Pseudohalide complexes of palladium(II) containing PCP pincer: Synthesis, characterization, and their antimicrobial activities

Novel pseudohalide complexes of palladium(II) containing the PCP pincer, Pd(PCP)X (PCP = 2,6-(Cy2PCH2)2C6H3, X = OTf (1), N3 (2), NCO (3), NCS (4), SeCN (5)) were prepared. Reaction of Pd(PCP)OTf (1) with corresponding Na(or K)X (X = N3, NCO, NCS, SeCN) in acetone/H2O generated complexes 2–5. The 15N-labeling complex Pd(PCP)(15NCS) was synthesized by the reaction of 1 and KSC15N. Linkage isomerism of complexes 3–5 was discussed on the basis of IR and multinuclear NMR (13C{1H}, 15N{1H} and 31P{1H}) spectroscopic data. Treatment of 2 with CO in benzene afforded 3. The reaction under atmospheric pressure of CO slowly undergoes to give 3 in 12 h, however under higher pressure of CO (5 atm), it proceeds fast to yield 3 in 10 min, quantitatively. Complexes 1–5 were characterized by elemental analyses, IR and multinuclear NMR (1H, 19F{1H}, 13C{1H}, 15N{1H} and 31P{1H}) spectroscopic techniques. The molar conductivity measurements for complexes 1–5 in DMSO reveal that complex 1 is a 1:1 electrolyte whereas 2–5 are non-electrolytes. These complexes in the solid state are intact to air, moisture, and light for ca. 2 months, at least. The title complexes were tested for antimicrobial activity on a wide range of bacterial strains. Complex 1 was found to be potent in this respect.