A new family of (arene)osmium(0) and -osmium(II) complexes

Article abstract of DOI:10.1021/om00156a029

The arene carbonyl complex [(mes)OsCl₂(CO)] (3), which is obtained from [(mes)OsCl₂]_n (1) and CO in CH₂Cl₂, reacts with CH₃MgI and CH₃Li to give the monomethyl- and dimethylosmium(II) compounds [(mes)OsCH₃(CO)I] (4) and [(mes)Os(CH₃)₂(CO)] (5) in good yields. Treatment of 5 with [CPh₃]PF₆ leads to the formation of [(mes)OsH(C₂H₄)(CO)]PF₆ (6), which by deprotonation with NaH gives the osmium(0) complex [(mes)Os(C₂H₄)(CO)] (7). With [(mes)Os(CD₃)₂(CO)] (5-d₆) as starting material, the deuterated compound [(mes)Os(C₂D₄)(CO)] (7-d₄) has similarly been prepared, which proves that neither the solvent nor the particular reagent is involved in the two reaction steps. The synthesis of the dihydrido complexes [(mes)OsH₂(CO)] (10), [(C₆H₆)OsH₂(CO)] (13), and [(C₆Me₆)RuH₂(CO)] (14) has been achieved by treatment of the corresponding dichloro or diiodo derivatives with sodium in liquid ammonia in presence of tert-butyl alcohol as a proton source. Reaction of 10 with HBF₄ in CH₂Cl₂ produces the BF₄ salt of the [(mes)-OsH₃(CO)]+ cation (15), which reacts with CO to give [(mes)OsH(CO)₂]BF₄ (16). Deprotonation of 16 with NaH or NaNH₂ in THF leads to the formation of the dicarbonyl compound [(mes)Os(CO)₂] (17). The related olefin osmium(0) complexes [(mes)Os(C₂H₄)₂] (18) and [(mes)Os(C₇H₈)] (19) have been prepared from 1 and ethylene or norbornadiene, respectively, in presence of Na₂CO₃ and ethanol. By use of 3 and 4 as starting materials, the monocarbonylosmium(II) compounds [(mes)OsH(CO)Cl] (9) and [(mes)-OsCH₃(CO)H] (8) have also been synthesized.