New diorganoselenium(II) compounds and their behavior toward late transition metals

Abstract Hypervalent diorganoselenium(II) compounds of type 1-{2-[(2-(3,5-dimethyl-4,5-dihydro-1H-pyrazol-1-yl)ethyl)selanyl]phenyl}-N,N-dialkylmethanamine, [2-(R 2 NCH 2 )C 6 H 4 ][(3,5-dmpz)CH 2 CH 2 ]Se, [R = Me ( 1 ), Et ( 2 ), dmpz = dimethylpyrazole] were obtained by reacting 1-(2-bromoethyl)-3,5-dimethyl-1H-pyrazole [(3,5-dmpz)CH 2 CH 2 Br] with alkali metal aryl selenolates of type [2-(R 2 NCH 2 )C 6 H 4 ]SeM (R = Me, M = Na; R = Et, M = Li) in a 1:1 molar ratio. The coordination ability of species 1 , as well as that of bis[2-(3,5-dimethyl-1H-pyrazol-1-yl)ethyl]selane, [(3,5-dmpz)CH 2 CH 2 ] 2 Se ( 3 ) toward several late transition metals (Pd, Au, Ag) was investigated by reacting the neutral ligands 1 and 3 with PdCl 2 , AuCl(tht) and AgOTf in a 1:1 molar ratio. The neutral ligands 1 – 3 , as well as the gold(I), silver(I) and palladium(II) adducts [2-(Me 2 NCH 2 )C 6 H 4 ][(3,5-dmpz)CH 2 CH 2 )]SeAuCl ( 4 ), [(3,5-dmpz)CH 2 CH 2 )] 2 SeAuCl ( 5 ), [2-(Me 2 NCH 2 )C 6 H 4 ][(3,5-dmpz)CH 2 CH 2 )]SeAgOTf ( 6 ), [(3,5-dmpz)CH 2 CH 2 )] 2 SeAgOTf ( 7 ) and [(3,5-dmpz)CH 2 CH 2 )] 2 SePdCl 2 ( 8 ) were characterized by NMR spectroscopy ( 1 H, 13 C, 77 Se) and mass spectrometry. The reaction between 1 and PdCl 2 in a 1:1 molar ratio resulted in the formation of a complex reaction mixture of which the species [2-(Me 2 NCH 2 )C 6 H 4 SePdCl] 2 ( 9 ) and 1-(2-chloroethyl)-3,5-dimethyl-1H-pyrazole [(3,5-dmpz)CH 2 CH 2 Cl] were unambiguously identified. Single crystal X-ray diffraction studies revealed a monomeric structure with a distorted T-shaped coordination geometry of type ( C , N )Se C for the neutral ligand 1 and supramolecular associations based on dimeric units in case of species 9 and 9 ·0.5CH 2 Cl 2 ·0.5THF.