scholarly journals Charge control of the inverse trans-influence

2015 ◽  
Vol 51 (93) ◽  
pp. 16671-16674 ◽  
Author(s):  
Henry S. La Pierre ◽  
Michael Rosenzweig ◽  
Boris Kosog ◽  
Christina Hauser ◽  
Frank W. Heinemann ◽  
...  
Keyword(s):  
Ground State ◽  
Charge Control ◽  
Charge Localization ◽  
Multiple Bonding ◽  
Trans Influence ◽  
Multiply Bonded ◽  
Metal Ligand

The relative charge localization on the multiply bonded ligand (O2− or TMSN2−) governs the ground state stabilization derived from the inverse trans-influence (ITI) in U(vi) complexes of the [((RArO)3tacn)UL]+ system with metal-ligand multiple bonding (MLMB).

Effects of a scattering center on the ground-state energy of quantum-dot lithium

2017 ◽  
Vol 31 (07) ◽  
pp. 1750071
Author(s):  
Z. D. Vatansever ◽  
S. Sakiroglu ◽  
I. Sokmen
Keyword(s):  
Quantum Dot ◽  
Ground State Energy ◽  
Ground State ◽  
State Energy ◽  
Electronic Charge ◽  
Strongly Correlated ◽  
Configuration Interaction Method ◽  
Charge Localization ◽  
Scattering Center ◽  
Spin Properties

In this paper, the effects of a repulsive scattering center on the ground-state energy and spin properties of a three-electron parabolic quantum dot are investigated theoretically by means of configuration interaction method. Phase transition from a weakly correlated regime to a strongly correlated regime is examined from several strengths and positions of Gaussian impurity. Numerical results reveal that the transition from spin-1/2 to spin-3/2 state depends strongly on the location of the impurity which accordingly states the controllability of the spin polarization. Moreover, broken circular symmetry results in more pronounced electronic charge localization.

Study of metal-ligand multiple bonding in osmium and iridium imido complexes: evidence for the cyclopentadienyl-imido analogy

1992 ◽  
Vol 11 (12) ◽  
pp. 4221-4225 ◽  
Author(s):  
David S. Glueck ◽  
Jennifer C. Green ◽  
Richard I. Michelman ◽  
Ian N. Wright
Keyword(s):  
Multiple Bonding ◽  
Imido Complexes ◽  
Metal Ligand

Metal–ligand multiple bonding in uranium: structure and reactivity

2010 ◽  
Vol 39 (5) ◽  
pp. 1145-1158 ◽  
Author(s):  
Trevor W. Hayton
Keyword(s):  
Multiple Bonding ◽  
Metal Ligand

scholarly journals Design, Isolation, and Spectroscopic Analysis of a Tetravalent Terbium Complex

2019 ◽  
Author(s):  
Natalie Rice ◽  
Ivan Popov ◽  
Dominic Russo ◽  
John Bacsa ◽  
Enrique Batista ◽  
...  
Keyword(s):  
Ground State ◽  
Molecular Complexes ◽  
Lanthanide Ions ◽  
Ligand Field ◽  
Zero Field ◽  
High Symmetry ◽  
Zero Field Splitting ◽  
Terbium Complex ◽  
Field Splitting ◽  
Metal Ligand

Synthetic strategies to yield molecular complexes of high-valent lanthanides, other than the ubiquitous Ce<sup>4+</sup> ion, are exceptionally rare, and thorough, detailed characterization in these systems is limited by complex lifetime and reaction and isolation conditions. The synthesis of high-symmetry complexes in high purity with significant lifetimes in solution and solid-state are essential for determining the role of ligand-field splitting, multiconfigurational behavior, and covalency in governing the reactivity and physical properties of these potentially technologically transformative tetravalent ions. We report the synthesis and physical characterization of an <i>S</i><sub>4</sub> symmetric, four-coordinate tetravalent terbium complex, [Tb(NP(1,2-bis-<i><sup>t</sup></i>Bu-diamidoethane)(NEt<sub>2</sub>))<sub>4</sub>] (where Et is ethyl and <i>t</i>Bu is <i>tert</i>-butyl). The ligand field in this complex is weak and the metal-ligand bonds sufficiently covalent so that the tetravalent terbium ion is stable and accessible via a mild oxidant from the anionic, trivalent, terbium precursor, [(Et<sub>2</sub>O)K][Tb(NP(1,2-bis-<i><sup>t</sup></i>Bu-diamidoethane)(NEt<sub>2</sub>))<sub>4</sub>]. The significant stability of the tetravalent complex enables its thorough characterization. The step-wise development of the supporting ligand points to key ligand control elements for further extending the known tetravalent lanthanide ions in molecular complexes. Magnetic susceptibility, electron paramagnetic resonance (EPR) spectroscopy, X-ray absorption near-edge spectroscopy (XAS), and density functional theory studies indicate a <i>4f<sup>7</sup></i> ground state for [Tb(NP(1,2-bis-<i><sup>t</sup></i>Bu-diamidoethane)(NEt<sub>2</sub>))<sub>4</sub>] with considerable zero-field splitting: demonstrating that magnetic, tetravalent lanthanide ions engage in covalent metal-ligand bonds. This result has significant implications for the use of tetravalent lanthanide ions in magnetic applications since the observed zero-field splitting is intermediate between that observed for the trivalent lanthanides and for the transition metals. The similarity of the multiconfigurational behavior in the ground state of [Tb(NP(1,2-bis-<i><sup>t</sup></i>Bu-diamidoethane)(NEt<sub>2</sub>))<sub>4</sub>] (measured by Tb L<sub>3</sub>-edge XAS) to that observed in TbO<sub>2</sub> implicates ligand control of multiconfigurational behavior as a key component of the stability of the complex.

scholarly journals The inverse-trans-influence in tetravalent lanthanide and actinide bis(carbene) complexes

2017 ◽  
Vol 8 (1) ◽  
Author(s):  
Matthew Gregson ◽  
Erli Lu ◽  
David P. Mills ◽  
Floriana Tuna ◽  
Eric J. L. McInnes ◽  
...  
Keyword(s):  
Oxidation State ◽  
Theoretical Data ◽  
High Oxidation State ◽  
Carbene Complexes ◽  
Trans Influence ◽  
High Oxidation ◽  
High Valent ◽  
Tetravalent Cerium ◽  
Limited Scope ◽  
Metal Ligand

Abstract Across the periodic table the trans-influence operates, whereby tightly bonded ligands selectively lengthen mutually trans metal–ligand bonds. Conversely, in high oxidation state actinide complexes the inverse-trans-influence operates, where normally cis strongly donating ligands instead reside trans and actually reinforce each other. However, because the inverse-trans-influence is restricted to high-valent actinyls and a few uranium(V/VI) complexes, it has had limited scope in an area with few unifying rules. Here we report tetravalent cerium, uranium and thorium bis(carbene) complexes with trans C=M=C cores where experimental and theoretical data suggest the presence of an inverse-trans-influence. Studies of hypothetical praseodymium(IV) and terbium(IV) analogues suggest the inverse-trans-influence may extend to these ions but it also diminishes significantly as the 4f orbitals are populated. This work suggests that the inverse-trans-influence may occur beyond high oxidation state 5f metals and hence could encompass mid-range oxidation state actinides and lanthanides. Thus, the inverse-trans-influence might be a more general f-block principle.

Impact of Coordination Geometry, Bite Angle, and Trans Influence on Metal–Ligand Covalency in Phenyl-Substituted Phosphine Complexes of Ni and Pd

2015 ◽  
Vol 54 (12) ◽  
pp. 5646-5659 ◽  
Author(s):  
Courtney M. Donahue ◽  
Samuel P. McCollom ◽  
Chelsie M. Forrest ◽  
Anastasia V. Blake ◽  
Brian J. Bellott ◽  
...  
Keyword(s):  
Coordination Geometry ◽  
Phosphine Complexes ◽  
Bite Angle ◽  
Trans Influence ◽  
Metal Ligand

scholarly journals Seeing is Believing: Experimental Spin States from Machine Learning Model Structure Predictions

2020 ◽  
Author(s):  
Michael Taylor ◽  
Tzuhsiung Yang ◽  
Sean Lin ◽  
Aditya Nandy ◽  
Jon Paul Janet ◽  
...  
Keyword(s):  
Machine Learning ◽  
Electronic Structure ◽  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Ground State ◽  
Spin States ◽  
Machine Learning Model ◽  
Metal Ligand ◽  
Ligand Bond

<p>Determination of ground-state spins of open-shell transition metal complexes is critical to understanding catalytic and materials properties but also challenging with approximate electronic structure methods. As an alternative approach, we demonstrate how structure alone can be used to guide assignment of ground-state spin from experimentally determined crystal structures of transition metal complexes. We first identify the limits of distance-based heuristics from distributions of metal–ligand bond lengths of over 2,000 unique mononuclear Fe(II)/Fe(III) transition metal complexes. To overcome these limits, we employ artificial neural networks (ANNs) to predict spin-state-dependent metal–ligand bond lengths and classify experimental ground state spins based on agreement of experimental structures with the ANN predictions. Although the ANN is trained on hybrid density functional theory data, we exploit the method-insensitivity of geometric properties to enable assignment of ground states for the majority (ca. 80-90%) of structures. We demonstrate the utility of the ANN by data-mining the literature for spin-crossover (SCO) complexes, which have experimentally-observed temperature-dependent geometric structure changes, by correctly assigning almost all (> 95%) spin states in the 46 Fe(II) SCO complex set. This approach represents a promising complement to more conventional energy-based spin-state assignment from electronic structure theory at the low cost of a machine learning model. </p>

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