Bis(phosphine)-Pd(II) and -Pt(II) complexes containing chiral tetrazole-thiolato rings: Synthesis, structures, and reactivity toward some electrophiles

Azide Chemistry – An Inorganic Perspective, Part II[‡][3+2]‐Cycloaddition Reactions of Metal Azides and Related Systems

“…Moreover, the structural analyses of the resulting tetrazole-thiolato complexes revealed syn and/or anti conformations of the S-bound tetrazole rings. [390] Scheme 16 presents an array of the more unusual co-ligands employed in those studies. With the exception of the dianionic bridging ligand bithienylene (μ-{C} 2 ), all the other species resulted from cyclopalladation reactions acting either as bi-({C,N} I-IV ) or tridentate C,N-donor chelate ligands ({C,N,N}) or just as a σ-bonded monodentate η 1 -C-ligand (Table 4).…”

“…This has been interpreted as initial stage of a reaction pathway ultimately generating an η 5 -CN 4 -Pb interaction. [196] The above-mentioned discrepancy between the calculations of the relative stabilities of the two possible linkage isomers VI and VII (Scheme 15) which clearly favour N 4 coordination, [56] and the recent accumulated experimental evidence of 'S-coordination without exception', [52,53,55,60,61,64,65,[390][391][392][396][397][398] has been resolved by a detailed study of the reaction mechanisms. [56] According to that, a two-step process occurs in which the isothiocyanate Satom first approaches the metal with simultaneous attack by the azide N α -on the isothiocyanate C-atom to give an intermediate S-bonded imidoyl azide, XVI, strongly reminiscent of the imidoyl azide intermediate previously found in the theoretical study on the mechanism of azidometal to nitrile [3+2]-cycloadditions (cf.…”

“…Kim et al looked into the reactivity of tetrazole-thiolatopalladium complexes toward several electrophiles in more detail; this included reactions of trans-[Pd{SCN 4 R} 2 (PMe 3 ) 2 ] (R = Ph, 2,6-Me 2 C 6 H 3 , S-(+)-1-phenylethyl) with HCl, benzoyl chloride and 2-thiophenecarbonyl chloride to give the respective organic sulfides (thioacyl compounds) in high yield. [52,390] [142,171] In several cases, however, products were isolated which may well derive from heterocycles forming temporarily, examples being the isocyanato complexes M(NCO) 2 (PPh 3 ) 2 (M = Pd, Pt) and [Pd 2 (μ-N 3 )(μ-NCO)(dmba) 2 ] from the reactions of the corresponding azido complexes with MeNCO or CO 2 (under pressure); [372] for the cyano complexes Pd(CN) 2 (PPh 3 ) 2 and Co(CN)(DH) 2 (NCSMe) to result from reactions with MeSCN, on the other hand, a different process must have been causal (Table 4). [142,171,184] Frequently reactions were indicated by the disappearance of the strong IR band of the antisymmetric azide stretching vibration at about 2050 cm -1 , yet the products obtained were ill-defined or contained no metal at all.…”

New palladium (II) complexes with 1‐phenyl‐1H‐tetrazole‐5‐thiol and diphosphine Synthesis, characterization, biological, theoretical calculations and molecular docking studies

“…Thione compounds are adaptable ligands capable of bonding to transition metal chemistry and non‐transition metals, and the coordinate to transition metals in a wide range of oxidation state. [ 1–18 ] Thione ligands have the facility to stabilize both low and high oxidation state of metal ions, and this mostly due to the approval of thiol and thione tautmers (Chart 1). [ 1 ]…”

“…The thiol‐substituted heterocycle ligand, 1‐phenyl‐tetrazole‐5‐thiol (Hptt), having one soft donor sulfur and three hard donor nitrogen atoms, is a tetrazole‐based heterocyclic thioamide, providing more coordination sites for metal ions to form metal coordination complexes, most commonly, as monodentate ligands through the sulfur or nitrogen atom and can coordinated as bidentate chelating fashion through the sulfur and nitrogen atoms, or mode and bidentate bridging mode through the sulfur and nitrogen atoms, or through the sulfur atom only, as bridge between two metals atoms. Recently, many studies were published including complexes of tetrazole‐5‐thiol ligand with metal ions, [ 2–18 ] or with mixed ligand complexes of tetrazole‐5‐thiol with phosphine or amine as co‐ligands. [ 6–11,19–26 ] Transition metal complexes of tetrazole‐5‐thione present a wide range of applications in agriculture, medicine, industry, analytical and organic chemistry, as antibacterial, anti‐fungal, and anti‐inflammatory.…”