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1,1′‐Bis(diphenylphosphino)bicyclopropyl: Synthesis, Properties, Precursors, Derivatives, and Metal Complexes
Author(s) -
Dziwok Klaus,
Lachmann Joachim,
Wilkinson Dallas L.,
Müller Gerhard,
Schmidbaur Hubert
Publication year - 1990
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19901230303
Subject(s) - chemistry , ligand (biochemistry) , adduct , tetrahydrofuran , dehydrohalogenation , rhodium , borane , metal , ionic bonding , stereochemistry , medicinal chemistry , transition metal , molecule , cyclopropanation , crystallography , organic chemistry , catalysis , ion , biochemistry , receptor , solvent
The title compound 4 has been prepared from readily available 2,3‐bis(diphenylphosphinyl)‐1,3‐butadiene ( 1 ) through double cyclopropanation using Me 2 S(CH 2 )O to give 1,1′‐bis(diphenylphosphinyl)bicyclopropyl ( 2 ), followed by reduction using HSiCl 3 /NEt 3 . Addition of sulfur to compound 4 yields the disulfide 5 , and reaction with tetrahydrofuran – borane affords the 1:2 adduct with BH 3 ( 6 ). Quaternization reactions with MeI or CH 2 I 2 give the double quaternary salts 7 and 8 , respectively. Single dehydrohalogenation employing n BuLi converts 8 into the cyclic semiylide salt 9. 4 is an excellent ligand for lowvalent late transition‐metal cations. With PdI 2 the 1:1 complex LPdI 2 ( 10 , with L = 4 ), and with [(CO) 2 RhCl] 2 the ionic 2:1 complex L 2 Rh + Cl ‐ ( 11 ) are obtained. Experiments with (CO)AuCl yield the 1:2 complex L(AuCl) 2 ( 12 ), X‐ray structure analyses were performed with single crystals of the disulfide 5 , as well as the rhodium(I) and gold(I) complexes 11 and 12. 5 has a conformation between s‐cis and s‐trans with the PS functions pointing away from each other at opposite ends of the molecule. By contrast, in the gold(I) complex the ligand approaches an s‐cis conformation, and through rotations about P–C and C–C bonds – as referred to the conformation of 5 – the metal atoms are brought into close contact: Au … Au = 3.085 Å. Through temperature‐dependent NMR investigations of compounds 5 and 12 , and by comparison with values calculated or experimentally determined for related bicyclopropyl compounds (available in the literature), the energy of the Au … Au attraction has been estimated to be ca. 6 kcal/mol. Compound 11 features a square‐planar, double‐chelate cation.