Degree Type

Dissertation

Date of Award

1989

Degree Name

Doctor of Philosophy

Department

Chemistry

First Advisor

Robert Angelici

Abstract

This dissertation describes the synthesis and reactions of tungsten thiocarbonyl, thiocarbyne and thiocarbene complexes. Treatment of Bu[subscript]4N (HB(pz)[subscript]3) (CO)[subscript]2W(CS) (HB(pz)[subscript]3[superscript]- is the tris (1-pyrazolyl)borato ligand) with (([eta][superscript]5-C[subscript]9H[subscript]7)Mo(CO)[subscript]2(MeCN)[subscript]2) BF[subscript]4 gives the neutral W-Mo bonded dimer (HB(pz)[subscript]3) (CO)[subscript]2W([mu]-CS)Mo([eta][superscript]5-C[subscript]9H[subscript]7)(CO)[subscript]2. A single-crystal X-ray diffraction study shows that the molybdenum atom achieves an 18-electron configuration by accepting [pi]-electron density from the thiocarbonyl ligand which is also bonded via the carbon to the tungsten. This is the first example of a complex containing a four-electron donating, side-on bridging thiocarbonyl ligand. The thiocarbonyl complex (HC(pz)[subscript]3) (CO)[subscript]2W(CS) is prepared by the reaction of trans-IW(CO)[subscript]4(CS)[superscript]- with HC(pz)[subscript]3. The nucleophilic sulfur atom of the CS ligand can be methylated with Me[subscript]3O[superscript]+ to give the thiocarbyne (HC(pz)[subscript]3) (CO)[subscript]2W≡C-SMe[superscript]+. Reaction of the carbyne with phosphorus nucleophiles (PR[subscript]3) gives the [eta][superscript]2-ketenyl derivatives (HC(pz)[subscript]3) (CO) (R[subscript]3P)[overline]W[C(O)CSMe][superscript]+. Protonation of the carbyne with HBF[subscript]4· Et[subscript]2O produces the [eta][superscript]2-carbene (HC(pz)[subscript]3] (CO)[subscript]2[overline]W[[eta][superscript]2-CH(SMe)] [superscript]2+, which reacts with PR[subscript]3, RS[superscript]- and H[superscript]- nucleophiles to give the carbene adducts (HC(pz)[subscript]3] (CO)[subscript]2[overline]W[[eta][superscript]2-CH(L)(SMe)][superscript] n+. The SMe[superscript]+ electrophile adds to the carbyne carbon of (HB(pz)[subscript]3) (CO)[subscript]2W≡C-SMe, to give (HB(pz)[subscript]3] (CO)[subscript]2[overline]W[[eta][superscript]2-C(SMe)SMe][superscript]+, containing an [eta][superscript]2-dithiocarbene ligand bonded to the metal through both the carbon and one of the sulfur atoms. Reactions of the dithiocarbene complex with nucleophiles (Nuc) give the air stable adducts (HB(pz)[subscript]3] (CO)[subscript]2[overline]W[[eta][superscript]2-C(SMe)(Nuc)SMe] (Nuc = SR, H, CH[subscript]3 and PMe[subscript]3). Heating the MeS[superscript]- dithiocarbene adduct (HB(pz)[subscript]3] (CO)[subscript]2[overline]W[[eta][superscript]2-C(SMe)[subscript]2SMe] above 60 °C results in the loss of CO and C-S bond cleavage, giving the carbyne (HB(pz)[subscript]3) (MeS)[subscript]2W≡C-SMe, which was characterized by X-ray analysis. Thermal and photolytic reactions of the other dithiocarbene adducts also give products resulting from C-S bond cleavage.

DOI

https://doi.org/10.31274/rtd-180813-11806

Publisher

Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/

Copyright Owner

Ruth Ann Doyle

Language

en

Proquest ID

AAI8920126

File Format

application/pdf

File Size

159 pages

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