%0 Journal Article
%A Natoli, Sean N.
%A Azbell, Tyler J.
%A Fanwick, Phillip E.
%A Zeller, Matthias
%A Ren, Tong
%D 2016
%T A Synthetic Approach to Cross-Conjugated Organometallic
Complexes Based on geminal-Diethynylethene and CoIII(cyclam)
%U https://acs.figshare.com/articles/journal_contribution/A_Synthetic_Approach_to_Cross-Conjugated_Organometallic_Complexes_Based_on_i_geminal_i_-Diethynylethene_and_Co_sup_III_sup_cyclam_/4010124
%R 10.1021/acs.organomet.6b00657.s001
%2 https://acs.figshare.com/ndownloader/files/6453231
%K Co III
%K analysis
%K acyclic cross-conjugated complexes
%K DEE
%K orbital
%K ligand
%K PF
%K DFT
%K OTf
%K Cross-Conjugated Organometallic Complexes
%K gem
%K σ-
%K Cl
%K cyclam
%K geminal
%X A series
of CoIII(cyclam) complexes ([1a,b]Cl, [2a–c]PF6, [3]Cl2, [4a](OTf)4, [4b](PF6)2, and [5]Cl2) (cyclam = 1,4,8,11-tetraazacycloctetradecane)
bearing a geminal-diethynylethene ligand (gem-DEE) is reported. Syntheses of these acyclic cross-conjugated
complexes were accomplished in satisfactory yields, and structural
characterizations established that the geometrical feature of gem-DEE is largely preserved upon metalation. Combined structural
and electrochemical studies suggest that the gem-DEE
ligand, as a σ-donor, is weaker than phenylethynyl but stronger
than butadiynyl in CoIII(cyclam) complexes. Voltammetric
analysis indicated a weak but discernible Co–Co coupling across
the gem-DEE bridge in [3]Cl2 and [4a](OTf)4, while the addition of a
second acetylide in the trans position diminished
such coupling in [4b](PF6)2. DFT
analysis revealed significant dπ–π mixing around
the cobalt centers with extended π-overlap in the highest occupied
orbitals and substantial σ-based mixing in the lowest unoccupied
orbitals of [3]Cl2 and [4a](OTf)4, the latter of which likely contributes to the weak Co–Co
coupling.
%I ACS Publications