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Binuclear Cyclopentadienylmanganese Carbonyl Thiocarbonyls: Four‐Electron Donor Bridging Thiocarbonyl Groups of Two Types and a Bridging Acetylenedithiolate Ligand
Author(s) -
Zhang Zhong,
Li Qianshu,
Xie Yaoming,
King R. Bruce,
Schaefer Henry F.
Publication year - 2010
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201000172
Subject(s) - chemistry , disproportionation , crystallography , singlet state , dissociation (chemistry) , density functional theory , ligand (biochemistry) , bridging ligand , stereochemistry , crystal structure , computational chemistry , catalysis , biochemistry , physics , receptor , nuclear physics , excited state
Abstract As a starting point, the mononuclear cyclopentadienylmanganese carbonyl thiocarbonyls [CpMn(CS)(CO) n ] (Cp = η 5 ‐C 5 H 5 ; n = 2, 1, 0) and binuclear derivatives [Cp 2 Mn 2 (CS) 2 (CO) n ] ( n = 3, 2, 1, 0) have been studied by density functional theory (DFT). For coordinately saturated binuclear [Cp 2 Mn 2 (CS) 2 (CO) 3 ], the four electron donor end‐on CE(E = O, S) bridged structures are preferred energetically over the normal CE (E = O, S) bridged structures, analogous to [Cr 2 (CS) 2 (CO) 9 ]. The lowest energy structure for [Cp 2 Mn 2 (CS) 2 (CO) 2 ] has one four‐electron donor bridging η 2 ‐μ‐CS group. However, this structure is thermodynamically unstable with respect to disproportionation into [Cp 2 Mn 2 (CS) 2 (CO) 3 ] and [Cp 2 Mn 2 (CS) 2 (CO)]. Only two structures are found for [Cp 2 Mn 2 (CS) 2 (CO)] as is the case for the carbonyl analogue [Cp 2 Mn 2 (CO) 3 ]. The global minimum of [Cp 2 Mn 2 (CS) 2 (CO)], a singlet triply bridged structure, is very favorable energetically with respect to loss of a CO group, disproportionation into [Cp 2 Mn 2 (CS) 2 (CO) 2 ] + [(Cp) 2 Mn 2 (CS) 2 ], and dissociation into mononuclear fragments. The lowest energy structure for [Cp 2 Mn 2 (CS) 2 ] is a triplet structure with two bridging CS groups and the Mn≡Mn triple bond required to give each Mn atom a 17‐electron configuration for a binuclear triplet. A higher energy singlet [Cp 2 Mn 2 (CS) 2 ] structure is found with a very short MnblablaMn distance of about 2.1 Å suggesting the formal quadruple bond required to give each Mn atom the favored 18‐electron configuration. In other higher energy singlet and triplet [Cp 2 Mn 2 (CS) 2 ] structures the two CS ligands have coupled to form an acetylenedithiolate ligand bridging the two manganese atoms.