Organotin adducts with pyrimidinethione: crystal structure of dimethyldi(pyrimidine‐2‐thiolato)tin(IV) and diphenyldi(pyrimidine‐2‐thiolato)tin(IV)

The complexes dimethyldi(pyrimidine‐2‐thiolato)tin(IV) ( 1 ) and diphenyldi(pyrimidine‐2‐thiolato)tin(IV) ( 2 ) have been structurally ­characterized by means of X‐ray crystallography. Complex 1 exhibits strong π–π stacking interactions and adduct 2 is self‐assembled via intermolecular hydrogen bonds, C H–π and π–π stacking interactions. Partial solvolysis occurs in organic solvents for 1 and 2 . Copyright © 2000 John Wiley & Sons, Ltd.     

Microwave-promoted Suzuki-Miyaura cross-coupling of aryl halides with phenylboronic acid under aerobic conditions catalyzed by a new palladium complex with a thiosemicarbazone ligand

A new air- and moisture-stable palladium complex with salicylaldehyde N(4)-hexamethyleneiminylthiosemicarbazone has been synthesized. According to its crystal structure, the metal is bonded to 2 equiv monoanionic thiosemicarbazone moieties in a N,S-bidentate fashion, forming two five-membered chelate rings, while additional intramolecular bonds stabilize the structure. In contrast to other palladium complexes with thiosemicarbazones, this complex was inactive towards the Suzuki-Miyaura coupling under aerobic conditions, by conventional heating. On the other hand, microwave irradiation promoted the effective catalytic activity of the complex for the coupling of aryl bromides and chlorides with phenylboronic acid in DMF/H₂O, under aerobic conditions, with turnover numbers of up to 37,000.     

Spectrofluorimetric determination of magnesium in blood serium with calcein blue

Magnesium was determined in blood serum by fluorimetry with calcein blue (CB) in alkaline solution (0.01 M KOH). Four separate procedures for masking of iron, copper, zinc and calcium were applied. Complete masking was obtained with a mixture of ethylene glycol-O,O′-bis(2-aminoethyl)-N,N,N′,N′-tetraacetic acid, triethanolamine and triethylenetetramine. The mean value of magnesium in a 40-μl sample of quality control serum was within the appropriate limits of the reference sample. The effects of pH, masking agents and matrix of serum on the fluorescence of CB were investigated.     

Condensation Reaction of Dimethyltin(IV) Oxide with 2‐(2,3‐Dichloroanilino)benzoic Acid Synthesis and Study of a Novel Dimeric Tetraorganodistannoxane

The novel symmetric dimeric tetraorganodistannoxane [(Me₂Sn)₄(DCPA)₂)O₂(OH)₂] ( 2 ) and [(Me₂Sn)₄(DCPA)₂)O₂(OC₂H₅)₂] ( 3 ) where HDCPA is 2‐(2,3‐dichloroanilino)benzoic acid ( 1 ) have been prepared. The crystal structure of 3 has been determined by X‐ray crystallography. Three distannoxane rings are present to the centrosymmetric dimeric tetraorganodistannoxane by virtue of μ₃‐oxo form the central R₄Sn₂O₂ core with a planar Sn₂O₂ ring, resulting in a ladder type structural motif. Five‐coordinated tin atoms are present in the distannoxane dimer. The ligands act as monodentate agents, thus rendering the tin atom five‐coordinated. Significant π → π stacking interactions and intramolecular hydrogen bonds stabilize the structure 3 . The polar imino hydrogen atom participates in intramolecular hydrogen bonds. The formation of the dimeric distannoxanes 2 and 3 represent a ladder‐type carboxylates in which the insertion of a μ₂‐OH or a μ₂‐OC₂H₅ group occurs. This unusual result can be interpreted in terms of a competition between the strength different donors, in which the –OH or the –OC₂H₅ groups show higher donor capacity than the carboxylato group of DCPA.