Arancha Carbayo

Synthesis and Structure of an Asymmetric Binuclear Phenylhydrazonato Anionic Complex of Palladium Containing a Pd−C(aryl) Bondcis to a Pd−N(amido) Bond

The synthesis and structure of a unique asymmetric folded binuclear anionic complex of palladium containing two different hydrazonato ligands and showing a Pd−N(amido) bond cis to a Pd−C(aryl) bond is described.

Revealing the diastereomeric nature of pincer terdentate nitrogen ligands 2,6-bis(arylaminomethyl)pyridine through coordination to palladium

Palladium complexes of formula [PdLCl]X (X = Cl 1, BF42) containing the pincer terdentate ligands L [L = 2,6-(ArNHCH2)2C5H3N (Ar = 4-MeC6H41a and 2a, 4-MeOC6H41b and 2b); L = 2,6-(4-MeC6H4NMeCH2)2C5H3N 1c and 2c] have been synthesised as cis–trans diastereomeric mixtures. The chiral nature of both amine arms of the pincer ligands accounts for the mixtures of isomers. All the complexes show dynamic behavior assigned to conversion between diastereomers. A ΔG‡273 of 68.9 kJ mol−1 for 2a and a ΔG‡273 of 65.8 kJ mol−1 for 2c were found through complete DNMR line-shape analysis of the –CH2– signals in the 1H spectra. The cis–trans conversion requires the inversion of the pyramidal nitrogen of one of the coordinated amine arms. Two putative pathways have been proposed for such inversion: a) dissociation of one of the amine nitrogen atoms followed by inversion of the nitrogen atom and reformation of the nitrogen–palladium bond and b) deprotonation of one of the N–H bond leading to an amido intermediate which can reprotonate on the other side. Experimental evidence is given for both mechanisms. The structural characterization of 1a is described.

Unexpected orthopalladation of acetophenonephenylhydrazone

Abstract A singular hydrazonato complex of palladium has induced the unexpected orthometallation of acetophenonephenylhydrazone on the phenyl group. This is the first X-ray characterized example of an orthopalladated E-arylhydrazone of general formula ArC(R″)NNHAr′ where the metallated aryl is Ar′ although palladation on Ar is not hindered. Structural evidence suggests that the PdN(amido) bond that is present in the starting material induced the palladation of the unexpected phenyl.

Strong Influence of the Ancillary Ligand over the Photodynamic Anticancer Properties of Neutral Biscyclometalated Ir(III) Complexes Bearing 2-Benzoazole-Phenolates

In this paper, the synthesis, comprehensive characterization and biological and photocatalytic properties of two series of neutral IrIII biscyclometalated complexes of general formula [Ir(C^N)2 (N^O)], where the N^O ligands are 2-(benzimidazolyl)phenolate-N,O (L1, series a) and 2-(benzothiazolyl)phenolate-N,O (L2, series b), and the C^N ligands are 2-(phenyl)pyridinate or its derivatives, are described,. Complexes of types a and b exhibit dissimilar photophysical and biological properties. In vitro cytotoxicity tests conclusively prove that derivatives of series a are harmless in the dark against SW480 cancer cells (colon adenocarcinoma), but express enhanced cytotoxicity versus the same cells after stimulation with UV or blue light. In contrast, complexes of type b show a very high cytotoxic activity in the dark, but low photosensitizing ability. Thus, the ancillary N^O ligand is the main factor in terms of cytotoxic activity both in the dark and upon irradiation. However, the C^N ligands play a key role regarding cellular uptake. In particular, the complex of formula [Ir(dfppy)2 (L1)] (dfppy=2-(4,6-difluorophenyl)pyridinate) [3 a] has been identified as both an efficient photosensitizer for 1 O2 generation and a potential agent for photodynamic therapy. These capabilities are probably related to a combination of its notable cellular internalization, remarkable photostability, high photoluminescence quantum yield, and long triplet excited-state lifetime. Both types of complexes exhibit notable catalytic activity in the photooxidation of thioanisole and S-containing aminoacids with full selectivity.

A phosphino-substituted isoindole obtained by cyclization of a thiourea derivative

A phosphorous functionalized isoindole derivative has been formed in the cyclization reaction of 3-chloro-p-tolylmethylene-1,1-diethylthiourea with lithium diphenylphosphide. The reaction involves thiourea desulfuration and C-S to P-S sulfur transfer.