216060-73-0Relevant academic research and scientific papers
Trinuclear clusters of osmium containing monodentate, chelating and orthometallated forms of 2,2′-bis(diphenyIphosphino)-1,1′-binaphthyl (BINAP)
Deeming, Antony J.,Stchedroff, Marc
, p. 3819 - 3824 (2007/10/03)
The trinuclear cluster [Os3(CO)11{(A)-BINAP}] 1 containing monodentate (R)-BINAP is formed by thermal treatment of [Os3(CO)12] with 2,2′-bis(diphenylphosphino)-1,1′-binaphthyl, (R)-BINAP. This complex decarbonylates thermally to give the cluster [Os3(CO)10{(R)-BINAP}] 2, which was shown spectroscopically to contain chelating BINAP. On further thermal decarbonylation orthometallation at a phenyl group takes place to give [Os3(μ-H)(CO)8{μ3-(R)-BINAP - H}] 3. There is no evidence for restricted rotation about the P-Ph bonds within the PPh2 groups as we have previously observed for [Ru3(μ-OH)2(CO)8{μ-(R)-BINAP}]. This restricted rotation is an effect of crowding and appears to be a distinct property of μ-coordination rather than chelation of BINAP. However, both clusters 1 and 2 are fluxional, but as a result of different processes. Cluster 1 exists as two interconverting isomers 1A and 1B (31P NMR evidence) which we believe have different conformations within the monodentate (R)-BINAP ligand. Our observations are consistent with restricted rotations about the Ph2P-naphthyl bonds. The decacarbonyl cluster 2 has C2 symmetry and shows 13C NMR coalescences consistent with a dynamic merry-go-round motion at the two Os(CO)4 units but not at the Os(CO)2(BINAP) unit. Single-crystal structures of clusters 1 and 3 confirm these two new modes of BINAP coordination.
