Alkali metal complexes having sterically bulky bis-iminopyrrolyl ligands – control of dimeric to monomeric complexes. Issue 84 (26th August 2016)

• Record Type: Journal Article
• Authors: Anga, Srinivas; Banerjee, Indrani; Nayek, Hari Pada; Panda, Tarun K.
• Is Part Of: RSC advances. Volume 6:Issue 84(2016)
• Page Start: 80916
• Page End: 80923
• Publication Date: 2016-08-26
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c6ra13437h
• Languages: English
• ISSNs: 2046-2069

Abstract

Abstract : Alkali metal salts of {(CHPh2 )2 -pyr} and {(CPh3 )2 -pyr} were prepared and in the molecular structures of these complexes a nuclearity shift from the dimer to monomer were observed due to the substitutions of CHPh2 to CPh3 groups in imine nitrogen of the ligand. Abstract : We report the syntheses and structural diversity of three different bis-iminopyrrole ligands and their alkali metal (Li, Na, K) complexes featuring a shift from dimeric to monomeric nature by a simple tuning of the steric control of the imine nitrogen substitutions. The bis-iminopyrrole ligands having the molecular formula [(ArNCH)2 C4 H2 NH] [Ar = CHPh2 (1-H ), Ad (2-H ), Ad = adamentyl, and CPh3 (3-H )], were prepared through the reaction of 2, 5-pyrrole-dicarbaldehyde with corresponding amines (ArNH2 ) in a 1 : 2 molar ratio and under acidic conditions. Using ligand1-H, the lithium [{Li(Ph2 CHNCH)2 C4 H2 N}2 ] (1-Li ), sodium [{Na(Ph2 CH–NCH)2 C4 H2 N}2 (THF)] (1-Na ) and potassium [{κ 3 -(Ph2 CHNCH)2 C4 H2 N}-K(THF)2 ] (1-K ) complexes were obtained through either alkane elimination (for Li) or amine elimination (for Na, K). The alkali metal complexes [{κ 2 -(Ph3 CHNCH)2 C4 H2 N}M(THF) n ] [ n = 2, M = Li (3-Li ), Na (3-Na ); n = 3, M = K (3-K )] were synthesized using the ligand3-H . Molecular structures of ligands1-3-H, and alkali metal complexes1-Li, 1-Na, 1-K, 3-Li, 3-Na and3-K, in the solid state were established. The complexes1-Li and1-Na were found to be dimeric in the solid state whereas the complexes1-K, 3-Li, 3-Na and3-K were all monomeric – either due to a larger ionic radius (for1-K ) or because of the presence of the bulky triphenylmethyl group on the imine nitrogen.