Heat of reaction of (norbornadiene) molybdenum tetracarbonyl with monodentate and bidentate ligands. Solution thermochemical study of ligand substitution in the complexes cis-L2Mo(CO)4 Article

Mukerjee, SL, Nolan, SP, Hoff, CD et al. (1988). Heat of reaction of (norbornadiene) molybdenum tetracarbonyl with monodentate and bidentate ligands. Solution thermochemical study of ligand substitution in the complexes cis-L2Mo(CO)4 . INORGANIC CHEMISTRY, 27(1), 81-85. 10.1021/ic00274a018

cited authors

  • Mukerjee, SL; Nolan, SP; Hoff, CD; Lopez de la Vega, R

authors

abstract

  • The enthalpy of reaction of (NBD)Mo(CO)4 (NBD = norbornadiene) with a number of monodentate and bidentate ligands forming cis-L2Mo(CO)4 has been measured at 30 °C in THF solution. The heats of reaction span a range of 33 kcal/mol. The order of stability for monodentate ligands is PC133 < As(C6H5)3 < py < P(C6H5)3 < AsEt3 < P(OC6H5)3 < P(C6H5)2(CH3) < CO < P(C6H5)(CH3) < P(OCH3)3 < P(n-Bu)3 < (C6H11 n)NC < PEt3 < PMe3. The series of chelating bidentate phosphines R2P- (CH2)nPR2 ( = 1-4, R = C6H5; = 1, 2, R = CH3) and several related ligands were investigated. The chelating ring systems in the metallacycles show strain energies of about 8 kcal/mol for four-membered rings. The mixed ligand (C6H5)2PCH2CH2- As(C6H5)2 shows a heat of binding midway between the heats of binding of (C6H5)2PCH2CH2(C6H5)2 and (C6H5)2AsCH2CH2As( C6H5)2, implying group additivity in this system. The complex (phen)Mo(CO)4 is some 5 kcal/mol more stable than (bpy)Mo(CO)4, presumably due to conformational effects in the free ligand. The ligand 1,5-cyclooctadiene forms a complex 2 kcal/mol less stable than that of norbornadiene. The influences of steric and electronic factors in determining the Mo-L bond strength are discussed. © 1988, American Chemical Society. All rights reserved.

publication date

  • January 1, 1988

published in

Digital Object Identifier (DOI)

start page

  • 81

end page

  • 85

volume

  • 27

issue

  • 1