ISSN:
0009-2940
Keywords:
Chirality
;
Stereogenicity
;
Diastereoselectivity
;
Ligand stereospecificity
;
Metal sulfur complexes
;
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
In order to investigate the stereochemistry of substitution reactions of chiral pseudo-octahedral complexes the chiral thioether-thiolate ligands ‘RS4’-H2 (= HSC6H4SCHRCH2-SC6H4SH) with R = CH3- (5), CH3(CH2)2- (6), HO(CH2)9- (7), and PhCH2- (8) were synthesized by template alkylation of Na2[Ni(‘S2’)2] [‘S2’2- = 1,2-benzenedithiolate(2-)] with 1,2-dibromoalkanes BrCHRCH2Br (R = CH3-, 1; R = CH3(CH2)2-, 2; R = HO(CH2)9-, 3; R = PhCH2-, 4) and isolated after hydrolyses. Reactions of ‘RS4’-H2 with [RuCl2(PPh3)3] or [Mo(O)2(acac)2] yielded [Ru(PPh3)2(‘RS4’)] (R = CH3-, 9; R = HO(CH2)9-, 10; R = PhCH2-, 11) and [Mo(O)2(‘MeS4’)] (12). [Ru(PPh3)2(‘MeS4’)] · 2 CH2Cl2 (9 · 2 CH2Cl2) and [Mo(O)2(‘MeS4’)] (12) were characterized by X-ray structure determination. In both complexes, the metal centers are surrounded pseudo-octahedrally by four sulfur donors of the ‘MeS4’ ligand and two cis coligands. The methyl substituent at the stereogenic C* atom of the C2 bridge of the ‘MeS4’ ligands assumes an equatorial position. In addition, the metal centers of these complexes are chirotopic and prostereogenic. Crystal data of 9 · 2 CH2Cl2 in comparison with [Ru(PBu3)2(‘S4’) 11-bis(2-mercaptophenylthio)-1-undecanolato(2-), ‘PhCH2S4’2-1,2-bis(2-mercaptophenylthio)-3-phenylpropanato(2-)] ] and those of 12 in comparison with [Mo(O)2(‘S4’)] show that distances and angles of the coordination cores are not influenced by the substituents on the C2 bridge. Reactions of the [Ru(PPh3)2(‘RS4’)] complexes (9-11) with the achiral substrates CO and PMe3, however, yielded diastereomers of [Ru(PPh3)(L)(‘RS4’)] (L = CO, R = CH3-, 13; L = CO, R = HO(CH2)9-, 14; L = CO, R = PhCH2-, 15; L = PMe3, R = CH3-, 16; L = PM R = HO(CH2)9-, 17; L = PMe3, R = PhCH2-, 18) in diastereomeric excesses between 60 and 82%. The diastereomer of [Ru(PPh3)CO)(‘MeS4’)] (13) which could be characterized by X-ray structure determination exhibits the CO ligand in trans position to the thioether donor which is bound to the stereogenic C* atom of the C2 bridge. Reaction of 9 · 2 CH2Cl2 with the optically pure bidentate diphosphine (+)-(S,S)-DIOP [= (+)-2,3-O-isopropylidene-2,3-dihydroxy-1,4-bis(diphenylphosphino)butane] yielded 1:1 mixtures of two diastereomers of [Ru(DIOP)(‘MeS4’)] (19) one of which was separated in pure form by HPLC.
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cber.19951280702
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