115940-58-4Relevant academic research and scientific papers
Studies directed toward the synthesis of chiral tungsten and molybdenum carbonyl complexes
Maji, Pathik,Wang, Wei,Greene, Andrew E.,Gimbert, Yves
, p. 1841 - 1849 (2008/09/18)
A major challenge that must be met for an asymmetric intermolecular Pauson-Khand reaction is to be able to limit the possible positions on the metal complex for the organic partners. Toward this end, the synthesis of monometallic systems derived from M(CO)6 and two bidentate ligands, in which the number of possible coordination sites is reduced to two, has been investigated.
Octahedral metal carbonyls. 64. Ligand exchange in fac-(py)(diphos)Mo(CO)3 in toluene (T) solution (Py = pyridine; diphos = 1,2-bis(diphenylphosphino)ethane): The fac -[(T)(diphos)Mo(CO)3] intermediate
Asali, Khalil J.,Van Zyl, Gideon J.,Dobson, Gerard R.
, p. 3314 - 3319 (2008/10/08)
fac-(py)(diphos)Mo(CO)3 (1; py = pyridine; diphos = 1,2-bis(diphenylphosphino)ethane) reacts thermally with phosphines, phosphites, and triphenylstibine (=L) in toluene to afford fac-(L)(diphos)Mo(CO)3 products (2). The observed rate law suggests that the mechanism involves dissociation of py from 1 and competitive reaction of the resulting steady-state intermediate, fac-[(diphos)Mo(CO)3] (3), with py (reversibly) and with L (irreversibly). Pulsed laser flash photolysis of (diphos)Mo(CO)4 also affords 3, identified through comparisons of its reactivities with L to those observed for 3 produced thermally. Evidence suggests, however, that a predominant reaction species formed after pulsed laser flash photolysis of (diphos) Mo(CO)4 is fac-[(T)(diphos)Mo(CO)3] (4b) (T = toluene), in which toluene occupies a site in the octahedral coordination sphere of Mo and probably interacts with Mo via an agostic hydrogen; reversible dissociation of toluene from 4b affords 3. Rate data after flash photolysis also support the formation of [(η1-diphos)Mo(CO)4] and cis-[(T)(η1-diphos)Mo(CO)4] (5). The latter undergoes irreversible chelate ring closure with concerted expulsion of toluene to afford (diphos)Mo(CO)4. Rate constants and activation parameters for various reaction steps are presented and are discussed in terms of the steric and electronic properties of L.
