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Homo‐ and Heterodinuclear Rh and Ir Complexes Supported by SN n Mixed‐Donor Ligands ( n = 2–4): Stereochemistry and Coordination‐Site‐Exchange Reactions of Cp*M (M = Rh, Ir) Units
Author(s) -
Nakajima Takayuki,
Kawasaki Yuki,
Kure Bunsho,
Tanase Tomoaki
Publication year - 2016
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.201600722
Subject(s) - chemistry , moiety , stereochemistry , diastereomer , amine gas treating , acetonitrile , crystallography , rhodium , medicinal chemistry , catalysis , biochemistry , organic chemistry , chromatography
A series of SN n mixed‐donor ligands [ n = 2: H 2 NC 2 H 4 SCH 2 ‐2‐pyridyl (2‐NSpy) ( 1a ), H 2 NC 2 H 4 SCH 2 ‐4‐pyridyl (4‐NSpy) ( 1b ), n = 3: 2‐pyridylCH 2 NHC 2 H 4 SCH 2 ‐2‐pyridyl (2‐pyNSpy) ( 2 ), n = 4: (2‐pyridylCH 2 ) 2 NC 2 H 4 SCH 2 ‐2‐pyridyl (2‐py 2 NSpy) ( 3 )] was utilized to support homo‐ and heterodinuclear complexes including Cp*M III units (M = Rh, Ir; Cp* = pentamethylcyclopentadienyl). Reactions of [Cp*MCl 2 ] 2 with 2‐pyNSpy ( 2 ), 2‐py 2 NSpy ( 3 ), and 4‐NSpy ( 1b ) afforded homodinulear complexes, [(Cp*MCl)(2‐pyNSpy)(Cp*MCl)](PF 6 ) 2 [M = Rh ( 5a ), Ir ( 5b )], [(Cp*M)(2‐py 2 NSpy)(Cp*MCl)](PF 6 ) 3 [M = Rh ( 6a ), Ir ( 6b )], [(Cp*MCl)(4‐NSpy)(Cp*MCl 2 )]Cl [M = Rh ( 8a ), Ir ( 8b )]. Heterodinuclear complexes [(Cp*MCl)(4‐NSpy)(Cp*M ′ Cl 2 )]Cl [M, M′ = Rh, Ir ( 8c ), Ir, Rh ( 8d )] were prepared using mononuclear complexes [(Cp*MCl)(4‐NSpy)]Cl [M = Rh ( 7a ), Ir ( 7b )] reacted with [Cp*MCl 2 ] 2 (M = Ir, Rh), respectively. Complexes 5 – 8 were characterized by X‐ray crystallography to determine the configurations around the M, M′, S, and N centers. The solid‐state structures of 6 are retained in acetonitrile solution whereas four diastereomers are generated in the case of 5 due to low stereoselectivity around the coordinated amine nitrogen atom, in contrast to the sulfur atom. Heterodinuclear complexes 8c , d are unstable in solution at 55 °C, readily affording mixtures of 8a – d via intra‐ and intermolecular coordination‐site‐exchange reactions of Cp*M fragments between the SN moiety and the py site. In order to evaluate the selectivity of Cp*M fragments for the SN and py coordination sites, several competitive reactions of [Cp*MCl 2 ] 2 (M = Rh, Ir) with H 2 NC 2 H 4 SCH 2 C 6 H 5 (NSph) ( 4 ) and/or 4‐methylpyridine (4‐Mepy) were carried out to demonstrate predominant formation of iridium complexes 9b and 10b among [(Cp*MCl)(NSph)]Cl [M = Rh ( 9a ), Ir ( 9b )] and [(Cp*MCl)(4‐Mepy)]Cl [M = Rh ( 10a ), Ir ( 10b )]. These reactions indicated higher affinity of the Cp*Ir fragment to both the NS and py sites relative to the rhodium analogue.