Halide LigandssMore Than Just σ-Donors?
with Perdew’s gradient correction to local density approximation
with VWN parametrization of electron gas data was used (ADF/
BP).23,24 The scalar relativistic zero-order regular approximation
was used in ADF. Within Gaussian 03, polarized valence double-ꢂ
basis sets25 were used for C, N, H and X atoms and for Ni.26 The
hybrid Becke’s three-parameter functional with the Lee, Yang, and
Parr correlation functional (B3LYP)23 was used in Gaussian 03
calculations (G03/B3LYP). The conductor-like polarizable con-
tinuum model (CPCM)27 was used for modeling of the solvent
influence in TD DFT calculations. The calculations on complexes
were performed without any symmetry constraints. Spectral calcula-
tions were done at optimized geometries using an identical method.
Yield: 0.43 g, 0.926 mmol, 60%. Anal. calcd for C19H19IN2Ni
(460.95): C, 49.50; H, 4.15; N, 6.08. Found: C, 49.81; H, 4.25; N,
1
6.11%. H NMR (acetone-d6): See Table 2.
Preparation of [(bpy)Ni(Mes)(OMe)]. A total 100 mg of solid
sodium (4.35 mmol)] was dissolved in 50 mL of terahydrofuran
(THF) and 10 mL of methanol. To this solution was added 400
mg (0.966 mmol) of [(bpy)Ni(Mes)Br], the resulting solution was
stirred for 12 h. The reaction mixture was evaporated to dryness,
and the dark residue was extracted with 5 × 20 mL of dichlo-
romethane. After evaporation of the solvent, the resulting material
was twice recrystallized from dichloromethane/n-heptane (1:1) to
yield 290 mg (0.79 mmol, 82%) of violet microcrystalline material.
Anal. calcd for C20H22O1N2Ni (365.12): C, 65.79; H, 6.07; N, 7.67.
Preparation of the Precursor Complexes trans-[(PPh3)2-
Ni(Mes)X]. The precursor complexes trans-[(PPh3)2Ni(Mes)X] (X
) Cl or Br) were prepared from anhydrous NiX2, PPh3, and
corresponding Grignard reagents MesMgX, as recently described
for trans-[(PPh3)2Ni(Mes)Br].12 trans-[(PPh3)2Ni(Mes)Cl] was ob-
tained as a yellow powder, yield 17%. Anal. calcd for C45H41ClNiP2
(737.92): C, 73.25; H, 5.60. Found: C, 73.31; H, 5.65%. 1H NMR
(CD2Cl2): δ 7.47 (m, 12H, o-Ph); 7.33 (m, 6H, p-Ph); 7.22 (m,
12H, m-Ph); 5.79 (s, 2H, HMes); 2.34 (s, 6H, o-CH3); 1.89 (s, 3H,
p-CH3). 31P NMR (CD2Cl2): δ 18.67. 13C NMR (CD2Cl2): δ 142.1
(Mes1), 142.3 (Mes2), 135.2 (Ph2), 133.2 (Mes4), 132.5 (Ph1),
130.0 (Ph4), 128.0 (Ph3), 127.5 (Mes3), 26.1 (o-CH3), 19.9 (p-
CH3).
1
Found: C, 65.72; H, 5.99; N, 7.71%. H NMR (acetone-d6): See
Table 2; for the OCH3 protons, a signal was found at 3.29 ppm (s,
3H). 13C NMR (acetone-d6): δ 156.5 (bpy2), 153.5 (bpy2′), 153.1
(bpy6), 151.7 (bpy6′), 148.6 (Mes1), 143.5 (Mes2), 139.8 (bpy4),
137.9 (bpy4′), 133 (Mes4), 127.4 (bpy3), 126.7 (bpy3′), 126.2
(Mes3), 122.6 (bpy5), 121.3 (bpy5′), 49.6 (OCH3), 25.8 (o-CH3),
20.9 (p-CH3). UV-vis (acetone): 468, 540sh nm.
Preparation of [(bpy)Ni(Mes)(SCN)]. To a total of 158 mg
(0.38 mmol) of [(bpy)Ni(Mes)Br] dissolved in 50 mL of THF was
added 131 mg (0.38 mmol) of AgSbF6, and the resulting solution
was stirred in the dark for 90 min. The colorless solution obtained
from careful filtration was added to 37 mg (0.38 mmol) of KSCN
suspended in 10 mL of THF. The mixture was heated under reflux
for 3 h. The resulting orange solution was separated from some
colorless precipitate and evaporated to dryness. Recrystallization
from dichloromethane gave 121 mg (0.308 mmol, 81%) of orange-
red material. Anal. calcd for C20H19S1N3Ni (392.16): C, 61.26; H,
Preparation of the Complexes [(bpy)Ni(Mes)X] (X ) F,
Cl, Br, I). The complexes with X ) Cl or Br were synthesized by
stirring the precursor complexes trans-[(PPh3)2Ni(Mes)X] (typically
1.38 g, 1.87 mmol for X ) Cl) with bpy (310 mg, 1.964 mmol) in
diethyl ether (100 mL) at ambient temperature for 24 h. The
resulting dark red suspensions were filtered; the collected precipitate
was rinsed with n-pentane (50 mL) and dried under a vacuum. The
yield for X ) Cl was 0.57 g, 1.543 mmol, 83%. Anal. calcd for
C19H19ClN2Ni (369.52): C, 61.76; H, 5.18; N, 7.58. Found: C,
1
4.88; N, 10.72. Found: C, 61.22; H, 4.89; N, 10.81%. H NMR
(acetone-d6): See Table 2. 13C NMR (acetone-d6): δ 157.9 (bpy2),
155.4 (bpy2′), 151.8 (bpy6), 149.6 (bpy6′), 147.2 (Mes1), 141.7
(Mes2), 141.2 (bpy4), 140.4 (bpy4′), 131.2 (Mes4), 128.2 (bpy3),
128.0 (bpy3′), 126.9 (Mes3), 123.0 (bpy5), 119.3 (bpy5′), 112.1
(SCN), 24.9 (o-CH3), 20.7 (p-CH3). UV-vis (acetone): 445 nm.
IR (film): 2921s, 2098vs (νN≡C f SCN is S-bonded), 1730m,
1604m, 1442s, 1143m, 1013 m, 852m, 765s, 736s cm-1. The
compound was first mentioned in a report by Seidel in 1985,28 but
characterization remained undone.
1
61.81; H, 5.25; N, 7.61%. H NMR (acetone-d6): See Table 2.
[(bpy)Ni(Mes)Br] was obtained under the same conditions at 95%
yield. Anal. calcd for C19H19BrN2Ni (431.98): C, 55.12; H, 4.63;
1
N, 6.77. Found: C, 55.33; H, 4.65; N, 6.72%. H NMR (acetone-
d6): See Table 2.
Preparation of [(bpy)Ni(Mes)F]. To a solution of [(bpy)Ni-
(Mes)Br] (0.99 g, 2.391 mmol) in 1,2-dichloroethane (30 mL) was
added TlF (0.70 g, 3.133 mmol), and the resulting solution was
stirred at 60 °C for 18 h. The mixture was concentrated under a
vacuum to 10 mL, filtered, and treated with n-pentane (60 mL) to
precipitate the product. Yield: 310 mg, 0.878 mmol, 37%. Anal.
calcd for C19H19FN2Ni (353.08): C, 64.63; H, 5.42; N, 7.93. Found:
Results and Discussion
Preparation and Analyses. The complexes [(bpy)Ni-
(Mes)X] (X ) Cl, Br) were prepared from trans-
[(PPh3)2Ni(Mes)X] and bpy as described for X ) Br.12,14
The complexes [(bpy)Ni(Mes)X] (X ) F or I) were obtained
from [(bpy)Ni(Mes)Br] by a salt metathesis reaction using
TlF or NaI, respectively. The complexes with X ) OMe or
SCN were prepared by abstraction of Br from the bromide
complex using AgSbF6 and the addition of the corresponding
anion (KSCN or NaOMe). All complexes were obtained as
air-stable bright red microcrystalline material in good yields.
For long-time storage, the complexes have to be saved from
1
C, 64.70; H, 5.45; N, 7.94%. H NMR (acetone-d6): See Table 2.
19F NMR (acetone-d6): δ -407.1 (s).
Preparation of [(bpy)Ni(Mes)I]. A solution of [(bpy)Ni(Mes)Cl]
(0.57 g, 1.543 mmol) and dry NaI (1.16 g, 7.713 mmol) in dry
acetone (20 mL) was refluxed for 20 h. All volatile parts were
removed under a vacuum, and the solid residue was extracted with
1,2-dichloroethane. Upon the addition of n-pentane (70 mL), a dark
red precipitate formed that was filtered and dried under a vacuum.
1
humidity. From elemental analyses and H NMR spectros-
(23) (a) Becke, A. D. J. Chem. Phys. 1993, 98, 5648–5652. (b) Becke,
A. D. Phys. ReV. A 1988, 38, 3098–3100.
(24) (a) Perdew, J. P.; Burke, K.; Ernzerhof, M. Phys. ReV. Lett. 1996, 77,
3865–3868. (b) Perdew, J. P. Phys. ReV. A 1986, 33, 8822–8824.
(25) Hariharan, P. C.; Pople, J. A. Theor. Chim. Acta 1973, 28, 213–222.
(26) Rassolov, V. A.; Pople, J. A.; Ratner, M. A.; Windus, T. L. J. Chem.
Phys. 1998, 109, 1223–1229.
copy, the entity and high-purity of the obtained materials is
evident (details in the Experimental Section). The fluoride
coligand reveals a 19F NMR signal at -407 ppm, which is
typical for F ligands in square-planar organonickel(II)
(27) Cossi, M.; Rega, N.; Scalmani, G.; Barone, V. J. Comput. Chem. 2003,
24, 669–681.
(28) Seidel, W. Z. Chem. 1985, 25, 411–412.
Inorganic Chemistry, Vol. 47, No. 23, 2008 11327