DYNAMIC BEHAVIOR OF TETRAMETHYLETHYLENE DIAMINE (TMEDA) LIGANDS IN SOLID ORGANOLITHIUM COMPOUNDS - A VARIABLE-TEMPERATURE C-13 AND N-15 CP/MAS NMR-STUDY

被引：24

作者：

BAUMANN, W ^{[1
]}

OPRUNENKO, Y ^{[1
]}

GUNTHER, H ^{[1
]}

机构：

[1] UNIV SIEGEN,FACHBEREICH 8,OCII,D-57068 SIEGEN,GERMANY

来源：

ZEITSCHRIFT FUR NATURFORSCHUNG SECTION A-A JOURNAL OF PHYSICAL SCIENCES | 1995年 / 50卷 / 4-5期

关键词：

CP MAS NMR; C-13-NMR; N-15-NMR; LI-7; NMR; DYNAMIC PROCESSES; ORGANOMETALLICS;

D O I：

10.1515/zna-1995-4-516

中图分类号：

O64 [物理化学（理论化学）、化学物理学];

学科分类号：

070304 ; 081704 ;

摘要：

The dynamic behaviour of tetramethylethylene diamine (TMEDA) ligands in three organometallic complexes, dimeric phenyllithium, [Li(tmeda)mu-Ph](2) (1), lithium cyclopentadienide, [Li(tmeda)]C5H5 (2), and dilithium naphthalendiide, trans-[Li(tmeda)]2C10H8 (3), has been studied by CP/MAS C-13 and N-15 as well as Li-7 MAS NMR spectroscopy of powdered samples. Two dynamic processes with free activation enthalpies of 40 and 68 kJ mol(-1), respectively, were detected for 1. The first one can be assigned to ring inversion of the five-membered Li-TMEDA rings, while the second is caused by a complete rotation of the TMEDA- ligands or a ring inversion of the central four membered C-Li-C-Li metallacycle. Fast rotation of the ligands on the NMR time scale was found for 2, while 3 shows 180 degrees ring flips of the Li-TMEDA groups, which are characterized by an energy barrier Delta G(not equal)(317) of 64 kJ mol(-1).

引用

页码：429 / 438

页数：10

共 48 条

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