dr inż. Mariusz Michalczyk
Tel: (71)3203909
pokój 2.18A / budynek A3
Moje badania dotyczą chemii teoretycznej i obliczeniowej. Zajmuję się badaniem oddziaływań niekowalencyjnych w kompleksach molekularnych.
Ostatnie publikacje (2024):
Michalczyk, M., et al. (2024). "Attraction versus Repulsion between Methyl and Related Groups: (CH(3)NHCH(3))(2) and (CH(3)SeBr(2)CH(3))(2)." Chemphyschem 25(22): e202400495.
The starting point for this work was a set of crystal structures containing the motif of interaction between methyl groups in homodimers. Two structures were selected for which QTAIM, NCI and NBO analyses suggested an attractive interaction. However, the calculated interaction energy was negative for only one of these systems. The ability of methyl groups to interact with one another is then examined by DFT calculations. A series of (CH(3)PnHCH(3))(2) homodimers were allowed to interact with each other for a range of Pn atoms N, P, As, and Sb. Interaction energies of these C⋅⋅⋅C tetrel-bonded species were below 1 kcal/mol, but could be raised to nearly 3 kcal/mol if the C atom was changed to a heavier tetrel. A strengthening of the C⋅⋅⋅C intermethyl bonds can also be achieved by introducing an asymmetry via an electron-withdrawing substituent on one unit and a donor on the other. The attractions between the methyl and related groups occur in spite of a coulombic repulsion between sigma-holes on the two groups. NBO, AIM, and NCI tools must be interpreted with caution as they can falsely suggest bonding when the potentials are repulsive.
Michalczyk, M., et al. (2024). "Wolfium bonds in homodimers of MX(4)Y (M = Mo, W; X = F, Cl, Br; Y = O, S, Se)." Phys Chem Chem Phys 26(7): 5836-5847.
The term "wolfium bond" has been recently introduced to describe the noncovalent attraction between an atom of group 6 and a nucleophile via a sigma-hole binding site. Crystal structures commonly contain a motif wherein two MX(4)Y units are arranged in close proximity, where M represents either Mo or W, and X and Y refer to halogen and chalcogen atoms respectively. DFT calculations were thus applied to a wide range of homodimers of these molecules so as to assess their preferred arrangements, and to characterize the types of bonding that are present in each in a systematic manner. The most stable Dual-X configuration is symmetric and contains a pair of equivalent Mcdots, three dots, centeredX bonds. The interaction energies range from -8 to -29 kcal mol(-1), and are largest for X = F, Y = O, and M = W. The X electron donor is replaced by Y, and the two wolfium bonds are reduced to one, in the less stable Mono-Y structure, with interaction energies between -2 and -10 kcal mol(-1). There is some question as to whether the weaker bonds of this type constitute true wolfium bonds.