Date of Award
1984
Degree Type
Dissertation
Degree Name
Doctor of Philosophy
Abstract
The synthesis of fluorinated-alcohol thioethers of the type HOC(CF(,3))(,2)CH(,2)SR (R=Me,Ph,('t)Bu), is described. These can be deprotonated to give bidentate, uninegative hybrid ligands, denoted L('-), which contain both a hard (alkoxide) and a soft (thioether) donor site (HSAB theory). They favour complex-formation with soft, over hard metal ions: CuL(,2) (R=Me) is the only stable first- row transition metal complex accessible; PdL(,2) and PtL(,2) (R=Me,Ph,('t)Bu) are all stable. By NMR, PtL(,2) is cis, with syn and anti forms from pyramidal sulfur; PdL(,2) is a cis/trans mixture of syn- and anti-isomers. Mixed-ligand complexes of the type {lcub}ML(Cl)PPh(,3){rcub} and {lcub}ML(PR(,3))(,2){rcub}BF(,4) were also prepared, M = Pt(II), Pd(II); PR(,3) = PMe(,3-n)Ph(,n) (n = 0-3); also {lcub}ML(SEt(,2))(,2){rcub}BF(,4). The geometry was established by ('1)H, ('19)F and ('31)P NMR. Large changes;in chemical-shift separation were noted for PME(,3) (--->) PPh(,3). The structural origin of this was sought by the comparative crystal structure determinations of {lcub}Pt{lcub}OC(CF(,3))(,2)CH(,2)SCH(,3){rcub}(PR(,3))(,2){rcub}BF(,4), PR(,3) = PPh(,3), PMePh(,2). They possess approximately square-planar four-coordinate cations. Both have chelate-ring conformations with SCH(,3) anti to the more axial CF(,3) group. Thioether inversion has been studied by DNMR in all these complexes. Metal dependence, angle-strain and steric effects on (DELTA)G('(DBLDAG)) are observed, and explained using the classical mechanism of pyramidal inversion. The chelate rings have a preferred orientation in solution, probably the same as in the solid state. Independent NMR probes provide evidence that sulfur inversion induces chelate-ring inversion. The trans-effect on inversion (order of decreasing (DELTA)G('(DBLDAG))) is: RC(CF(,3))(,2)O('-) < Cl('-) < SR(,2) < PR(,3). However, the NMR trans-influence is shown to be: Cl('-) < RC(CF(,3))(,2)O('-) < SEt(,2) < PR(,3). The reversal in position of chloride and alkoxide is shown to be consistent with the latter forming bonds to Pt(II) with more ionic and less covalent character than the former. Re-investigation of the platinum chemistry of ('-)OC(CF(,3))(,2)C(CF(,3))(,2)O('-), PFP('2-), was undertaken. Complexes of the type Pt(PFP)L(,2) were prepared where L = PMe(,3-n)Ph(,n) (n = 0-3). SMe(,2), MeSEt, OSMe(,2); L(,2) = CH(,3)SCH(,2)CH(,2)SCH(,3). From these, the same reversal of position in the trans-effect and influence series is obtained.
Recommended Citation
Boere, Rene Theodoor, "The Coordination Chemistry Of Fluorinated-alcohol Thioethers" (1984). Digitized Theses. 1362.
https://ir.lib.uwo.ca/digitizedtheses/1362