Synthesis and characterization of ruthenium heterocyclic-thiocarboxylate complexes

The cyclopentadienyl ruthenium complexes CpRuL₂SCO-het (Cp = η⁵-C₅H₅; L₂ = 2PPh₃ (1), dppe (2)) bearing heterocyclic thiocarboxylate ligands have been synthesized from the reaction of CpRuL₂SH with heterocyclic acid chlorides (ClCO-2-C₄H₃S (a); ClCO-2-C₄H₃O (b); ClCO-1-C₄H₈N (c)). Bubbling of CO gas through a THF solution of (1) produced the mixed carbonyl–phosphine complexes CpRu(PPh₃)(CO)SCO-het (3) with high yields. Complexes (1)-(3) were characterized by spectroscopic methods (i.r., ¹H-n.m.r., ³¹P-n.m.r.) and elemental analysis. The molecular structure of CpRu(PPh₃)₂SCO-2-C₄H₃S (1a) verifies that the thiocarboxylate ligands bind via the sulfur atom (Ru–S = 2.406(2) Å).     

Crystallographic and computational study of the structure of copper(II) 2,2′-bis(2-oxidobenzylideneamino)-4,4′-dimethyl-1,1′-biphenyl

The reaction of M(OAc)₂ with 2,2′-bis(2-hydroxybenzylideneamino)-4,4′-dimethyl-1,1′-biphenyl (H₂L1) allows the synthesis of 2,2′-bis(2-oxidobenzylideneamino)-4,4′-dimethyl-1,1′-biphenyl complexes of Cu(II) (CuL1), Co(II) (CoL1) and Ni(II) (NiL1) that were characterized by elemental analysis, FTIR spectroscopy and for CuL1 also by X-ray crystallography verifying a tetradentate binding mode of L1 via an (ONNO) motif of the two phenolic oxygen atoms and two azomethine nitrogen atoms. Recrystallization from a solvent mixture of dichloromethane and methanol promotes the formation of methanol adducts. Different binding modes of the methanol–complex were investigated using density functional theory calculations and binding energies, and thermodynamic data of the interaction are reported. The results show that the favored interaction occurs when the methanol molecule acts as a Lewis acid weakly binding via an O–H···O hydrogen bridge to a phenoxide moiety leading to an elongation of the respective M–O bond.