Polyazolyl chelate chemistry. 7.¹ Reactivity of the complexes [MCl(PPh₃)₂{HB(pz)₃}] (M = Ru, Os; pz = pyrazol-1-yl)

The substitution chemistry of the complex [RuCl(PPh₃)₂{HB(pz)₃}] (1) is reported. Treating 1 with the phosphines bis(diphenylphosphino)methane (dppm), 1,2-bis(diphenylphosphino)-ethane (dppe), or 1,1′-bis(diphenylphosphino)ferrocene (dppf) provides the complexes [RuCl-(dppm){HB(pz)₃}] (2), [RuCl(dppe){HB(pz)₃}] (3), or [RuCl(dppf){HB(pz)₃}] (4), respectively. Reactions of 1 with pivaloisonitrile (CNCMe₃) are solvent dependent: In neat dichloromethane or tetrahydrofuran the reaction of 1 with CNCMe₃ provides the neutral complex [Ru(CNCMe₃)Cl(PPh₃)(HB(pz)₃}] (5), while the salt [Ru(CNCMe₃)(PPh₃)₂{HB(pz)₃}]PF ₆ (6· PF₆) is obtained when the reaction is carried out in dichloromethane/methanol mixtures in the presence of NH₄PF₆. The reaction of 4 with CNCMe₃ and NH₄PF₆ provides the salt [Ru-(CNCMe₃)(dppf){HB(pz)₃}]PF ₆(7·PF₆). The bis(isonitrile) salt [Ru(CNCMe₃)₂(PPh₃){HB(pz)₃}]-PF ₆ (8·PF₆) results from the reaction of 1, 5, or 6·PF₆ with excess CNCMe₃ in thf/methanol. The reaction of 1 with Na[S₂CNMe₂] provides the complex [Ru(S₂CNMe₂)(PPh₃){HB(pz)₃}] (9); however similar reaction of 1 or [Ru(NCMe)₂(PPh₃){HB(pz)₃)]PF₆ with Na[O₂CH] failed to cleanly provide [Ru(O₂CH)(PPh₃){HB(pz)₃}] (10), although this could be characterized spectroscopically. Rather, the ultimate product of these reactions was the hydrido complex [RuH(PPh₃)₂{HB(pz)₃)] (11), which could also be obtained in high yield from the reaction of 1 with NaOMe. In a similar manner, reaction of 4 with methanolic NaOMe provided [RuH-(dppf){HB(pz)₃}] (12). The reactions of 1 and 4 with alkynes are solvent dependent: Treating 1 with HC≡CR (R = C₆H₄Me-4, CPh₂OH) in thf provides, respectively, the vinylidene complex [RuCl(=C=CHC₆H₄Me-4)(PPh₃){HB(pz)₃}] (13) and the allenylidene complex [RuCl(=C= C=CPh₂)(PPh₃){HB(pz)₃}] (14), while the reaction of 1 with HC≡CC₆H₄Me-4 in a mixture of thf and methanol provides the alkynyl complex [Ru(C≡CC₆H₄Me-4)(PPh₃) ₂{HB(pz)₃}] (15). The reaction of 1 with HC≡CCPh₂OH in the presence of AgPF₆ provides the allenylidene salt [Ru(=C=C=CPh₂)(PPh₃)₂{HB(pz) ₃}]PF₆ (16·PF₆), and similar treatment of 4 provides [Ru(=C=C=CPh₂)(dppf){HB(pz)₃}]PF₆ (17·PF₆). The reaction of 4 with HC≡CC₆H₄Me-4 and AgPF₆ provides the vinylidene salt [Ru(=C=CHC₆H₄Me-4)(dppf){HB(pz)₃}]PF ₆ (18·PF₆), deprotonation of which (NaOMe) provides [Ru(C≡CC₆H₄Me-4)(dppf){HB(pz)₃}] (19). The allenylidene salt (16·PF₆) with NaOMe provides the γ-alkoxyalkynyl complex [Ru(C≡CCPh₂-OMe)(PPh₃)₂{HB(pz) ₃}] (20). The complex [OsCl(PPh₃)₂{HB(pz)₃}] (21) is obtained from the reaction of [OsCl₂(PPh₃)₃] with K[HB(pz)₃] and is converted by KOH in reluxing 2-methoxyethanol to the hydride complex [OsH(PPh₃)₂{HB(pz)₃}] (22). The vinylidene complex 13 reacts with [Et₂NH₂][S₂CNEt₂] to provide the metallacyclic vinyl complex [Ru{C(=CHC₆H₄-Me-4)SC(NEt₂)S}(PPh ₃){HB(pz)₃}] (23). Similarly the complex 14 and the salt 16·PF₆ react with Na[S₂CNMe₂] to both provide the metallacyclic allenyl complex [Ru{C(=C=CPh₂)SC-(NMe₂)S}(PPh₃){HB(Pz) ₃}] (24). These reactions represent the first examples of the coupling of dithiocarbamates with vinylidene and allenylidene ligands. The complexes 5 and [RuCl-(CS)(PPh₃){HB(Pz)₃}] (25) and the salt (16·PF₆) were characterized crystallographically.