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Synthesis of Ir[μ 2 ‐( N ‐ N )]M (M = Ir and Ru) Homo‐ and Heterobimetallic Complexes through a Condensation Reaction of N ‐Amino and Formyl Groups Bound to Mononuclear (η n ‐C n Me n )M Units ( n = 5 for M = Ir; n = 6 for M = Ru)
Author(s) -
Nakao Keisuke,
Choi Gyeongshin,
Konishi Yuki,
Tsurugi Hayato,
Mashima Kazushi
Publication year - 2012
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.201100925
Subject(s) - chemistry , pyridine , iridium , medicinal chemistry , denticity , imine , catalysis , condensation reaction , hydrazone , stereochemistry , crystal structure , crystallography , organic chemistry
Reactions of [{Cp*IrCl(μ‐Cl)} 2 ] (Cp* = η 5 ‐pentamethylcyclopentadienyl) with bidentate pyridine–imine ligands such as 2‐(1‐hydrazonoethyl)pyridine ( L 1 ‐NH 2 ) and 4‐({[1‐(pyridine‐2‐yl)ethylidene]hydrazono}methyl)benzaldehyde ( L 3 ‐CHO), followed by salt exchange, afforded the corresponding iridium mononuclear complexes [Cp*IrCl( L 1 ‐NH 2 )][PF 6 ] ( 1a ‐PF 6 ) and [Cp* IrCl( L 3 ‐CHO)][PF 6 ] ( 6 ‐PF 6 ) that bear N ‐amino and formyl functionalities, whereas the reaction of [{Cp*IrCl(μ‐Cl)} 2 ] with butane‐2,3‐diylidenebis(hydrazone) [ L 2 ‐(NH 2 ) 2 ; 2 equiv.] afforded the half‐metallocene iridium complex 2 ‐PF 6 with two free amino groups at the 2,5‐positions of an irida‐2,5‐diazacyclopentene skeleton. Post‐functionalization of the N ‐amino groups of 1a ‐PF 6 and 6 ‐PF 6 was accomplished with 3,5‐dimethoxybenzaldehyde in the presence of a catalytic amount of H 2 SO 4 in CH 3 CN heated at reflux. The condensation reaction proceeded to form N ‐imino‐functionalized iridium mononuclear complexes 3 ‐PF 6 and 4 ‐PF 6 . Dinuclearization of complex 1a ‐PF 6 was achieved by a condensation reaction of 1a ‐PF 6 with dialdehydes. Reaction of an N ‐amino functional group of 1a ‐PF 6 with terephthalaldehyde and isophthalaldehyde in the presence of a catalytic amount of H 2 SO 4 gave the corresponding homodinuclear iridium complexes m ‐ 5 ‐PF 6 and p ‐ 5 ‐PF 6 in high yield. The molecular structure of p ‐ 5 ‐PF 6 , evaluated by X‐ray diffraction study, revealed that two {Cp*IrCl} fragments coordinated to the tetradentate linked hydrazonoethyl skeleton in an anti fashion. Furthermore, treatment of the formyl group of iridium complex 6 ‐PF 6 with the N ‐amino group of ruthenium complex 1b ‐PF 6 resulted in the selective formation of an Ir[μ 2 ‐( N ‐ N )]Ru heterobimetallic complex ( 7 ‐PF 6 ) under similar reaction conditions. The selectivity for the formation of the Ru–Ir heterobimetallic complex was due to the tolerance of the imine moiety to hydrolysis under acidic conditions.