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

Abstract

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 CHd 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.

Palladium selenolates via oxidative addition of organylselenenyl halides to palladium(0) precursor and via cleavage reaction of diselenides: Synthesis, structure and spectroscopic investigation

“…For instance, diselenide (Me 2 NCH 2 CH 2 Se) 2 [31]. Very recently, Singh and co-workers have reported the cleavage reactions of a series of a related chiral and achiral multidentate selenium and tellurium ligands (1aec: Chart 1) with palladium(II) precursor [32]. Diselenide 1b provided a selenolate bridged dinuclear complex 2a on reaction with Pd(COD)Cl 2 .…”

Bis{μ-2-[(dimethylamino)methyl]benzeneselenolato}bis[chloridopalladium(II)] dichloromethane hemisolvate

“…In addition to this, organotellurium compounds have been used in catalytic carbon-carbon formation. Bridged dimers of palladium mediated by Se (Nakata et al, 2009;Chakraborty et al, 2011;Oilunkaniemi et al, 1999;Oilunkaniemi et al, 2001;Brown & Corrigan, 2004;Dey et al, 2006) or Te (Oilunkaniemi et al, 2000;Kaur et al, 2009;Dey et al, 2006) have been previously reported. Such dimers involving two square planar coordination spheres can adopt either a coplanar or hinged arrangement.…”

“…For structures of dimeric Se-bridged Pd derivatives, see: Nakata et al (2009);Chakraborty et al (2011); Oilunkaniemi et al (1999Oilunkaniemi et al ( , 2001; Brown & Corrigan (2004); Dey et al (2006) and for structures of dimeric Te-bridged Pd derivatives, see: Oilunkaniemi et al (2000); Kaur et al (2009);Dey et al (2006). For the use of the SQUEEZE routine in PLATON, see: Spek (2009 Symmetry codes: (i) x þ 1 2 ; Ày þ 1 2 ; Àz þ 2; (ii) Àx þ 1 2 ; y À 1 2 ; Àz þ 1.…”

“…In the case of a hinged cis arrangemnt the possibility of chirality exisits. While the majority of previously determined Se/Te bridged Pd dimeric structures are both coplanar and trans, there have been a small number which exhibit either a hinged or cis arrangment of ligands about the bridging plane (Kaur et al, 2009;Oilunkaniemi et al, 2000). However, in no previous case has this resulted in a chiral structure.…”

Chemistry of selenium/tellurium-containing Schiff base macrocycles

“…The other two nitrogen atoms [17]. It is of interest to note that, unlike the macrocyclic Schiff bases, the reaction of Pd(II) with tellurium containing chiral acyclic Schiff base ligand leads to the cleavage of C-Te bond [39].…”