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Lithium and Potassium Complexes with dbn‐ and dbu‐Based Enamido Phosphine Ligands: Syntheses and Applications
Author(s) -
Langer Jens,
Grams Samuel,
Puchta Ralph
Publication year - 2017
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201700305
Subject(s) - chemistry , diphosphines , phosphine , medicinal chemistry , deprotonation , rhodium , moiety , nucleophile , tetrahydrofuran , dimethoxyethane , lithium (medication) , alkali metal , stereochemistry , organic chemistry , catalysis , solvent , medicine , ion , electrode , electrolyte , endocrinology
The phosphines 6‐diphenylphosphino‐1,8‐diazabicyclo[5.4.0]undec‐7‐ene (dbuPH) and 7‐diphenylposphino‐1,5‐diazabicyclo[4.3.0]non‐5‐ene (dbnPH), containing amidine subunits, were successfully deprotonated by n ‐butyllithium or benzylpotassium. In the presence of Et 2 O or THF, the well‐defined complexes [{Li(dbnP)(Et 2 O)} 2 ] ( 1 ), [{Li(dbuP)(Et 2 O)} 2 ] ( 2 ), [{K(dbnP)(THF)} ∞ ] ( 3b ) and [{K(dbuP)(THF) 2 } 2 ] ( 4 ) were obtained, while in the absence of such donors, polymeric [{K(dbnP)} ∞ ] ( 3a ) was formed. These alkali‐metal derivatives are useful precursors for salt‐metathesis reactions, and they allow the transfer of the enamido phosphine ligands to appropriate transition metals, as demonstrated by the syntheses of the new rhodium complexes [Rh(dbnP)(cod)] ( 5 ) and [Rh(dbuP)(cod)] ( 6 ). The reaction of 1 and 2 with Ph 2 PCl underlined the ambident character of dbnP – and dbuP – as nucleophiles and led to the new diphosphines dbn(PPh 2 ) 2 (two isomers C ‐ 7 and N ‐ 7 ) and dbu(PPh 2 ) 2 ( N‐ 8 ), in which either the carbon or the nitrogen atom of the former enamido moiety was substituted.