Facile Cleavage of Organochalcogen Hybrid (NEEN, NEN, EN, where E = Se or Te) Ligand C−E and E−E Bonds by Pd(II)

The synthesis and characterization of chiral hybrid ligand R 2 *Se 2 (R* = 2-Me 2 NCH(Me)C 6 H 4 ) ( 9 ) and some of its derivatives is described. The reaction of 9 with a Pd(II) chloride complex leads to cleavage of the Se−Se bond and formation of the corresponding areneselenenyl chloride, R*SeCl ( 18 ). However, reactions of [ RS; RS ] and [ SR; SR ] bis[2-{1-(dimethylamine)ethyl}ferrocenyl] diselenides ( 7 and 8 ) with a Pd(II) chloride complex under identical conditions afford dinuclear complexes [PdCl{(SeC 5 H 3 CH(Me)NMe 2 -2)Fe(C 5 H 5 )}] 2 ( 19 and 20 ). Reaction of achiral ditelluride, R 2 Te 2 (R = 2-Me 2 NCH 2 C 6 H 4 ) ( 10 ), with a Pd(II) chloride complex gives a novel dinuclear complex, [PdCl(TeC 6 H 4 CH 2 NMe 2 -2)] 2 ( 21 ), and the dimeric tellurium complex (RTeCl) 2 ( 22 ), whereas the reaction of chiral Schiff base tridentate tellurium ligand R′ 2 Te (R′ = 2-C 6 H 4 CH═NCH(Me)C 6 H 5 ) ( 11 ) with a Pd(II) chloride complex produces cleaved products (R′PdCl) 2 ( 23 ) and (R′TeCl) 2 ( 24 ). Similarly, the reaction between the tridentate ligand R 2 Te ( 12 ) and Pd(COD)Cl 2 gives 22 and the dimeric palladium complex (RPdCl) 2 ( 25 ). The treatment of bidentate ligand RTeMe ( 13 ) results in decomposition of the ligand and precipitation of Te. All the compounds are characterized by detailed IR and NMR ( 1 H, 13 C, 77 Se, and 125 Te) spectroscopic techniques, MS, and optical rotation measurements. The structures of R*SeBr ( 17 ), 21, 24, and 25 were determined by single-crystal X-ray crystallography. In 17 the coordination geometry around selenium is essentially T-shaped with a short Se···N distance (2.132(6) Å). The palladium tellurolato complex 21 crystallizes as a centrosymmetric dimer. Compound 23 crystallizes as a dimer in which each tellurium atom coordinates to two bridging chlorines, one nitrogen, and one carbon. Compound 25 crystallizes as a chloro-bridged centrosymmetric dimer.