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Articles you may be interested inVibrational energy relaxation of diatomic molecules isolated in raregas matrices: Role of orientational motions J. Chem. Phys. 68, 4056 (1978); 10.1063/1.436307 ESR of the triplet molecules CCO and CNN in raregas matrices; isotope and matrix effects J. Chem. Phys. 62, 4592 (1975); 10.1063/1.430432Nonradiative vibrational relaxation of diatomic molecules isolated in solid rare-gas matrices Mn, and Mn, have been isolated in argon, krypton, and xenon matrices and their X -band ESR spectra observed at 4 and up to 70 K, depending upon the matrix. As predicted by Nesbet, the lowest state of Mn, is I.I, and the two atoms are exchange coupled (antiferromagnetically). The temperature behavior of the ESR bands in the higher spin states (S = 1,2,3) was approximately in accord with a Lande interval rule, and a value of J = -9 ± 3 em -I was obtained from the S = 2 intensity variations. Each fine structure line appears with a superimposed II-line hyperfine pattern with splitting one-half that of isolated HMn atoms (30 G). The anisotropic exchange interactions fit the Judd-Owen relationship with D, = -0.043(2) and D. = -0.001(4) em-I. Assuming D, arises solely from magnetic dipole interaction, the interatomic distance in Mn, is calculated to be 3.4 A. Mn, appears in more concentrated matrices as a highly oriented axial molecule with its axis perpendicular to the flat sapphire substrate surface. The observed fine structure indicates that the molecule contains 25 unpaired electrons (S = 25/2) and has magnetic parametersg, = 1.997(1), gil = 1.979(2), D = -0.013(1) em-I. All HMn hyperfine structure lies within the Iinewidths and is therefore unresolved. It was concluded that the molecule most probably contains five Mn atoms and is a plane pentagon. With this model an attempt was made to rationalize the observed g shifts.190

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The Mn2 molecule, exhibiting antiferromagnetic exchange coupling between the 3d 5 electrons on each atom, has been investigated further in cyclopropane matrices at temperatures ranging from 12 to 110 K. This allowed electron-spin-resonance spectra to be observed in the higher spin states S = 4 and 5 and confirmed the previous deduction of van der Waals bonding with r~3.4 A. In addition, the derived anisotropic parameters Ds suggest that exchange striction (as previously observed in solids) is occurring such that r varies from about 3.2 to 3.6 A in the S = 0 to S = 5 states, with a corresponding variation in the exchange coupling constant J in these states. The removal of one electron to produce Mn 2 + results in the formation of a single abond and high-spin coupling among the remaining 11 unpaired electrons to yield a 12l: ground state. In contrast, its isoelectronic counterpart CrMn is found to have a 4l: ground state and multiple bonding, more in accord with expectations for a diatomic between Cr 2 and Mn 2 .