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Reactivity of a Dititanium Bis(pentalene) Complex toward Heteroallenes and Main-Group Element–Element Bonds

DOI: 10.1021/acs.organomet.6b00791 DOI Help

Authors: Alexander F. R. Kilpatrick (University of Sussex) , Jennifer C. Green (University of Oxford) , F. Geoffrey N. Cloke (University of Sussex)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Organometallics

State: Published (Approved)
Published: December 2016
Diamond Proposal Number(s): 11238

Abstract: The reactivity of the Ti═Ti double bond in (μ,η5:η5-Pn†)2Ti2 (1; Pn† = 1,4-{SiiPr3}2C8H4) toward isocyanide and heteroallene substrates, and molecules featuring homonuclear bonds between main-group elements (E–E) has been explored. Reaction of 1 with methyl isocyanide or 1,3-N,N′-di-p-tolylcarbodiimide resulted in the formation of the 1:1 adducts (μ,η5:η5-Pn†)2Ti2(μ,η2-CNMe) (2) and (μ,η5:η5-Pn†)2Ti2(μ-C{N(4-C6H4CH3)}2) (3), respectively, which are thermally stable up to 100 °C in contrast to the analogous adducts formed with CO and CO2. Reaction of 1 with phenyl isocyanate afforded a paramagnetic complex, [(η8-Pn†)Ti]2(μ,κ2:κ2-O2CNPh) (4), in which the “double-sandwich” architecture of 1 has been broken and an unusual phenyl-carbonimidate ligand bridges two formally Ti(III) centers. Reaction of 1 with diphenyl dichalcogenides, Ph2E2 (E = S, Se, Te), led to the series of Ti–Ti single-bonded complexes (μ,η5:η5-Pn†)2[Ti(EPh)]2 (E = S (5), Se (6), Te (7)), which can be considered the result of a 2e– redox reaction or a 1,2-addition across the Ti═Ti bond. Treatment of 1 with azobenzene or phenyl azide afforded [(η8-Pn†)Ti]2(μ-NPh)2 (8), a bridging imido complex in which the pentalene ligands bind in an η8 fashion to each formally Ti(IV) center, as the result of a 4e– redox reaction driven by the oxidative cleavage of the Ti═Ti double bond. The new complexes 2–8 were extensively characterized by various techniques including multinuclear NMR spectroscopy and single-crystal X-ray diffraction, and the experimental work was complemented by density functional theory (DFT) studies.

Subject Areas: Chemistry


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