Competitive CH activation in (pentamethylcyclopentadienyl)(cyclooctatetraene)alkylzirconium or cyclooctatrienyne ligands. Molecular structure of Cp[sup *]Zr([mu]-[eta][sup 8]:[eta][sup 2]-C[sub 8]H[sub 6])ZrCp[sup *]([eta][sup 4]C[sub 8]H[sub 8]), a dinuclear zwitterionic zirconium complex with a bridging cyclooctatrienyne ligand

Journal Article · Fri Jan 01 00:00:00 EST 1993 · Organometallics; (United States)

DOI:https://doi.org/10.1021/om00025a032· OSTI ID:6567417

Sinnema, P J; Meetsma, A; Teuben, J H ^[1]

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1. Univ. of Groningen (Netherlands)

Thermolysis of Cp[sup *]Zr(COT)R(Cp[sup *] = [eta][sup 5]-C[sub 5]Me[sub 5], COT = [eta][sup 8]-C[sub 8]H[sub 8], R = CH[sub 2]SiMe[sub 3],Me) proceeds via a double hydrogen abstraction from a cyclooctatetraene ligand to give RH and Cp[sup *]Zr([mu]-[eta][sup 8]:[eta][sup 2]-C[sub 8]H[sub 6])ZrCp[sup *]([eta][sup 4]-C[sub 8]H[sub 8]) as the kinetic product. Cp[sup *]Zr([mu]-[eta][sup *]:[eta][sup 2]-C[sub 8]H[sub 6])ZrCp[sup *]([eta][sup 4]-C[sub 8]H[sub 8]) undergoes a thermally induced hydrogen transfer from the pentamethylcyclopentadienyl ligands to the cyclooctatetraenediyl ligand to give the thermodynamic product FvZrCOT (Fv = [eta][sup 6]-C[sub 5]Me[sub 4]CH[sub 2]). For Cp[sup *]Zr(COT)R (R = CH[sub 2]Ph) a different thermolysis reaction was observed, in which FvZrCOT was the major product at low temperatures, together with some Cp[sup *]Zr([mu]-[eta][sup 8]:[eta][sup 2]-C[sub 8]H[sub 6])-ZrCp[sup *]([eta][sup 4]-C[sub 8]H[sub 8]). The latter does not convert into the thermodynamic product at the temperature of thermolysis, indicating an alternative, direct, thermal decomposition pathway to FvZrCOT for R = CH[sub 2]Ph, with preferred hydrogen abstraction from the sp[sup 3] carbon of the pentamethylcyclopentadienyl ligand. Cp[sup *]Zr([mu]-[eta][sup 8]:[eta][sup 2]-C[sub 8]H[sub 6])ZrCp[sup *]([eta][sup 4]-C[sub 8]H[sub 8]) crystallizes in the monoclinic space group P2[sub 1]/n. The molecular structure shows an unprecedented cyclooctatrienyne ligand, bridged asymmetrically between the Zr atoms. The formulation as a cyclooctatrienyne complex is formal; the actual bonding of the ligand is as a dimetalated [eta][sup 8]-cyclooctatetraene-1,2-diyl. 40 refs., 1 fig., 3 tabs.

• OSTI ID: 6567417
• Journal Information: Organometallics; (United States), Vol. 12:1; ISSN 0276-7333
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ORGANOMETALLIC COMPOUNDS
PYROLYSIS
ZIRCONIUM COMPLEXES
CYCLOALKENES
CYCLOALKYNES
DIAMAGNETISM
HYDROGEN
HYDROGEN TRANSFER
LIGANDS
MOLECULAR STRUCTURE
MONOCLINIC LATTICES
ALKENES
ALKYNES
CHEMICAL REACTIONS
COMPLEXES
CRYSTAL LATTICES
CRYSTAL STRUCTURE
DECOMPOSITION
ELEMENTS
HYDROCARBONS
MAGNETISM
NONMETALS
ORGANIC COMPOUNDS
THERMOCHEMICAL PROCESSES
TRANSITION ELEMENT COMPLEXES
400201* - Chemical & Physicochemical Properties