C1—O1 | −51 (7) | C2—W1—C5—O5 | 147 (22) |
C5—W1—C1—O1 | 42 (7) | C4—W1—C5—O5 | −35 (22) |
N1—W1—C1—O1 | 8 (9) | N1—W1—C5—O5 | 55 (22) |
C1—W1—N1—C10 | −11 (3) | C10—N1—C6—C7 | −0.5 (6) |
C3—W1—N1—C10 | 135.7 (3) | W1—N1—C6—C7 | 179.4 (3) |
C2—W1—N1—C10 | −136.2 (3) | N1—C6—C7—C8 | −0.6 (6) |
C4—W1—N1—C10 | 48.1 (3) | C6—C7—C8—C9 | 1.2 (5) |
C5—W1—N1—C10 | −45.3 (3) | C7—C8—C9—C10 | −0.8 (5) |
C1—W1—N1—C6 | 169 (2) | C7—C8—C9—C11 | −177.5 (3) |
C3—W1—N1—C6 | −44.1 (4) | C6—N1—C10—C9 | 1.0 (5) |
C2—W1—N1—C6 | 44.0 (4) | W1—N1—C10—C9 | −178.9 (2) |
C4—W1—N1—C6 | −131.8 (4) | C8—C9—C10—N1 | −0.3 (5) |
C5—W1—N1—C6 | 134.8 (4) | C11—C9—C10—N1 | 176.5 (3) |
C1—W1—C2—O2 | 71 (4) | C15—N2—C11—C9 | −69.3 (3) |
C3—W1—C2—O2 | −18 (4) | C14—N2—C11—C9 | 168.8 (3) |
C4—W1—C2—O2 | 2 (7) | C15—N2—C11—C12 | 168.6 (3) |
C5—W1—C2—O2 | 160 (4) | C14—N2—C11—C12 | 46.7 (3) |
N1—W1—C2—O2 | −113 (4) | C10—C9—C11—N2 | 152.7 (3) |
C1—W1—C3—O3 | −7 (10) | C8—C9—C11—N2 | −30.6 (5) |
C2—W1—C3—O3 | 84 (10) | C10—C9—C11—C12 | −92.4 (4) |
C4—W1—C3—O3 | −94 (10) | C8—C9—C11—C12 | 84.2 (4) |
C5—W1—C3—O3 | 30 (13) | N2—C11—C12—C13 | −35.7 (3) |
N1—W1—C3—O3 | 176 (10) | C9—C11—C12—C13 | −157.3 (3) |
C1—W1—C4—O4 | −71 (5) | C11—C12—C13—C14 | 12.4 (4) |
C3—W1—C4—O4 | 19 (5) | C15—N2—C14—C13 | −162.2 (3) |
C2—W1—C4—O4 | −1 (8) | C11—N2—C14—C13 | −39.3 (3) |
C5—W1—C4—O4 | −159 (5) | C12—C13—C14—N2 | 15.9 (4) |
N1—W1—C4—O4 | 113 (5) |
Experimental details
Crystal data | |
Chemical formula | [W(C10H14N2)(CO)5] |
Mr | 486.13 |
Crystal system, space group | Monoclinic, P21 |
Temperature (K) | 100 |
a, b, c (Å) | 6.6303 (1), 10.6720 (2), 11.6748 (2) |
β (°) | 96.636 (1) |
V (Å3) | 820.56 (2) |
Z | 2 |
Radiation type | Cu Kα |
µ (mm−1) | 13.29 |
Crystal size (mm) | 0.28 × 0.25 × 0.19 |
Data collection | |
Diffractometer | Bruker SMART CCD APEXII area-detector diffractometer |
Absorption correction | Numerical (SADABS; Sheldrick, 2008a) |
Tmin, Tmax | 0.119, 0.185 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 6704, 2676, 2673 |
Rint | 0.020 |
(sin θ/λ)max (Å−1) | 0.596 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.014, 0.033, 1.13 |
No. of reflections | 2676 |
No. of parameters | 210 |
No. of restraints | 1 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.44, −0.53 |
Absolute structure | Flack (1983), 1225 Friedel pairs |
Absolute structure parameter | 0.041 (9) |
Computer programs: APEX2 (Bruker, 2006), SAINT (Bruker, 2005), SHELXTL (Sheldrick, 2008b).
Acknowledgements
We acknowledge the UWC SR for funding and RAL acknowledges support by NSF-CRIF (grant No. 0443538) for the X-ray instrument.
References
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An effort to understand and mimic the nature of nitrogen fixation has led to wide studies on the responsible enzyme, nitrogenase (Jennings, 1991; Schrock, 2006). The focus of our study was to investigate the reactions of the precursor tungsten halocarbonyl derivative, [W(CO)4X2]2, with nitrogen bases to help contribute to this investigation. The compound nicotine (L), was reacted with the presupposed W(CO)4X2, with the hope of obtaining W(CO)4L2; however, the product which was confirmed by a single-crystal X-ray analysis was W(CO)5L, indicating that the compound was formed via a different route. It is thus envisaged that during the preparation of the precursor it is likely that such compounds as W(CO)5Cl- [Abel et al. (1963); Baker (1998)] may be formed, which in turn react with a single molecule of the ligand, nicotine, forming the obtained product. There is less likelihood of a direct substitution of the carbonyl ligands (Tripathi & Srivasatva, 1970) or a redox mechanism (Heyns & Buchholtz, 1976) that would most likely lead to a disubstituted compound. The coordination of nicotine to tungsten, as observed, is via the imine nitrogen as shown in the crystal structure of the compound (See Figure 1).
The W metal centre has cis angles in the range 87.30 (16) to 94.2 (2)°, and trans angles between 175.2 (2)° and 178.1 (4)°. The W–CO bond trans to the nitrogen [1.987 (6) Å] is noticeably shorter than the others, which range between 2.036 (3) and 2.064 (3) Å, possibly due to the known trans effect. The distance between the W atom and the nicotine imine N is 2.278 (4) Å.
The infrared absorption bands of the compound show five absorption peaks at 2006.8(m), 1921.9(w), 1884.3(s), 1816.6(m) and 1760.9(m) cm-1. Also, there is a ~1ppm shift downfield in the positions of the alpha protons on the pyridine ring of the product in both the 1H and 13C NMR spectra compared to the reactants. The CO that is trans to the pyridinyl structure has the most significant shift upfield, possibly due to the trans effect. Only one peak is observed for the carbonyls in the 13C NMR spectrum, possibly due to shielding by the ring electrons leading to a slow decay, and since they are so close they appear identical.