Synthesis and Structural Characterization of {[Me₂Si(C₅Me₄)₂]Zr(η²-C₂H₄)H}₂Mg:  An ansa-Zirconocene Ethylene−Hydride Complex

Formation and reactivity of the zirconium ethylene complexes [η5-C5H3-1,3-(SiMe2CH2PR2)2]Zr(η2-CH2=CH2)(X) (R = Me, Pr i; X = Br, C5H5)

“…However, the phosphines are bound considerably closer to the metal in 2b, with Zr-P bond distances averaging 2.72 Å in comparison to 2.86 Å for 2c. The C-C bond distance of the ethylene ligand is similar in these complexes to that found for other monomeric Zr(II) ethylene complexes (14,16,21). The lengthening of this bond compared to 1.337 Å found in free ethylene (22) is indicative of significant back-bonding from the metal as represented in the Dewar-Chatt-Duncanson model (23,24) and supports a Zr(IV) metallacyclopropane bonding depiction (A).…”

“…Although zirconium-alkene complexes are proposed as intermediates in several important synthetic transformations, (12,13) the number of characterizable species has been restricted to a few metallocene-type systems, (14)(15)(16)(17) the majority of which are isolated by the use of a trapping donor (typically a phosphine) to stabilize these complexes. The ethylene derivatives introduced in this report expand this sample to include 16-electron mono(cyclopentadienyl) complexes and a related 18-electron metallocene analogue; in addition, some substitution studies are included.…”

Synthesis, Structure and Theoretical Studies of the Hydrido Inverse Crown [K2Mg2(NiPr2)4(μ‐H)2·(toluene)2]: a Rare Example of a Molecular Magnesium Hydride with a Mg‐(μ‐H)2‐Mg Double Bridge

“…The MgϪH bond length in 1 is the same within experimental error as that in 2. These dimensions resemble those of the MgϪH bonds present in a selection of other heterobimetallic hydride complexes: [{(C 5 Me 5 ) 2 Ti(µ-H) 2 } 2 Mg], [18] (mean, 1.88 Å ); [{(C 5 HMe 4 ) 2 Ti(µ-H) 2 Mg(THF)(µ-Cl)} 2 ], [19] (mean, 1.91 Å ); and [({Me 2 Si(C 5 Me 4 ) 2 }Zr{η 2 -C 2 H 4 }H) 2 Mg], [20] (mean, 1.82 Å ). The magnesium atoms in 1 are forced into a highly The closest K···H contact in 1 is 2.96 (3) [17] [mean, 2.63 Å ; range, 2.44 (6) …”

Hydrozirconation

“…Note that the synthesis and reactivity of anionic [77,78] and cationic [79] hydrido zirconocene(IV) complexes have been investigated but will not be addressed in this chapter.…”