Cheon Lab

The organometallic compounds bis(allyl)zinc and bis(2-methylallyl)zinc have been shown to serve as MOCVD precursors for the deposition of zinc at temperatures as low as 150 °C. The deposits on Si(100) wafers, quartz, copper, and aluminum consist of aggregates of hexagonal plates and columns. On silicon(100) substrates and at low background pressures (10−4 Torr), the zinc crystals are oriented preferentially with their c axes perpendicular to the silicon surface. The organic byproducts generated under CVD conditions are 1,5- hexadiene (76 mol %), 2-methyl-1,4-pentadiene (14 mol %), and propene (10 mol %); except for the pentadiene product, analogous hydrocarbons in similar amounts are formed when bis(2-methylallyl)zinc is used as the precursor. In situ spectroscopic studies on single-crystal Cud (111) substrates show that bis(allyl)zinc transfers its allyl groups to the surface below 250 °C; the surface-bound allyl groups are probably bound in a trihapto fashion. On clean surfaces, the

Synthesis of dichloro cobalt (Ⅲ) complexes of a flexible N2O2-type tetradentate ligand, ethylenediamene-N, N'-di- -isobutyric acid (eddib), has yielded two geometrical isomers, s-cis-(Co (eddib) Cl2)-and uns-cis-(Co (eddib) Cl2)-. A series of substitution reactions, (Co (eddib) Cl2)- →(CO (eddib) Cl H2O)→(Co (eddib) CO_3)-→(Co (eddib (H2O)2)+ have been run for each of the two geometrical isomers. The reaction between the s-cis-(Co (eddib) Cl2)- complex and L-alanine (L-als) or S-methyl-L-cysteine (L-mcy) gave the meridional s-cis-[Co (eddib)(aa))(aa= L-ala or L-mcy) complex. The S-methyl-L-cysteine was found to coordinate to cobalt (Ⅲ) ion via the nitrogen and oxygen donor atoms.

A new optically active ONNO-type tetradentate ligand, ethylenediamine-N,N′- di-S-isobutylacetate (SS-eniba), has been synthesized. During the preparation of diaqua cobalt(III) complexes of SS-eniba, [Co(SS-eniba)(H2O)2]+, the title ligand has coordinated stereospecifically to the cobalt(III) ion to give three isomers, Δ-s-cis, Δ-uns-cis and Λ-uns-cis, which have been isolated and characterized via electronic absorption, circular dichroism (CD), and 1H NMR spectroscopy, along with elemental analysis data. The preparation of Δ-s-cis-[Co(SS-eniba)Cl2]+ and Δ-s-cis-[Co(SS-eniba)CO3]+ are also reported.