| Popis: |
A large-scale, high-yield synthesis of the aminocarbyne complexes Tp′(CO)2WCN(R)Et (5: R Me; 6: R Et) [Tp′ = hydridotris(3,5-dimethylpyrazol-1-yl)borate] is reported, starting from Tp′W(CO)3I (2). The first step of the synthetic procedure involves thermal decarbonylation of 2 with EtNC to give cis-Tp′W(CO)2(CNEt)I (3). Complex 3 is then reduced with Na/Hg to give the metallate Na[Tp′W(CO)2(CNEt)] (4). Finally, complex 4 is alkylated with RI (R Me, Et) exclusively at the isocyanide nitrogen to give the aminocarbyne complexes 5 and 6. In contrast, the metallates Na[(η5-C5R′5)W(CO)2(CNEt)] (R′ H, Me) undergo alkylation with RI at the metal centre to afford the WII alkyl complexes cis/trans-(η-C5R′5)W(CO)2(CNEt)R. This difference in reactivity is ascribed to the steric demands of the Tp′ ligand, which shields the metal centre from the incoming electrophile. |
