Preparation of [(η⁵-MeC₅H₄)Mn(CO)(NO)(DMPP)]PF₆, DMPP = 1-Phenyl-3,4-Dimethylphosphole, and its Intramolecular [4+2] Diels-Alder Cycloaddition Reaction with Ph₂PCH=CH₂

Abstract

(η⁵-MeC₅H₄)Mn(CO)₃ reacts with NaNO₂, HCI and KPF₆ to form [(η⁵-MeC₅H₄)Mn(NO)(CO)₂]PF₆(1). Compound (1) reacts with 1-phenyl-3,4-dimethylphosphole (DMPP) to form [(η⁵-MeC₅H₄)Mn(NO)(CO)(DMPP)]PF₆(2). Compound (2) reacts with Ph₂PCH=CH₂ (DPVP) to form [(η⁵-MeC₅H₄)Mn(NO) (DMPP)(DPVP)]PF₆(3), which undergoes an intramolecular [4+2] Diels-Alder cycloaddition reaction at 50°C to form [(η⁵-MeC₅H₄)Mn(NO)(2-diphenyl-phosphino)-5,6-dimethyl-7-phenyl-7-phosphabicyclo[2. 2. 1]hept-5-ene)]PF₆(4a,b). The new complexes were characterized by elemental analyses, physical properties, infrared spectroscopy, and ¹H, ¹³C{¹H}and “P(¹H) NMR spectroscopy. The structures of (2) and (4a) were confirmed by X-ray crystallography. They crystallize in the Pna2₁ and P2_1/n space groups, respectively, in unit cells of the following dimensions: (2): a = 19. 333(3)Å, b = 11. 011(1)Å, c = 10. 562(2)Å, α = β = γ = 90°, p(calc) = 1. 552 g er⁻³, Z = 4. (4a): a = 10. 932(2)Å, b = 19. 220(2)Å, c = 16. 957(2)Å, β = 104. 62(1)°, p(calc) = 1. 367 g cm⁻³, Z = 4. Refinements converged to R(F) = 0. 0562 and 0. 0752 for 2358 and 4504 independent observed (I ≥ 20° (I)) reflections, respectively.