Mono- and dinuclear palladium(II) cyclometallates with 4-R-N′-(mesitylidene)benzohydrazides and mono- and diphosphines

Reactions of PdCl2, LiCl, 4-R-N'-(mesitylidene) benzohydrazides (H2Ln; n - 1 and 2 for R - H and OMe, respectively) and NaOAc center dot 3H(2)O in 1: 2: 1: 1 mol ratio in methanol produce [Pd(HLn)Cl] (1 (n = 1) and 2 (n = 2)) in similar to 77% yields. Reactions of [Pd(HLn)Cl] (1 and 2) with PPh3 in 1:2 mol ratio in acetone provide [Pd(L-n)(PPh3)] (3 (n = 1) and 4 (n = 2)) in similar to 76% yields. Whereas, treatment of 2 mol equivalents of [Pd(HLn)(Cl)] (1 and 2) with 1 mol equivalent of 1,4-bis(diphenylphosphino) butane (dppb) in acetone affords the dinuclear [Pd-2(mu-dppb)(L-n)(2)] (5 (n = 1) and 6 (n = 2)) in similar to 74% yields. Analogous reaction between [Pd(HL2)Cl] (2) and 1,1'-bis(diphenylphosphino)ferrocene (dppf) provides [Pd-2(mu-dppf)(L-2)(2)] (7) in 67% yield. Elemental (CHN) analysis, X-ray crystallographic and spectroscopic (IR, UV-Vis and NMR) measurements have been used to characterize all the complexes. In these complexes, the metal centers are in square-planar CNOCl or CNOP coordination geometry formed by the 6,5-membered fused chelate rings forming methylene-C, azomethine-N and amide-or amidate-O donor (HLn) or (L-n)(2) and the ancillary ligand chloride or phosphine. The spectroscopic properties of the complexes are consistent with the corresponding molecular structures established by X-ray crystallography. (C) 2016 Elsevier B. V. All rights reserved.