Syntheses and structures of the chalcocarbonyl complexes OsCl 2(CO)(CE)(PPh 3) 2 (E = S, Se, Te)

Abstract

The Group VI nucleophiles HE − (E = O, S, Se, Te) react with the electrophilic dichlorocarbene ligand in the complex OsCl 2(CCl 2)(CO)(PPh 3) 2 to form the corresponding chalcocarbonyl derivatives OsCl 2(CO)(CE)(PPh 3) 2. OsCl 2(CO)-(CTe)(PPh 3) 2 is the first reported tellurocarbonyl complex, and the compounds OsCl 2(CO)(CE)(PPh 3) 2 constitute the first complete series of chalcocarbonyl complexes. H 2O, H 2S and H 2Se also react with the dichlorocarbene complex to yield the corresponding chalcocarbonyl derivatives OsCl 2(CO)(CE)(PPh 3) 2, although OsCl 2(CO)(CTe)(PPh 3) 2 cannot be formed this way. The thiocarbonyl, dichlorocarbene complex OsCl 2(CCl 2)(CS)(PPh 3) 2 gives tractable products with H 2O, H 2S and H 2Se, and in this way the mixed chalcocarbonyl compounds OsCl 2(CS)(CE)(PPh 3) 2 can be isolated. X-ray crystal structure determinations have been carried out on the complexes OsCl 2(CO)(CS)(PPh 3) 2, OsCl 2(CO)(CSe)(PPh 3) 2 and OsCl 2(CO)(CTe)(PPh 3) 2. The CS and CSe complexes are isostructural and crystallise in space group P 1 , with two molecules in unit cells of dimensions: CS a 12.837(1), b 14.302(1), c 10.452(1) Å, α 92.45(1), β 97.42(1), γ 99.86(1)°; CSe a 12.846(3), b 14.341(3), c 10.462(4) Å, α 92.26(2), β 97.67(2), γ 99.76(1)°. The CTe complex crystallises in space group P2 1/ n, with four molecules in a cell of dimensions a 14.211(3), b 18.084(4), c 14.857(3) Å, β 113.29(2)°. The coordinated CTe ligand in OsCl 2(CO)(CTe)(PPh 3) 2 displays similar overall structural features to the other coordinated chalcocarbonyl ligands in that the OsCTe angle is ca. 180° and the OsCTe and CTe bonds are very short. For each of the complexes the OsCE bond length is shorter than the OsCO bond length in the same molecule, although only for the thiocarbonyl complex is the difference significant. The trans-influence of the chalcocarbonyl ligands increases in the order CO < CS ≤ CSe < CTe.