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Investigations on the Steric Accessibility of the Carbanionic Moiety in Zwitterionic Magnesium Tris(pyrazolyl)methanide Complexes. Synthesis and Characterisation of Bi‐ and Trimetallic Complexes
Author(s) -
Meyer Jens,
Kuzu Istemi,
GonzálezGallardo Sandra,
Breher Frank
Publication year - 2013
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.201200405
Subject(s) - steric effects , chemistry , adduct , moiety , tris , carbanion , phosphine , lewis acids and bases , ligand (biochemistry) , stereochemistry , metal , crystallography , carboxylate , medicinal chemistry , organic chemistry , biochemistry , receptor , catalysis
Reactions of HC(pz) 3 and HC(4‐Mepz) 3 with MgBu 2 and Mg{N(SiMe 3 ) 2 } 2 gave the zwitterionic complexes [Mg{C(pz) 3 } 2 ] ( 2 ) and [Mg{C(4‐Mepz) 3 } 2 ] ( 4 ), respectively, containing “free” pyramidal carbanions (pz = pyrazolyl). The solid‐state structure of 2 has been determined. Reactions of 2 and 4 as well as the recently reported homo‐ and heteroleptic complexes [Mg{C(3, 5‐Me 2 pz) 3 } 2 ] ( 1 ) and [Mg{C(3, 5‐Me 2 pz) 3 }{C(pz) 3 }] ( 3 ) with the Lewis acid AlEt 3 furnished the bi‐ and trimetallic complexes [Mg{C(pz) 3 } 2 (AlEt 3 ) 2 ] ( 5 ), [Mg{C(pz) 3 }(AlEt 3 ){C(3, 5‐Me 2 pz) 3 }] ( 6 ), and [Mg{C(4‐Mepz) 3 } 2 (AlEt 3 ) 2 ] ( 7 ). Based on NMR spectroscopic investigations, including an X‐ray structural analysis on single crystals of 5 , only the parent tris(pyrazolyl)methanide {C(pz) 3 } – and the 4‐methyl‐substituted ligand scaffolds form C ‐bound adducts with the Lewis acid. By quantifying the steric bulk of κ 3 N ‐coordinated {C(pz) 3 } – it could be shown that its steric features are similar to those of bulky phosphine ligands.