- Chirale tripodliganden mit phosphor- uni schwefeldonoren. synthese und komplexchemie chiral tripod ligands with phosphorus and sulfur donors. Synthesis and complex chemistry
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Neopentane based tripod licands CH3C(CH2X)(CH2Y)(CH2Z) with mixed donor groups X,Y,Z (PR2, SR, SH) are accessible via two different strategies. The functionalized thietane CH3(CH2X)tCH2SCH2 allows stepwise introduction of P or S donors by substitution of the mesylate function and subsequent nucleophilic cleavage of the thietane ring. Tripod ligands 5 [CH3C(CH2X)(CH2Y)(CH2Z)j with up to three different donor groups (X = SH; Y = PPh2; Z = P;4-Tol)2, SCH2Ph, PPh2 are thus available. As an alternative the neopentano aerivatives 8 [CH3C;CH2X)(CH2Y)(CH2C1)] which are easily assessible from CH3C(CH2OSO2Me)(CH2BrJ(CH 2Cl) (7) by stepwise substitution with phosphides LiPAr2 (Ar = aryl) may be transiormed to 9 [CH3C(CH2X)(CH2Y)(CH2SBzl)]. Under controlled condi-tions the S-benzyl bond of 9 is cleaved reductively without concomitant cleavage of P-Ar bonds. Ligand 5a [CH3C(CH2PPh.)2(CH2SH)] reacts with Ni;BF4J26 H2O to yield the dinuclear species [(CH3C(CH2PPh2)2(CH 2S)Ni)2]2+ (10). The two ligands are bonded in an equivalent way with each of the two nickel centers interacting with one of the two phosphane functions of the ligand; the thiolate functions form (i2-SR bridges between the two nickel atoms. The SCH2 group at the four-membered S2Ni2 ring are in mutual cis position with the four-membered ring bent along the sulfur-sulfur axis by 70°. The internal strain in 10 is analyzed by comparing its structure with the ones of [(CH3C(CH2PPh2)2NiSPh) 2j2+ (11) and i(CH3C(CH2OH)(CH2PPh2)2. NiOH}2]2+ (12). VCK Venagsgcsci.schaf: mbH, 1996.
- Reinhard, Gunther,Soltek, Rainer,Huttner, Gottfried,Barth, Annette,Walter, Olaf,Zsolnai, Laszlo
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- Study of Effects on the Coordination of Thioether Ligands, 2. Stereospecific Ligand Substitutions in Manganese (I) Complexes
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Treatment of fac- and fac- with silver hexafluorophosphate yields the η3-tripodal manganese complexes PF6 (7) and PF6 (9), respectively, whereas the reaction of CH3C(CH2PPh2)2(CH2SH) with Mn(CO)5Br gives directly Mn(CO)3 (11).Both ionic complexes 7 and 9 undergo stereospecifically ligand substitution upon treatment with Br(-), I(-), N3(-), SCN(-) and CN(-) to give syn-fac- and syn-fac- (X = Br, I, SCN, N3, CN) respectively, but the neutral complex 11 fails to undergo such a substitution reaction with these ions.However, reaction of I(-) with the complex Mn(CO)3>BF4 (20) , which is obtained from the S-alkylation of 11 with the (CH3)3OBF4, affords syn-fac-Mn(CO)3I (22s) exclusively.The possible reaction mechanism of this ligand substitution is discusssed. - Key Words: Tripodal ligands/ Phosphane ligands/ Thioethers/ Manganese complexes
- Tsai, Shiou-chuan,Wang, Hsin-Ell,Huang, Chi-Tsuan,Yiin, Lih-Ming,Liu, Shiuh-Tzung
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p. 151 - 156
(2007/10/02)
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