Non-covalent Interactions in Selected
Transition Metal Complexes
Filip Sagan and Mariusz P. Mitoraj
Abstract Chemical bonding in transition metal complexes is typically described
by Dewar–Chatt–Duncanson model which separates donation (ligand → metal)
and back-donation (metal → ligand) charge transfer processes—these are with no
doubt crucial factors which determine a number of properties of metal complexes.
This contribution highlights the importance of various non-covalent interactions
including untypical homopolar dihydrogen contacts C–H•••H–C in metal complexes.
The selected systems are: (1) Zn(II) species containing NTA (nitrotriacetic acid),
NTPA (nitrotri-3-propanoic), BPy (2,2
-bipyridyl) ligands, (2) cis-NiL 2 –hexane
(L–thiourea-based ligand) complex, and (3) hydrogen storage materials LiNMe 2 BH 3
and KNMe 2 BH 3 . It is shown consistently by various methods and bonding descriptors
including for example the charge and energy decomposition scheme ETS-NOCV,
Interacting Quantum Atoms (IQA), Reduced Density Gradient (NCI), Quantum Theory of Atoms in Molecules (QTAIM) and NMR spin-spin
1 J(C–H) coupling constants, that London dispersion dominated C–H•••H–C interactions and other more
typical hydrogen bonds (e.g. C–H•••N, C–H•••O) driven mostly by electrostatics,
are crucial for determination of the structures and stability of the selected metal
complexes. Although London dispersion forces are the fundamental factor (~70% of
the overall stabilization) contributing to C–H•••H–C interactions, the charge delocalization (outflow of electrons from the σ(C–H) bonds engaged in C–H•••H–C and
the accumulation in the interatomic H•••H region) as well as electrostatic terms are
also non-negligible (~30%). Remarkably, hydride–hydride interactions B–H•••H–B
in LiNMe 2 BH 3 are found to be repulsive due to dominant destabilizing electrostatic
contribution as opposed to stabilizing C–H•••H–C.
F. Sagan · M. P. Mitoraj (B)
Department of Theoretical Chemistry, Faculty of Chemistry, Jagiellonian University,
Gronostajowa 2, 30-387 Kraków, Poland
e-mail: mitoraj@chemia.uj.edu.pl
F. Sagan
e-mail: filip.sagan@doctoral.uj.edu.pl
© Springer Nature Switzerland AG 2019
E. Broclawik et al. (eds.), Transition Metals in Coordination Environments,
Challenges and Advances in Computational Chemistry and Physics 29,
https://doi.org/10.1007/978-3-030-11714-6_3
65
Transition Metal Complexes
Filip Sagan and Mariusz P. Mitoraj
Abstract Chemical bonding in transition metal complexes is typically described
by Dewar–Chatt–Duncanson model which separates donation (ligand → metal)
and back-donation (metal → ligand) charge transfer processes—these are with no
doubt crucial factors which determine a number of properties of metal complexes.
This contribution highlights the importance of various non-covalent interactions
including untypical homopolar dihydrogen contacts C–H•••H–C in metal complexes.
The selected systems are: (1) Zn(II) species containing NTA (nitrotriacetic acid),
NTPA (nitrotri-3-propanoic), BPy (2,2
-bipyridyl) ligands, (2) cis-NiL 2 –hexane
(L–thiourea-based ligand) complex, and (3) hydrogen storage materials LiNMe 2 BH 3
and KNMe 2 BH 3 . It is shown consistently by various methods and bonding descriptors
including for example the charge and energy decomposition scheme ETS-NOCV,
Interacting Quantum Atoms (IQA), Reduced Density Gradient (NCI), Quantum Theory of Atoms in Molecules (QTAIM) and NMR spin-spin
1 J(C–H) coupling constants, that London dispersion dominated C–H•••H–C interactions and other more
typical hydrogen bonds (e.g. C–H•••N, C–H•••O) driven mostly by electrostatics,
are crucial for determination of the structures and stability of the selected metal
complexes. Although London dispersion forces are the fundamental factor (~70% of
the overall stabilization) contributing to C–H•••H–C interactions, the charge delocalization (outflow of electrons from the σ(C–H) bonds engaged in C–H•••H–C and
the accumulation in the interatomic H•••H region) as well as electrostatic terms are
also non-negligible (~30%). Remarkably, hydride–hydride interactions B–H•••H–B
in LiNMe 2 BH 3 are found to be repulsive due to dominant destabilizing electrostatic
contribution as opposed to stabilizing C–H•••H–C.
F. Sagan · M. P. Mitoraj (B)
Department of Theoretical Chemistry, Faculty of Chemistry, Jagiellonian University,
Gronostajowa 2, 30-387 Kraków, Poland
e-mail: mitoraj@chemia.uj.edu.pl
F. Sagan
e-mail: filip.sagan@doctoral.uj.edu.pl
© Springer Nature Switzerland AG 2019
E. Broclawik et al. (eds.), Transition Metals in Coordination Environments,
Challenges and Advances in Computational Chemistry and Physics 29,
https://doi.org/10.1007/978-3-030-11714-6_3
65