There are five palladium-cyanomethyl complexes in the CSD, all of which are squareplanar Pd(II) phosphine complexes analogous to 1, but which are neutral, rather than cationic species: three complexes with the formula [Pd(PPh3)2(Cl)(CH2CN)](solvate); [Pd(PCP)(CH2CN)], where PCP is a tridentate pincer ligand with an anionic C atom in the central position; and the bis-cyanomethyl complex [Pd(dppe)(CH2CN)2], where dppe is the diphosphine 1,2-(diphenylphosphino)ethane. The cyanomethyl group is cis to the phosphines in each of these complexes, and the Pd-P distances of approximately 2.29-2.33 Å are nearly identical to the analogous Pd-P2 distances in 1. These distances are also very similar to the Pd-Pterminal distances in [Pd(triphos)X] + complexes with X = Cl, Br, I, NO3, O3SCF3, and N-p-tosyl, all of which range from 2.31-2.34 Å. It is clear that there is no significant cis influence due to the cyanomethyl or any other X ligand. On the other hand, while the Pd-P1 distances in the known [Pd(triphos)X] + complexes are all between 2.19-2.21 Å, indicating that the trans influences of these weak-field ions are all similar, the Pd-P1 distance in 1 is significantly longer, at 2.269(2) Å. This value is closer to those of the known [Pd(triphos)(monophosphine)] 2+ complexes, which are all very nearly 2.30 Å, consistent with the trans influence of the strongly σ-donating cyanomethyl group being stronger than those of the π-donating X ions but less than that of a π-accepting phosphine. For the other trans influence observed in this structure, the Pd-C distance of 2.173(8) Å in 1 is nearly 0.1 Å greater than in the [Pd(PPh3)2(Cl)(CH2CN)] complexes, where the cyanomethyl is trans to the chloride, and slightly longer than the 2.136 Å in [Pd(PCP)(CH2CN)], where it is trans to an anionic carbon atom in the pincer complex. The distance in 1 is very similar to the two Pd-C distances in Pd(dppe)(CH2CN)2, where the C atoms are also trans to the phosphines of the dppe ligand. These distances again point to the very strong trans influence of phosphine donors over even very strongly sigma-donating C-donor atoms and especially over weakfield halides.