16632-87-4

Upstream product

• 1662-01-7 bathophenanthroline 
• 199620-14-9 chromium⁽⁰⁾ hexacarbonyl 

Downstream Products

• 22289-73-2 (CO)3Cr(4.7-diphenyl-phenanthroline-(1.10))(P(OC₆H₅)3) 

Relevant academic research and scientific papers

Kinetic studies of group VI metal carbonyl complexes. IV. Substitution reactions of o-phenanthroline complexes of chromium hexacarbonyl

Cr(CO)4(X-o-phen) reacts with P(OCH2)3CCH3, L, at a rate which is independent of the concentration of L to form cis-Cr(CO)3(L)(X-o-phen) as the only reaction product. The rate of reaction of Cr(CO)4(X-o-phen) is however dependent on the basicity of the X-o-phen chelate in a manner which is predictable from a linear free energy expression. The reaction rate dependence on the pKa of X-o-phen is contrary to what would be predicted from current π-bonding theories since the reaction rate was found to increase with increasing pKa of the chelate. The C-O stretching frequencies of the Cr(CO)4-(X-o-phen) complexes decrease with increasing basicity of X-o-phen. This would be predicted from π-bonding theory but does not explain the observed rate trend. The increases in reaction rates with increasing chelate pKa are discussed in terms of a stabilized transition state and in ternis of labilizing and nonlabilizing ligands.

Photolysis of group 6 metal hexacarbonyl solutions containing diimine ligands. Spectral characterization and reaction kinetics of a photoproduced intermediate, monodentate M(CO)5(diimine)

Electronic absorption spectra have been obtained immediately following the photolysis of M(CO)6 solutions containing diimine ligands (1,10-phenanthroline, 2,2′-bipyridine, 1,4-diazabutadiene, or their derivatives) with the use of a microprocessor-controlled diode-array UV-visible spectrophotometer. The time-dependent spectra illustrate rapid formation of a reaction intermediate that is assigned to be M(CO)5L, where L is a diimine ligand coordinated in a monodentate fashion. Monodentate M(CO)5L subsequently extrudes CO thermally via a first-order kinetic process to form stable M(CO)4L. No discernable M(CO)5L intermediates were observed when L = 1,10-phenanthroline (phen) or a phen derivative consistent with the rigid coplanar nature of these ligands. In contrast, the chelation of M(CO)5L complexes, where L = 2,2′-bipyridine, 1,4-diazabutadiene, or derivatives, proceeds with considerably slower reaction rates. The rate data are interpreted in terms of the stereochemistry of the monodentate intermediate. For a given ligand, the reaction rate decreases in the sequence Mo > Cr > W, analogous to the order of CO release in M(CO)6; this ordering suggests that the predominant barrier to chelation involves breaking of the M-C bond. Derived activation energy parameters indicate that the chelation reaction is enthalpy-controlled. The marked dependence of reaction rate on diimine and resulting negative activation entropy values imply that the chelation mechanism proceeds with a substantial associative component.