M. Hariharasarma, C. H. Lake, C. Watkins
May 31, 1999
Citations
0
Influential Citations
35
Citations
Journal
Journal of Organometallic Chemistry
Abstract
Abstract Chlorodiphenylphosphine and 2,2′-biphenylylenephosphorochloridite react with 2-hydroxy-2′-(1,4-bisoxo-6-hexanol)-1,1′-biphenyl to yield the new α,ω-bis(phosphorus-donor)-polyether ligands, 2-Ph 2 PO(CH 2 CH 2 O) 2 –C 12 H 8 -2′-OPPh 2 ( 1 ) and 2-(2,2′-O 2 C 12 H 8 )P(CH 2 CH 2 O) 2 –C 12 H 8 -2′-P(2,2′-O 2 C 12 H 8 ) ( 2 ). These ligands react with Mo(CO) 4 (nbd) to form the monomeric metallacrown ethers, cis -Mo(CO) 4 {2-Ph 2 PO(CH 2 CH 2 O) 2 –C 12 H 8 -2′-OPPh 2 } ( cis - 3 ) and cis -Mo(CO) 4 {2-(2,2′-O 2 C 12 H 8 )P(CH 2 CH 2 O) 2 –C 12 H 8 -2′-P(2,2′-O 2 C 12 H 8 )} ( cis - 4 ), in good yields. The X-ray crystal structures of cis - 3 and cis - 4 are significantly different, especially in the conformation of the metal center and the adjacent ethylene group. The very different 13 C-NMR coordination chemical shifts of this ethylene group in cis - 3 and cis - 4 suggest that the solution conformations of these metallacrown ethers are also quite different. Both metallacrown ethers undergo cis – trans isomerization in the presence of HgCl 2 . Although the cis – trans equilibrium constants for the isomerization reactions are nearly identical, the isomerization of cis - 3 is more rapid. Phenyl lithium reacts with cis - 3 to form the corresponding benzoyl complexes but does not react with either trans - 3 or cis - 4 . Both the slower rate of cis – trans isomerization of cis - 4 and its lack of reaction with PhLi are consistent with weaker interactions between the hard metal cations and the carbonyl oxygens in both trans - 3 and cis - 4 .