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Versatile Phosphite Ligands Based on Silsesquioxane Backbones
Author(s) -
van der Vlugt Jarl Ivar,
Ackerstaff Jens,
Dijkstra Tessa W.,
Mills Allison M.,
Kooijman Huub,
Spek Anthony L.,
Meetsma Auke,
Abbenhuis Hendrikus C. L.,
Vogt Dieter
Publication year - 2004
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.200303186
Subject(s) - silsesquioxane , chemistry , denticity , ligand (biochemistry) , hydroformylation , rhodium , biphenyl , nuclear magnetic resonance spectroscopy , medicinal chemistry , stereochemistry , phosphoramidite , crystallography , catalysis , polymer chemistry , organic chemistry , crystal structure , dna , biochemistry , receptor , oligonucleotide , polymer
Abstract Silsesquioxanes are employed as ligand backbones for the synthesis of novel phosphite compounds with 3,3′‐5,5′‐tetrakis( tert ‐butyl)‐2,2′‐dioxa‐1,1′‐biphenyl substituents. Both mono‐ and bidentate phosphites are prepared in good yields. Two types of silsesquioxanes are employed as starting materials. The monophosphinite 1 and the monophosphite 2 are prepared from the thallium silsesquioxide derived from a completely condensed silsesquioxane framework ( c ‐C 5 H 9 ) 7 Si 7 O 12 SiOTl. The diphosphite 3 is synthesized starting with the incompletely condensed monosilylated disilanol ( c ‐C 5 H 9 ) 7 Si 7 O 9 (OSiMePh 2 )(OH) 2 . For monophosphite 2 , the corresponding trans ‐[PtCl 2 ( 2 )] complex 4 is characterized by NMR spectroscopy as well as by X‐ray crystallography, as the first example of a completely condensed oxo‐functionalized silsesquioxane framework. The coordination of the bidentate ligand 3 towards Pd, Mo and Rh is studied, both by NMR spectroscopy as well as by X‐ray crystallography. Various modes of coordination are shown to be possible. The molecular structures for the complexes trans ‐[PdCl 2 ( 3 )] ( 5 ), cis ‐[Mo(CO) 4 ( 3 )] ( 6 ) and the dinuclear complex [{Rh(μ‐Cl)(CO)} 2 (κ 2 ‐ 3 )] ( 7 ) have been determined. In the rhodium‐catalyzed hydroformylation of 1‐octene high activities, with turnover frequencies of up to 6800 h −1 , are obtained with these new nanosized phosphorus ligands.