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η 1 ‐P‐ und η 2 ‐OP‐gebundene (Ether‐phosphan)osmium(II)‐Komplexe und ihre gegenseitige Umwandlung
Author(s) -
Lindner Ekkehard,
Rothfuß Helmut,
Fawzi Riad,
Hiller Wolfgang
Publication year - 1992
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.19921250303
Subject(s) - chemistry , osmium , ether , medicinal chemistry , denticity , stereochemistry , chelation , cis–trans isomerism , metal , dissociation (chemistry) , crystal structure , crystallography , catalysis , ruthenium , inorganic chemistry , biochemistry , organic chemistry
η 1 ‐P‐ and η 2 ‐O P‐Bonded (Ether‐Phosphane)Osmium(II) Complexes and their Mutual Conversion Reactions of cis ‐Br 2 Os(CO) 4 with the (ether‐phosphane) ligands 2a–f results in the formation of the cis,cis,trans ‐complexes Br 2 Os(CO) 2 (P ∼ O) 2 ( 3a–f ). 3b crystallizes in the mono‐clinic space group P 2 1 /c with Z = 4. Irradiation of 3a–f leads to the cleavage of a further CO group and the formation of an OsO bond to give the mono(chelate) complexes Br 2 Os(CO)‐(PO) PO ( 5a–f ), with one of the O,P ligands being bidentate. 5a–f exist as mixtures of different trans ‐P ( A,B ) and cis ‐P isomers ( C–G ). Dependent on the fact that a reversible cis/trans equilibrium or an irreversible trans → cis transformation is possible or that no trans ‐P isomers are present at any temperature, 5a–f may be classified in three categories. Inter‐conversion of the isomers A–G results from dissociation of the η 1 ‐P coordinated ether‐phosphane and concomitant occurrence of the 16e − species Br 2 Os(CO)(PO) ( 8 ). From temperature‐dependent 31 P{ 1 H}‐NMR spectroscopic investigations the temperature for the reversible opening of the metal‐oxygen contact is determined. The reversible opening leads to the complexes Br 2 Os(CO)(PO) 2 ( 9 ) with a vacant coordination site depending on the Os–O bonding strength. 5a–f react with CO to give all‐trans ‐Br 2 Os(CO) 2 (PO) 2 ( 4a–f ). The action of the ether‐phosphanes 2a–f on OsBr 2 (PPh 3 ) 4 ( 7 ) affords the bis(chelate) complexes Br 2 Os(PO) 2 ( 6a–f ) which add carbon monoxide to form all‐trans ‐ 4a–f .