A new method for estimating the degree of fragmentation of metallocomplexes under electron impact with cleavage of the metal--ligand bond was suggested, The method is based on mass spectrometric data. Using a representative selection of 67 organometallic compounds of different classes such as metal carbonyls, metallocenes, and eymantrene and bensenr derivatives, a correlation between the degree of fragmentation and the dissociation energy of metal--ligand bonds was developed. The correlation is evidence that the parameter can be used for quantitative estimation of the reactivity of metallocomplexes in the gas phase.Key words: metallocomplexes, mass spectrometry, degree of fragmentation, bond energy.The elimination of ligands is the main direction of fragmentation of the majority of metallocomplexes of the LM(CO), type under electron impact action. The intensities of the LM(CO)x + and M(CO)x + ions (x = 0--n) that formed are determined by the dissociation energies of the corresponding bonds, t Therefore, mass spectra are often used to estimate the relative stability of metal--ligand bonds. Several methods of estimation are known. (NMe3)] complexes with different transition metals (M = Cr, Me, and W) and elements (E = P, As, Sb, and Bi). 3.4 For the CpMn(X)(Y)(Z) complexes, a correlation between the total intensity of peaks of ions containing the CpMn, XMn, YMn, or ZMn fragments and dissociation energies of the corresponding bonds has been established, s.~ All the correlations indicated above are appropriate for the qualitative or, in the best case, semiquantitative estimation of tendencies in the change in metal--ligand bond stability for a narrow ,'ange of related compounds and cannot be used for comparison of complexes of different classes. 7,8 In this work, we describe a general method for the calculation of the degree of fragmentation of different metallocomplexes fragmented under the electron impact action with cleavage of the metal--ligaud bond.The scheme of fragmentation of the LM(CO) 2 complex is presented below (Scheme 1).
Scheme 1where at--a 4 is the fraction of ions fragmented with the elimination of the CO group; b|--b 4 is the fraction of ions fragmented with the elimination of the L ligand; and c is the fraction of LM ions fragmented with the elimination of the X fragment.According to this scheme, we can write the following system of equations for the intensities of ion peaks normalized to the total ionic current: Hence the following expressions can be written for tile total fractions of the eliminated carbonyl groups and ligand L