The high pKa of acetonitrile has led to the development of very strong bases, such as the proazaphosphatrane series of Verkade's bases, N(CH2CH2NR)3P, to generate the active cyanomethide anion as alternatives to n-butyllithium or other harsh and/or dangerous reagents. The strong bases used to deprotonate acetonitrile have limited the catalytic applications, as these bases are often reactive towards the electrophiles that are intended to react with the nucleophilic cyanomethyl group. As a result, many reactions involving direct deprotonation of nitrile substrates have been limited to activated nitriles, and alternative strategies have instead been developed to avoid the need to deprotonate acetonitrile, using activated species such as Me3SiCH2CN. It was previously recognized by Shibasaki that complexation of acetonitrile with a Lewis-acidic metal can stabilize the cyanomethyl species, allowing the weaker base DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) to be used successfully in catalytic amounts in the cyanomethylation of carbonyl compounds catalyzed by [CpRu(PPh3)(MeCN)2] + ; 17,18 a similar reaction using a nickel-pincer catalyst was reported by Ozerov. However, the degree of acidification of acetonitrile using transition-metal Lewis acids has not been quantified, and the cyanomethyl species are proposed to form in catalytic amounts as reactive intermediates. To the best of our knowledge, and as recently reviewed by Bissember et al, stoichiometric deprotonation of acetonitrile to form a metal-cyanomethyl complex has been achieved only using hydroxide, alkoxide, or even stronger bases such as n BuLi. Lopez and Palomo ended their recent review of cyanoalkylation chemistry by emphasizing that "[i]n the context of metal-assisted deprotonation of alkylnitriles, predicting the ability of different metals to activate the nitriles towards deprotonation of the resultant complexes is difficult and thus research on this aspect would facilitate the design of new and more-efficient catalyst systems." The guanidine and phosphazene bases used to generate the cyanomethyl species in this work have well-characterized pKa BH+ values that are orders of magnitude less than free acetonitirle. As a result, they demonstrate that acetonitrile becomes more acidic by at least 8 pKa units in the presence of the palladium-triphos and -PNP complexes here, with the uncertainty in the actual values being due to difficulties in establishing the pKa of free acetonitrile itself.