Chiral Self‐Recognition between Stereogenic Tetrapalladium Units Affording Pd8 Chains Supported by Homochiral Tetraphosphines. Issue 3 (22nd November 2016)

• Record Type: Journal Article
• Authors: Tanase, Tomoaki; Morita, Konomi; Otaki, Risa; Yamamoto, Kana; Kaneko, Yukino; Nakamae, Kanako; Kure, Bunsho; Nakajima, Takayuki
• Is Part Of: Chemistry. Volume 23:Issue 3(2017)
• Page Start: 524
• Page End: 528
• Publication Date: 2016-11-22
• Subjects: chiral self-recognition -- metal atom chains -- octanuclear complexes -- palladium -- tetraphosphines; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201605146
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: By using a chiral tetraphosphine, rac ‐bis[(diphenylphosphinomethyl)phenylphosphino]methane ( rac ‐dpmppm), linear octapalladium chains were synthesized as discrete molecules of [Pd8 (μ‐ rac ‐dpmppm)4 L2 ](BF4 )4 (L=CH3 CN, dmf, XylNC), [Pd8 (μ‐ rac ‐dpmppm)4 ](BF4 )4, and [Pd8 (μ‐ rac ‐dpmppm)4 (Cl)2 ](BF4 )2, which are stable in the solution states and characterized by spectroscopic and crystallographic methods to reveal the octapalladium chains supported by homochiral four tetraphosphines. Variable‐temperature NMR studies for a 1:1 mixture of [Pd8 (μ‐ rac ‐dpmppm)4 (dmf)2 ](BF4 )4 and [Pd8 (μ‐ meso ‐dpmppm)4 (dmf)2 ]‐(BF4 )4 in [D7 ]DMF revealed that the Pd8 chains were dissociated at higher temperature ( T ≈140 °C) into the Pd4 units of {Pd4 (μ‐ rac ‐dpmppm)2 } 2+ and {Pd4 (μ‐ meso ‐dpmppm)2 } 2+, and they were thermodynamically self‐aligned to restore the Pd8 chains at lower temperature ( T <60 °C), through perfect chiral self‐recognition between the stereogenic tetrapalladium units. Abstract : Palladium pearls : Linear Pd4 building blocks, {Pd4 ( rac ‐dpmppm)2 } 2+ and {Pd4 ( meso ‐dpmppm)2 } 2+, were thermodynamically self‐aligned to generate Pd8 chains with homochiral dpmppm ligands, {Pd8 ( rac ‐dpmppm)4 } 4+ and {Pd8 ( meso ‐dpmppm)4 } 4+, through chiral self‐recognition between the stereogenic Pd4 units.