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Binuclear pentalene titanium carbonyls: Comparison with related cyclopentadienyltitanium carbonyls
Author(s) -
Radu LuanaFlavia,
Attia Amr A. A.,
Lupan Alexandru,
Bruce King R.
Publication year - 2018
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.25762
Subject(s) - pentalene , cyclopentadienyl complex , chemistry , singlet state , titanium , metal carbonyl , dissociation (chemistry) , density functional theory , bond dissociation energy , medicinal chemistry , crystallography , triple bond , photochemistry , stereochemistry , computational chemistry , molecule , double bond , polymer chemistry , organic chemistry , atomic physics , catalysis , physics , metal , excited state
The structures and energetics of the binuclear pentalene titanium carbonyls PnTi 2 (CO) n (Pn = η 5 ,η 5 ‐C 8 H 6 ; n = 8, 7, 6, 5, 4, 3, 2) and their 1,4‐bis(triisopropylsilyl) derivatives related to experimentally studied systems have been examined by density functional theory. Geometric constraints within a η 5 ,η 5 ‐PnTi 2 unit having exclusively pentahapto ring‐titanium bonds limit the TiTi distances to a maximum of ~3.1 Å in the PnTi 2 (CO) n derivatives in contrast to the cyclopentadienyl analogues Cp 2 Ti 2 (CO) n where bonding TiTi distances as long as ~3.9 Å are found. Furthermore, at least one 4‐electron donor η 2 ‐μ‐CO group but never more than 2 such groups are found in the lowest energy PnTi 2 (CO) n structures. The lowest energy PnTi 2 (CO) n structures ( n = 4, 3, 2) by margins of at least 10 kcal/mol have 2 η 2 ‐μ‐CO groups and formal TiTi triple bonds in the singlet spin state. The carbonyl rich species PnTi 2 (CO) n and Pn † Ti 2 (CO) n ( n = 8, 7) are not viable with respect to CO dissociation to give the corresponding hexacarbonyls.