Reactions of Alkyne- and Butadiyne-Derived Fluorinated Cyclophosphazenes with Diiron and Dimolybdenum Carbonyls

The reaction of (β-phenylethynyl)­pentafluorocyclotriphosphazene, [(PhCC)­(F)­PN]­(PNF₂)₂, with Fe₂(CO)₉ in refluxing hexane resulted in five new compounds, namely, [Fe­(CO)₂{η²:η²-2,4-(P₃N₃F₅)₂­Ph₂C₄Fe­(CO)₃}-μ-CO] (<b>1</b>), [Fe­(CO)₂{η²:η²-2,5-(P₃N₃F₅)₂­Ph₂C₄Fe­(CO)₃}-μ-CO] (<b>2</b>), [Fe­(CO)₂­{η⁵-2,5-(P₃N₃F₅)₂­Ph₂C₄CO}­C­(Ph)C­(P₃N₃F₅)]­(<b>3</b>), [Fe­(CO)₃­{η²:η²-2,4-(P₃N₃F₅)₂­Ph₂C₄CO] (<b>4</b>), and [Fe­(CO)₃­{η²:η²-2,5-(P₃N₃F₅)₂­Ph₂C₄CO] (<b>5</b>). While compounds <b>1</b>, <b>2</b>, <b>4</b>, and <b>5</b> have five-membered ferracyclopentadiene or cyclopentadienone rings coordinated to the Fe­(CO)₃ unit in the η²:η² mode, compound <b>3</b> has a 2,5-cyclopentadienone ring attached to an Fe­(CO)₂­(P₃N₃F₅)­CC­(Ph) unit, where Fe is η⁵-bonded to the cyclopentadienone ring, and the carbon that is α to the phenyl unit of the Fe­(CO)₂­(P₃N₃F₅)­CC­(Ph) group is σ-bonded to the oxygen atom of the cyclopentadienone ring. Formation of five-membered cyclic compounds having two fluorophosphazene units on the vicinal carbon atoms of C₄R₂R′₂Y rings was not observed in this reaction. No examples of Fe­(CO)₃-bound cyclobutadiene complexes were also isolated from this reaction. A similar reaction in the presence of trimethylamine N-oxide, NMe₃O, was found to proceed at −20 °C with the formation of compounds <b>4</b> and <b>5</b> only. In contrast to the Fe₂(CO)₉ reaction, a reaction of alkyne-derived pentafluorocyclotriphosphazenes, [(RCC)­(F)­PN]­(PNF₂)₂ [R = Ph, Fe­(C₅H₅)₂] with the molybdenum complex Cp­(CO)₃Mo–Mo­(CO)₃Cp (Cp = cyclopentadienyl) in refluxing toluene resulted in the simple tetrahedral clusters Cp­(CO)₂­Mo­(P₃N₃F₅)­C–C­(Ph)­Mo­(CO)₂Cp (<b>6</b>) and Cp­(CO)₂­Mo­(P₃N₃F₅)­C–C­(Fc)­Mo­(CO)₂Cp (<b>7</b>) (Fc = ferrocenyl). A similar reaction of Cp­(CO)₃Mo–Mo­(CO)₃Cp with butadiyne-derived fluorophosphazenes, [(RCC–CC)­(F)­PN]­(PNF₂)₂ [R = Ph, Fe­(C₅H₅)₂], yielded the tetrahedral clusters Cp­(CO)₂­Mo­(P₃N₃F₅)­C–C­(CCPh)­Mo­(CO)₂Cp (<b>8</b>) and Cp­(CO)₂Mo­(P₃N₃F₅)­C–C­(CCFc)­Mo­(CO)₂Cp (<b>9</b>) with the tetrahedral Mo₂C₂ unit forming exclusively with the alkyne unit of the butadiyne group bound to the cyclophosphazene ring. The crystal structures and infrared spectral data of these molybdenum clusters showed the presence of a semibridging carbonyl on one of the molybdenum units. All new compounds were characterized by IR, NMR [¹H, ¹³C­{¹H}, ³¹P­{¹H}, and ¹⁹F­{¹H}] and high-resolution mass spectrometry studies. Compounds <b>2</b>, <b>3</b>,<b> 5</b>, and <b>7–9</b> were also structurally characterized using single-crystal X-ray diffraction studies