TY - JOUR
T1 - Oxidative Verknüpfung von Phosphinomethanidliganden an Titanocen- und Bismutzentren
T2 - selektive CC-, PC- und PP-Bindungsbildung
AU - Karsch, Hans H.
AU - Deubelly, Brigitte
AU - Grauvogl, Gregor
AU - Müller, Gerhard
PY - 1993/10/19
Y1 - 1993/10/19
N2 - The reaction of Cp2TiCl2 with two equivalents of Lithium-phosphinornethanides is described. The reaction with LiCH2PMe2 leads to a CC coupling product Cp2Ti[Me2PCH2CH2PMe2], whereas with {(TMEDA)Li[CH(PMe2)(SiMe3)]}2, the PC coupling product Me3SiCH2PMe2C(PMe2)(SiMe3), a P-ylide, is formed. An anlogous PC coupling is observed with Li[CH(PMe2)2], whereby a novel titanocene heterocycle {Cp2Ti(H)[(Me2P)2CPMe2CH2 PMe2)]}, with an agostic Ti ⋯ H ⋯ C interaction, may be characterized as an intermediate. In contrast, with Li[CH(PMe2)(SiMe 3)] (without TMEDA) PP coupling, yielding [(Me3Si)(H)CPMe2]2, is observed exclusively. An analogous result is obtained with Li[C(PMe2)(SiMe3)2], leading to [(Me3Si)2CPMe2]2, and, likewise, in the similar reaction of Cp2TiCl2 with Li[C(PMe2)2(SiMe3)], PP coupling is observed leading to [(Me2P)(Me3Si)CPMe2]2 and {Cp2TiIII [(Me2P)2C(SiMe3)]}. With (TMEDA)Li[HC(PPh2)2], both PP (34%) and PC (66%) coupling are observed, yielding the P-ylides [(Ph2P)HCPPh2]2 and Ph2PCH2PPh2C(PPh2)2, respectively. The results are compared with the respective coupling reactions at bismuth centers: BiCl3 reacts with LiCH2PMe2 to give Bi(CH2PMe2)3; with {(TMEDA)Li[CH(PMe2)(SiMe3)]}2 only 5% of the PC coupling product Me3SiCH2PMe2C(PMe2)(SiMe3) are found, whereas 95% of the PP coupling product [(Me3Si)(H)CPMe2]2 are obtained. Exclusive PP coupling is also observed from BiCl3 and (TMEDA)Li[C(PMe2)(SiMe3)2] and Li[C(PMe2)2(SiMe3)], respectively. The results clearly indicate that a metal-centered process, sensitive to steric and coordination effects, is active. Selective CC, PC and P P coupling reactions are possible by selecting the appropriate combinations of reagents. The novel P-ylides are characterized by use of NMR spectroscopy; {Cp2TiIII [(Me2P)2C(SiMe3)]} and [(Me3Si)2CPMe2]2 are further characterized by X-ray structure determinations.
AB - The reaction of Cp2TiCl2 with two equivalents of Lithium-phosphinornethanides is described. The reaction with LiCH2PMe2 leads to a CC coupling product Cp2Ti[Me2PCH2CH2PMe2], whereas with {(TMEDA)Li[CH(PMe2)(SiMe3)]}2, the PC coupling product Me3SiCH2PMe2C(PMe2)(SiMe3), a P-ylide, is formed. An anlogous PC coupling is observed with Li[CH(PMe2)2], whereby a novel titanocene heterocycle {Cp2Ti(H)[(Me2P)2CPMe2CH2 PMe2)]}, with an agostic Ti ⋯ H ⋯ C interaction, may be characterized as an intermediate. In contrast, with Li[CH(PMe2)(SiMe 3)] (without TMEDA) PP coupling, yielding [(Me3Si)(H)CPMe2]2, is observed exclusively. An analogous result is obtained with Li[C(PMe2)(SiMe3)2], leading to [(Me3Si)2CPMe2]2, and, likewise, in the similar reaction of Cp2TiCl2 with Li[C(PMe2)2(SiMe3)], PP coupling is observed leading to [(Me2P)(Me3Si)CPMe2]2 and {Cp2TiIII [(Me2P)2C(SiMe3)]}. With (TMEDA)Li[HC(PPh2)2], both PP (34%) and PC (66%) coupling are observed, yielding the P-ylides [(Ph2P)HCPPh2]2 and Ph2PCH2PPh2C(PPh2)2, respectively. The results are compared with the respective coupling reactions at bismuth centers: BiCl3 reacts with LiCH2PMe2 to give Bi(CH2PMe2)3; with {(TMEDA)Li[CH(PMe2)(SiMe3)]}2 only 5% of the PC coupling product Me3SiCH2PMe2C(PMe2)(SiMe3) are found, whereas 95% of the PP coupling product [(Me3Si)(H)CPMe2]2 are obtained. Exclusive PP coupling is also observed from BiCl3 and (TMEDA)Li[C(PMe2)(SiMe3)2] and Li[C(PMe2)2(SiMe3)], respectively. The results clearly indicate that a metal-centered process, sensitive to steric and coordination effects, is active. Selective CC, PC and P P coupling reactions are possible by selecting the appropriate combinations of reagents. The novel P-ylides are characterized by use of NMR spectroscopy; {Cp2TiIII [(Me2P)2C(SiMe3)]} and [(Me3Si)2CPMe2]2 are further characterized by X-ray structure determinations.
UR - http://www.scopus.com/inward/record.url?scp=0001855046&partnerID=8YFLogxK
U2 - 10.1016/0022-328X(93)86060-U
DO - 10.1016/0022-328X(93)86060-U
M3 - Artikel
AN - SCOPUS:0001855046
SN - 0022-328X
VL - 459
SP - 95
EP - 105
JO - Journal of Organometallic Chemistry
JF - Journal of Organometallic Chemistry
IS - 1-2
ER -