| Abstract
| - Operationally unsaturated (i.e., 16/18-electron) (PNPR)Re(H)4, where PNPR is N(SiMe2CH2PR2)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 = tBu generally fails to react (too bulky), that with R = cyclohexyl suffersa (controllable) tendency to abstraction of 3H from one ring, forming an η3-cyclohexenyl compound, andthat with R = iPr generally gives the richest bimolecular reactivity. The cyclic monoolefins studied showdistinct 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 aninternal olefin. Two compounds synthesized here have the formal composition “(PNPR)Re + olefin”, andeach of these is capable of dehydrogenating the methyl group of a variety of alkanes at 110 °C to form(PNP)ReH(⋮CR).
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