In:
Chemistry – A European Journal, Wiley, Vol. 11, No. 7 ( 2005-03-18), p. 2111-2124
Kurzfassung:
Reaction of [Ti(NR)Cl 2 (py) 3 ] (R= t Bu or 2,6‐ i Pr 2 C 6 H 3 ) with K 2 [COT] (COT=C 8 H 8 ) or Li 2 [COT′′] (COT′′=1,4‐C 8 H 6 (SiMe 3 ) 2 ) gave the monomeric complexes [Ti(NR)(η 8 ‐COT)] or [Ti(NR)(η 8 ‐COT′′)], respectively. The pseudo‐two coordinate, ′pogo stick′ geometry for these complexes is unique in both early transition‐metal and cyclooctatetraenyl ligand chemistry. In contrast, reaction of [Ti(N‐2,6‐Me 2 C 6 H 3 )Cl 2 (py) 3 ] with K 2 [COT] gave the μ‐imido‐bridged dimer [Ti 2 (μ‐N‐2,6‐Me 2 C 6 H 3 ) 2 (η 8 ‐COT) 2 ]. It appears that as the steric bulk of the imido and C 8 ring substituents are decreased, dimerisation becomes more favourable. Aryl imido COT complexes were also prepared by imido ligand exchange reactions between anilines and [Ti(N t Bu)(η 8 ‐COT)] or [Ti(N t Bu)(η 8 ‐COT′′)]. The complexes [Ti(N t Bu)(η 8 ‐COT)], [Ti(N‐2,6‐ i Pr 2 C 6 H 3 ) 2 (η 8 ‐COT)] and [Ti 2 (μ‐N‐2,6‐Me 2 C 6 H 3 ) 2 (η 8 ‐COT) 2 ] have been crystallographically characterised. The electronic structures of both the monomeric and dimeric complexes have been investigated by using density functional theory (DFT) calculations and gas‐phase photoelectron spectroscopy. The most striking aspect of the bonding is that binding to the imido nitrogen atom is primarily through σ and π interactions, whereas that to the COT or COT′′ ring is almost exclusively through δ symmetry orbitals. A DFT‐based comparison between the bonding in [Ti(N t Bu)(η 8 ‐COT)] and the bonding in the previously reported late transition‐metal ′pogo‐stick′ complexes [Os(N t Bu)(η 6 ‐C 6 Me 6 )], [Ir(N t Bu)(η 5 ‐C 5 Me 5 )] and [Ni(NO)(η 5 ‐C 5 H 5 )] has also been undertaken.
Materialart:
Online-Ressource
ISSN:
0947-6539
,
1521-3765
DOI:
10.1002/chem.200401104
Sprache:
Englisch
Verlag:
Wiley
Publikationsdatum:
2005
ZDB Id:
1478547-X
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