Synthesis, characterization and structural studies of new palladium(II) complexes including non-symmetric phosphorus ylides

A palladium–phosphine catalytic system as an active and recycable precatalyst for Suzuki coupling in water

“…A single anodic peak (A L1 ) was observed on the reverse scan. This behavior is similar to that reported previously by Champness et al [37], Batchelor et al [38], Downard et al [39] and our group [40][41][42] in cyclic voltammetric studies of various types of Pd(II) complexes The cathodic peak C M1 at 1.05 V versus the Ag/AgCl reference electrode can be assigned to the formation of a Pd(0) center with a coordination number between 2 and 4 [or alternatively to an equilibrium mixture of several Pd(0) species] [39,[43][44][45]. There are some examples of stable Pd(0) complexes; particularly relevant is [Pd(L) 2 ] 0 (L = 1,2-bis(dimethylarsino)benzene), which is sufficiently stable to be isolated as a solid [46].…”

Four-coordinate Pd(II) complexes containing non-symmetric phosphorus ylides: Synthesis, characterization, and catalytic behavior towards Suzuki reaction

“…In the 31 P NMR spectra the signal due to PCH appears as a broad signal for 2 and doublets for 1 and 3e5. The significant downfield shift of these signals from that of the free ylides are in agreement with the C-bonding of the ylides [43,45]. The coordination via the phosphine moiety is also clearly evidenced from the strong downfield shifts of the signals due to PPh 2 group when compared to that of the same signal in the free ylides [4,11].…”

“…Coordination of the ylides through C-coordination causes an increase in n(CO) [41e43] while for O-coordination a lowering of n(CO) is expected [44]. Thus, the IR data obtained indicates that the interaction of the ligands with palladium(II) chloride are through the ylidic carbon atom and PPh 2 group [5,45], as proved by the crystal structure of 1 (vide infra).…”

Seven-membered Pd(II) complexes containing symmetric phosphorus ylides: Synthesis, characterization and high catalytic activity toward Suzuki cross-coupling reactions

“…This chemical shift is at a lower field than that observed for the corresponding free ylide (around 15 ppm), indicating that the coordination of the ylides has occurred. As reported earlier [17,40], the downfield shift of the ylidic phosphorus signifies the coordination of the ylidic moiety. The coordination of the bis-ylides 4-6 to the palladium center creates two stereogenic centers of the same configuration, as indicated by the presence of two 31 P NMR signals (doublets with a coupling constant 3 J P-P of 2-7 Hz).…”

“…In the 1 H NMR spectra, the signals due to the methinic protons for all the complexes are broad and centered at 5-6 ppm. The 1 H chemical shift values for the complexes appear to be shifted downfield with respect to the parent ylide, indicating also that the coordination of the ylides has occurred [40,41]. Selected NMR chemical shifts for compounds 1-9 are reported in Table 2.…”