Bis(Methallyl)di-chloro-dipalladium(II) (See Page 50),
Sodium dimethyl malonate (See procedure below),
1,3-Bis-(2,6-diisopropylphenyl)imidazolin-2-ylidene (See Page 34),
THF (heated at reflux over potassium for three days then distilled and stored in an ampoule over sieves),
Toluene (heated at reflux over sodium for three days then distilled and stored in an ampoule over sieves or a potassium mirror).

Synthesis of sodium dimethylmalonate: A THF (10 mL) slurry of NaH (654 mg, 27 mmol) was added dropwise to a cooled (0 ^oC) solution of dimethylmalonate (3.00 g, 23 mmol) in THF (20 mL) under an inert atmosphere. The mixture was warmed to ambient temperature with stirring over 1 h under an oil bubbler presure of argon to allow venting of the H₂ under an inert atmosphere. The mixture was then filtered through Celite on a frit into a Schlenk tube. The solvent was removed in vacuo to yield a sticky white solid. The solid was dried by heating at 50 ^oC under vacuum (1x10^-2 mbar) for 6 h (3.07 g, 88% yield). A ¹H nmr spectrum of the dried solid showed no THF to be present. Synthesis of bis(1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene)palladium(0): 1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene (792 mg, 2.03 mmol), bis(methallyl)di-chloro-dipalladium(II) (200 mg, 0.508 mmol) and sodium dimethylmalonate (157 mg, 1.02 mmol) were placed in an ampoule with a teflon stopcock in a glove box. The ampoule was sealed and removed from the glove box. The ampoule was attached to a double manifold Schlenk line and fitted with a septum. THF (40 mL) was added via canula and the ampoule sealed. The mixture was heated at 60 ^oC for 16 h with stirring after which the solution was bright orange. The solvent was removed in vacuo and the product extracted with toluene (3 x 20 mL). The extracts were combined and filtered through Celite on a frit. The toluene solution was concentrated and cooled to –50 ^oC to yield an orange crystalline solid. The filtrate was removed via cannula and the product washed with cold toluene (3 x 5 mL). The solid was dried under vacuum (1x10^-2 mbar) to yield the product as an orange crystalline solid (567 mg, 63 % yield).

Standard Schlenk line techniques were used for all manipulations involved in the procedures described on this page and for subsequent usage of the bis carbene palladium complex (see ref 1). However, the solid palladium complex is stable to air for short periods of time. For example, the complex can be exposed to air whilst weighing portions of it. The storage and reaction vessels should be air tight and placed under an inert atmosphere after exposure to air. This is easily achieved by attaching the vessels to a double manifold and cycling the vessels vacuum/argon three times. The synthesis of the palladium carbene complex has been performed 4 times on a scale of 0.2 g to 2.4 g of methallyl palladium chloride dimer.

¹H NMR (d₆-benzene) 1.20 (d, 24H, ⁱPr-CH₃, ³J(HH) = 6.9 Hz), 1.21 (d, 24H, ⁱPr-CH₃, ³J(HH) = 6.9 Hz), 3.11-3.14 (m, 8H, ⁱPr-CH, ³J(HH) = 6.9 Hz), 3.12 (s, 8H, NCH2CH2N), 7.07 (d, 8H, Ar-m-CH, ³J(HH) = 7.7 Hz), 7.24 (t, 4H, Ar-p-CH, ³J(HH) = 7.7 Hz). ¹³C{¹H} NMR (d₆-benzene) 24.2 (ⁱPr-CH₃), 25.7 (ⁱPr-CH₃), 28.7 (s, ⁱPr-CH), 53.4 (NCH2CH2N), 124.0 (Ar-CH), 128.0 (Ar-CH), 139.6 (Ar-C), 146.9 (Ar-C), 218.5 (NCN).

See supplementary information for: Titcomb, L. R.; Caddick, S.; Cloke, F. G. N.; Wilson, D. J. W.; McKerrecher, D. Chem. Commun., 2001, 1388.

1. Shriver, D. F.; The Manipulation of Air Sensitive Compounds, McGraw-Hill, New York, 1989. 2. Caddick, S.; Cloke, F. G. N.; Clentsmith, G. K. B.; Hitchcock, P. B.; McKerrecher, D.; Titcomb, L. R.; Williams, M. R. V. J. Organomet. Chem., 2001, 617, 635.