A NEW FAMILY OF (ARENE)OSMIUM(0) AND (ARENE)OSMIUM(II) COMPLEXES

The arene carbonyl complex [(mes)OsCl2(CO)] (3), which is obtained from [(mes)OsCl2]„ (1) and CO in CH2C12, 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(O) 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), [(CeH^OsHjiCO)] (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 teri-butyl alcohol as a proton source. Reaction of 10 with HBF4 in CH2C12 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(O) complexes [(mes)Os(C2H4)2] (18) and [(mes)Os(C7H8)] (19) have been prepared from 1 and ethylene or norbornadiene, respectively, in presence of Na2C03 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. © 1990, American Chemical Society. All rights reserved.