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Transition metal complexes of chromium, molybdenum, tungsten, and manganese containing {eta}{sup 1}(S)-2,5-dimethylthiophene, benzothiophene, and dibenzothiophene ligands

Journal Article · · Organometallics
DOI:https://doi.org/10.1021/om990322f· OSTI ID:20013595
Ultraviolet photolysis of hexanes solutions containing the complexes M(CO){sub 6} (M = Cr, Mo, W) or CpMn(CO){sub 3}(Cp = {eta}{sup 5}{minus}C{sub 5}H{sub 5}) and excess thiophene (T*)(T* = 2,5-dimethylthiophene (2,5-Me{sub 2}T), benzothiophene (BT), or dibenzothiophene (DBT)) produces the {eta}{sup 1}(S)=T* complexes (CO){sub 5}M({eta}{sup 1}(S)-T*) 1--8 or Cp(CO){sub 2}Mn({eta}{sup 1}(S)-T*) 9--11, respectively. However, when T* = DBT and M = Mo, a mixture of two products results, which includes (CO){sub 5}Mo({eta}{sup 1}(S)-DBT), 4a, and the {pi}-complex (CO){sub 3}Mo({eta}{sup 6}-DBT), 4b, as detected by {sup 1}H NMR spectroscopy. Only the complexes (CO){sub 5}W({eta}{sup 1}(S)-DBT) (1), (CO){sub 5}Cr({eta}{sup 1}(S)-DBT) (5), and Cp(CO){sub 2}Mn({eta}{sup 1}(S)-DBT) (9) were sufficiently stable (several days) to be isolated and characterized by elemental analyses. Rates of DBT ligand displacement by co (1 atm) at room temperature decreased in the order 5 > 1 > 9. Single-crystal, X-ray structural determinations are reported for 1, 5, and 9. The tilt angle ({phi}) of the DBT ligand in these and related complexes is discussed in terms of {pi}-back-bonding to the DBT ligand.
Research Organization:
Iowa State Univ., Ames, IA (US)
Sponsoring Organization:
US Department of Energy
DOE Contract Number:
W-7405-ENG-82
OSTI ID:
20013595
Journal Information:
Organometallics, Journal Name: Organometallics Journal Issue: 20 Vol. 18; ISSN ORGND7; ISSN 0276-7333
Country of Publication:
United States
Language:
English