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Synthesis and Tunable Reactivity of N‐Heterocyclic Germylene
Author(s) -
Xiong Yun,
Yao Shenglai,
Driess Matthias
Publication year - 2012
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.201200379
Subject(s) - chemistry , reactivity (psychology) , phenylacetylene , yield (engineering) , ligand (biochemistry) , tautomer , medicinal chemistry , nuclear magnetic resonance spectroscopy , stereochemistry , alkyne , crystallography , organic chemistry , catalysis , pathology , medicine , biochemistry , materials science , alternative medicine , receptor , metallurgy
Modifying the β‐diketimine ligand LH 1 (LH=[ArNC(Me)CHC(Me)NHAr], Ar=2,6‐ i Pr 2 C 6 H 3 ) through replacement of the proton in 3‐position by a benzyl group (Bz) leads to the new Bz LH ligand 2, which could be isolated in 77 % yield. According to 1 H NMR spectroscopy, 2 is a mixture of the bis(imino) form [(ArNC(Me)] 2 CH(Bz) 2a and its tautomer [ArNC(Me)C(Bz)C(Me)NHAr] 2b. Nevertheless, lithiation of the mixture of 2a and 2b affords solely the N ‐lithiated β‐diketiminate [ArNC(Me)C(Bz)C(Me)NLiAr], Bz LLi 3. The latter reacts readily with GeCl 2⋅ dioxane to form the chlorogermylene Bz LGeCl 4, which serves as a precursor for a new zwitterionic germylene by dehydrochlorination with LiN(SiMe 3 ) 2 . This reaction leads to the zwitterionic germylene Bz L′Ge: 5 ( Bz L′=ArNC(CH 2 )C(Bz)C(Me)NAr) which could be isolated in 83 % yield. The benzyl group has a distinct influence on the reactivity of zwitterionic 5 in comparison to its benzyl‐free analogue, as shown by the reaction of 5 with phenylacetylene, which yields solely the 1,4‐addition product 6, that is, the alkynyl germylene Bz LGeCCPh. Compounds 2–8 have been fully characterized by multinuclear NMR spectroscopy, mass spectrometry, elemental analyses, and single‐crystal X‐ray diffraction analyses.