trans-Bis[1,3-bis(2,4,6-trimethylphenyl)imidazolidin-2-ylidene]dichloronickel(II)
611
Syn th esis of trans-Bis[1,3-bis(2,4,6-trim eth ylph en yl)im idazolidin -2-yliden e]-
dich loron ickel(II) (1)
A solution of LiFlu in THF (1.2 cm 3, 1.22 m m ol) was added at on ce to a suspen sion of
[NiBr2(dm e)2] (0.188 g, 0.61 m m ol) in THF at –78 °C. Th e reaction m ixture was slowly
h eated to room tem perature. Th e resultin g brown solution was stirred for 30 m in an d th en
1,3-bis(2,4,6-trim eth ylph en yl)im idazolidin ium ch loride [SIMesH]+Cl– (0.21 g, 0.61 m m ol)
was added in on e portion . Th e oran ge reaction m ixture was stirred for an oth er 24 h . Th e
solven t was rem oved un der reduced pressure. Th e crude product was extracted with toluen e
(3 × 20 cm 3). Th e extract was con cen trated an d left stan din g for crystallization at 0 °C, af-
fordin g 0.27 g (0.366 m m ol, 60%) of 1. 1H NMR (C6D6, 25 °C): 6.96 (s, 8 H, arom . H); 2.86
(s, 8 H, NCH2); 2.43 (s, 12 H, p-CH3); 2.26 (s, 24 H, o-CH3). 13C NMR: 19.48, o-CH; 21.3,
p-CH3; 50.39, NCH2; 129.76, C-3,5; 136.15, C-2,6; 137.09, C-4; 137.53, C-1; 200.12, NCN.
EI-MS, m/z (rel.%) (58Ni): 740 (M+, 8), 341 ([Cl(NHC) – H]+, 91), 305 ([NHC]+, 22), 277
([C19H21N2]+, 1), 158 ([C10H10N2]+, 2), 146 ([C9H10N2]+, 5), 119 ([C9H11]+, 1), 91 ([C7H7]+, 1).
HRMS: calculated for C42H5235Cl2N458Ni: 740.29225; foun d: 740.29125. Crystals suitable for
X-ray diffraction m easurem en ts were grown from a toluen e solution at 0 °C.
Reaction of [Ni(Flu)2] with PPh 3 an d CCl4
Solution of LiFlu in THF (2 cm 3, 0.35 m m ol) was added at on ce to th e suspen sion of [NiBr2-
(dm e)2] (0.055 g, 0.178 m m ol) in 4 cm 3 THF at room tem perature. To a brown solution
form ed, triph en ylph osph in e (0.046 g, 0.178 m m ol) an d CCl4 (0.1 cm 3, 0.16 g, 1.04 m m ol)
were added after 5 m in . Th e reaction h as been carried out for 1 h an d th en th e solven t was
rem oved un der reduced pressure. Th e solid was wash ed with h exan e (3 × 20 cm 3) an d th en
extracted with toluen e. 0.07 g of [NiCl2(PPh 3)2] (5.6 m m ol, 53%) was obtain ed. M.p. 245–
246 °C (dec.); lit.28 gives 247–250 °C (dec.). Broad sign als appeared in 1H NMR spectrum
owin g to param agn etism of th e com poun d. Th e spectrum is in good agreem en t with th e lit-
erature data29 1H NMR (C6D6, 25 °C): 18.36 (broad s, 2 H, H-2,6); –0.88 (broad s, 2 H, H-3,5);
.
–6.12 (broad s, 1 H, H-4).
Crystal Structure Determ in ation of 1
Crystal data, data collection an d refin em en t param eters for trans-[NiCl2(SIMes)2] (1) are
given in Table I. Th e m olecular structure of th is com poun d is presen ted in Fig. 1. Selected
bon d len gth s an d an gles are sh own in th e figure.
CCDC 639131 (1) con tain s th e supplem en tary crystallograph ic data for th is paper. Th ese
th e Cam bridge Crystallograph ic Data Cen tre, 12, Un ion Road, Cam bridge, CB2 1EZ, UK;
fax: +44 1223 336033; or deposit@ccdc.cam .ac.uk).
Th e crystal was m oun ted on to a glass fiber an d th en flash -frozen to 100 K (Oxford
Cryosystem –Cryostream Cooler). Prelim in ary exam in ation an d in ten sity data collection were
carried out on a Kum a KM4CCD κ-axis diffractom eter with graph ite-m on och rom atized
MoKα radiation . Th e data were corrected for Loren tz, polarization an d absorption effects.
Data reduction an d an alysis were carried out with th e Kum a diffraction (Wrocław, Poland)
program s30. Th e structures were solved by direct m eth ods an d refin ed by th e full-m atrix
least-squares m eth od on all F2 data usin g th e SHELXTL program 31. Th e carbon -bon ded
h ydrogen atom s were in cluded in th e calculated position s an d refin ed usin g a ridin g m odel.
Collect. Czech. Chem. Commun. 2007, Vol. 72, Nos. 5–6, pp. 609–617