1235974-19-2Relevant academic research and scientific papers
Reactions of the phosphinidene-bridged complexes [Fe2(η 5-C5H5)2(μ-PR)(μ-CO)(CO) 2] (R = Cy, Ph, 2,4,6-C6H2 tBu 3) with diazoalkanes. Formation and rearrangements of phosphadiazadiene-bridged derivatives
Alvarez, M. Angeles,Garcia, M. Esther,Gonzalez, Rocio,Ruiz, Miguel A.
, p. 5140 - 5153 (2010/12/24)
The phosphinidene complexes [Fe2Cp2(μ-PR)(μ-CO) (CO)2] (Cp = η5-C5H5; R = Cy, Ph, Mes*; Mes* = 2,4,6-C6H2tBu 3) react readily with diazoalkanes N2CR′R″ (R′ = H, R″ = H, CO2Et, SiMe3; R′ = R″ = Ph) in dichloromethane solution at room temperature or below to give the corresponding P:P-bridged phosphadiazadiene derivatives [Fe 2Cp2(μ-RPN2CR′R″)(μ-CO)(CO) 2] (2) with high yield. The diazomethane derivative (Fe-Fe = 2.6198(6) A) is protonated selectively with HBF4· OEt2 at the P-bound nitrogen atom to yield the aminophosphide derivative [Fe2Cp2(μ-CyPNHNCH2)(μ-CO)(CO) 2](BF4) (Fe-Fe = 2.6126(5) A). Compounds 2 decompose upon heating in toluene solution at 363 K to give the dimer [Fe 2Cp2(CO)4] as the only organometallic product. The same result was obtained when irradiating with visible-UV light toluene solutions of the phenylphosphinidene-derived compounds. In contrast, relatively selective decarbonylations could be induced photochemically when R = Cy, Mes*. The reaction products, however, were strongly dependent on the nature of all substituents present in compounds 2. The diazomethane derivative yielded a mixture of the P:N-bound phosphadiazadiene complex [Fe 2Cp2(μ-CyPN2CH2)(μ-CO) 2] (major) and the phosphaalkene derivative [Fe2Cp 2(μ-CyPCH2)(μ-CO)(CO)] (minor). In contrast, the ethyldiazoacetate derivative gave the paramagnetic complex [Fe 2Cp2{μ-CyPN2CH(CO2Et)}(μ-CO) (CO)], possibly containing a μ-P:P,C-phosphadiazadiene ligand, which upon chromatography fully rearranges into the aminophosphide-iminoacyl complex [Fe2Cp2{μ-CyPNHNC(CO2Et)}(μ-CO)(CO)] (Fe-Fe = 2.6261(8) A), possibly through a protonation/deprotonation sequence on the alumina surface. The trimethylsilyldiazomethane derivative instead gave directly the analogous aminophosphide-iminoacyl complex [Fe 2Cp2{μ-CyPN(SiMe3)NCH}(μ-CO)(CO)], now resulting from an unusual 1,3-shift of the SiMe3 group along the ligand backbone. Finally the photochemical treatment of the ethyldiazoacetate derivative of the supermesithylphosphinidene substrate gave the complex [Fe 2Cp2{μ-Mes*PN2CH(CO 2Et)}(μ-CO)2] (Fe-Fe = 2.514(1) A), containing a P:N-bridged phosphadiazadiene ligand bound to the dimetal center in a novel coordination mode, this involving the P-bound nitrogen atom, instead of the C-bound nitrogen.
