Abstract
A series of tris(oxoimidazolyl)hydroborato ligands, which serve as L
X [O
] donors, have been employed to obtain organometallic zirconium compounds in an uncommon oxygen-rich coordination environment. For example, Cp[To
]ZrCl
has been synthesized via the reaction of [To
]Na with CpZrCl
and bears a structural resemblance to the bent metallocene dichloride derivative Cp
ZrCl
. In addition, the half-sandwich counterparts [To
]ZrCl
and [To
]ZrCl
have been obtained by metathesis of ZrCl
with [To
]Na and [To
]Na, respectively. The structurally related zirconium benzyl compounds [To
]Zr(CH
Ph)
(R = Me, Bu
, 1-Ad) have also been synthesized via the reactions of [To
]Tl with Zr(CH
Ph)
, and X-ray diffraction studies demonstrate that the benzyl ligands in these compounds are conformationally flexible and exhibit a large range of Zr-CH
-Ph bond angles (94.7-131.7°). Protolytic cleavage of one of the benzyl ligands of [To
]Zr(CH
Ph)
(R = Bu
, 1-Ad) may be achieved by treatment with [PhNHMe
][B(C
F
)
] to generate {[To
]Zr(CH
Ph)
}[B(C
F
)
], which are catalysts for the polymerization of ethylene. The molecular structure of the ether adduct, {[To
]Zr(CH
Ph)
(OEt
)}[B(C
F
)
], has been determined by X-ray diffraction. In addition to the use of tris(oxoimidazolyl)hydroborato ligands, bis(oxoimidazolyl)hydroborato ligands have also been used to obtain zirconium benzyl compounds in oxygen-rich environments, namely, [Bo
]
Zr(CH
Ph)
and [Bo
]
Zr(CH
Ph)
.