557085-22-0Relevant academic research and scientific papers
Conversion of ethylene to hydride and ethylidyne by an amido rhenium polyhydride
Ozerov, Oleg V.,Huffman, John C.,Watson, Lori A.,Caulton, Kenneth G.
, p. 2539 - 2541 (2003)
Reaction of (PNPCy)ReOCl2 (PNPCy = N(SiMe2-CH2PCy2)2) with Mg and H2 yields (PNPCy)Re(H)4, whose unsaturation is demonstrated by its ability to add H2. (PNPCy)ReH6 is an equilibrium mixture of a structure where all six H's are on Re and a structure where five H's are on Re and one H is on N. (PNPCy)Re(H)4 reacts with C2H4 within 10 min at 25°C to give ethane and (PNPCy)ReH(≡C-CH3), together with its ethylene adduct.
Operationally unsaturated pincer/rhenium complexes form metal carbenes from cycloalkenes and metal carbynes from alkanes
Ozerov, Oleg V.,Watson, Lori A.,Pink, Maren,Caulton, Kenneth G.
, p. 6003 - 6016 (2008/02/02)
Operationally unsaturated (i.e., 16/18-electron) (PNPR)Re(H) 4, where PNPR is N(SiMe2CH2PR 2)2, is reactive at 22°C with cyclic olefins. The first observed products are generally (PNPR)Re(H)2- (cycloalkylidene), with hydrogenated olefin as the product of hydrogen abstraction from the tetrahydride. The tetrahydride complex with R = 1Bu generally fails to react (too bulky), that with R = cyclohexyl suffers a (controllable) tendency to abstraction of 3H from one ring, forming an η3-cyclohexenyl compound, and that with R = iPr generally gives the richest bimolecular reactivity. The cyclic monoolefins studied show distinct reactivity, C6 giving first the carbene and then coordinated cyclohexadiene, C5 giving carbene, then diene, and then η5-C5H5, C8 giving carbene and then η2-cyclooctyne, and C12 giving an η3-allyl. Norbornene gives a π-complex of the norbornene in thermal equilibrium with its carbene isomer; at 90°C, hydrocarbon ligand Cα-Cβ bond cleavage occurs to give, for the first time, a carbyne complex from an internal olefin. Two compounds synthesized here have the formal composition (PNPR)Re + olefin , and each of these is capable of dehydrogenating the methyl group of a variety of alkanes at 110°C to form (PNP)ReH(≡CR).
Transformation of acyclic alkenes to hydrido carbynes by (PNP R)Re complexes
Ozerov, Oleg V.,Watson, Lori A.,Pink, Maren,Caulton, Kenneth G.
, p. 6363 - 6378 (2007/10/03)
Synthesis of (PNPR)ReOCl2 (PNPR = (R 2PCH2SiMe2)2N, R = iPr, Cy, and tBu) from (Me2S)2-ReOCl3 and (PNPR)MgCl is described. Magnesium and H2 convert (PNPR)ReOCl2 first to (PNPR)ReO(H)2 and then to (PNPR)Re(H)4, the last being an operationally unsaturated species which can bind PMe3 or p-toluidine. Acyclic alkenes react with (PNPR)Re(H)4 at 22 °C to give first (PNPR)Re(H)2(olefin) and then (PNP R)ReH(carbyne), in equilibrium with its η2-olefin adduct. Re can also migrate to the terminal carbon of internal olefins to form a carbyne complex. Allylic C-SiMe3 or C-NH2 bonds are not broken, but OEt, OPh, and F vinyl substituents (X) are ultimately cleaved from carbon to give the Re≡C-CH3 complex and liberate HX. DFT calculations, together with detection of intermediates for certain olefins, help to define a mechanism for these conversions.
