d–d Dative Bonding Between Iron and the Alkaline‐Earth Metals Calcium, Strontium, and Barium

Stegner, Philipp; Färber, Christian; Oetzel, Jan; Siemeling, Ulrich; Wiesinger, Michael; Langer, Jens; Pan, Sudip; Holzmann, Nicole; Frenking, Gernot; Albold, Uta; Sarkar, Biprajit; Harder, Sjoerd

doi:10.1002/anie.202005774

Cited by 33 publications

(18 citation statements)

References 48 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In these complexes, the metal–ligand bonding is contributed mainly by the metal ( n – 1)d AOs. Calculations also suggest that the d orbitals participate in bonding in divalent species. − In particular, we found that calcium is able to form heteronuclear carbonyl cation complexes with transition metals featuring a weak Fe → Ca d–d dative bond…”

Section: Heteronuclear Calcium–iron Carbonyl Cation Complexes With D–...mentioning

confidence: 82%

Transition-Metal Chemistry of the Heavier Alkaline Earth Atoms Ca, Sr, and Ba

Zhou

Frenking

2021

Acc. Chem. Res.

Self Cite

View full text Add to dashboard Cite

Conspectus Alkaline earth elements beryllium, magnesium, calcium, strontium, and barium with an ns2 valence-shell configuration are usually classified as main-group elements that belong to the s-block atoms. For a long time, the elements were considered to be rather chemically uninteresting atomic species due to preconceived ideas about bonding, structure, and reactivity. They typically use the two ns valence electrons in forming ionic salt compounds with the metal in a formal oxidation state of +2. For the heavier alkaline earth atoms, calcium, strontium, and barium, their (n – 1)d atomic orbitals (AOs) are empty but lie close in energy to the valence np orbitals. Earlier theoretical investigations have already suggested that these elements can employ the (n – 1)d AOs to some extent to form polar bonds in divalent species in which the alkaline earth metal centers are sufficiently positively charged. The d orbital involvement increases from Ca to Sr and markedly in Ba. Thus, barium has been termed an honorary transition metal. Recently, molecular complexes of Ca, Sr, and Ba were prepared in the gas phase and in a low-temperature solid neon matrix and were detected by infrared spectroscopy. An analysis of the electronic structures of [Ba(CO)]+, [Ba(CO)]−, saturated coordinated octacarbonyls [M(CO)8] and [M(CO)8]+, isoelectronic dinitrogen complexes [M(N2)8] and [M(N2)8]+, and the tribenzene complexes [M(Bz)3] (M = Ca, Sr, Ba) revealed that the metal–ligand bonding can be straightforwardly discussed using the traditional Dewar–Chatt–Duncanson (DCD) model as in classical transition-metal complexes. The metal–ligand bonds can be explained with metal → ligand π back donation from occupied metal (n – 1)d AOs to vacant antibonding π molecular orbitals of the ligands with concomitant σ donation from occupied MOs of the ligands to vacant metal d orbitals of the alkaline earth atoms. In addition, heteronuclear Ca–Fe carbonyl cation complexes were also produced in the gas phase. Bonding analysis of the coordination saturated [CaFe(CO)10]+ complex implies that it can be described by the bonding interactions between a [Ca(CO)6]2+ fragment and an [Fe(CO)4]− anion fragment in forming a Fe → Ca d–d dative bond. The nature of metal–ligand and metal–metal bonding was quantitatively elucidated by the energy decomposition analysis in conjunction with the natural orbitals for the chemical valence (EDA-NOCV) method, which indicate that the (n – 1)d AOs of the alkaline earth metals are the dominant orbitals participating in the covalent interactions, just as typical transition metals. The results indicate that the heavier alkaline earth elements have a much richer covalent chemistry than previously thought. These findings, along with earlier studies, suggest that the heavier alkaline earth atoms Ca, Sr, and Ba should be classified as transition metals rather than main group atoms in the periodic table of the elements. This interesting structural chemistry, together with some recently reported examples of spectacular reacti...

show abstract

Section: Heteronuclear Calcium–iron Carbonyl Cation Complexes With D–...mentioning

confidence: 82%

Transition-Metal Chemistry of the Heavier Alkaline Earth Atoms Ca, Sr, and Ba

Zhou

Frenking

2021

Acc. Chem. Res.

Self Cite

View full text Add to dashboard Cite

show abstract

“…The strongest bonds to calcium should be covalent Ca–N bonds, which are shortened due to partial donation of the lone pairs at the nitrogen atoms to empty d orbitals of calcium. The accessibility of these orbitals in heavy alkaline earth metals has recently been demonstrated in a detailed study . The Ca–O bonds are slightly longer than typical covalent single bonds, which reflects the dative nature of this bond.…”

Section: Introductionmentioning

confidence: 84%

“…The accessibility of these orbitals in heavy alkaline earth metals has recently been demonstrated in a detailed study. 15 The Ca−O bonds are slightly longer than typical covalent single bonds, which reflects the dative nature of this bond. The short PC bonds are a hint that there might be a partial π-donation of these bonds into the d orbitals of calcium.…”

Section: ■ Introductionmentioning

confidence: 99%

Di-ortho-beryllated Carbodiphosphorane: A Compound with a Metal–Carbon Double Bond to an Element of the s-Block

et al. 2020

Self Cite

View full text Add to dashboard Cite

Double bonds have been realized for a wide variety of elements in the p-, d-, and f-blocks. However, no s-block metal complexes with a double bond have been identified. Here we report the synthesis and characterization of a di-ortho-beryllated carbodiphosphorane, which exhibits a double dative BeC bond. This species shows an unprecedented bonding situation at the metal center, which was extensively analyzed by experimental and computational means.

show abstract

“…The geometrical optimisations followed by harmonic vibrational frequency computations of the molecules were performed at the BP86 [26] /def2‐TZVPP [27] level of theory. The BP86 functional was chosen for this project because it gave the best agreement for the geometries of the calculated molecules with experimental values and previous high‐level calculations, and it proved to be very accurate in another project in which we calculated the geometries of heavy alkaline‐earth compounds [28] . This basis set uses quasi‐relativistic effective core potentials for 28 and 46 core electrons for Sr and Ba, respectively, and all‐electron basis sets for the other atoms.…”

Section: Theoretical Methodsmentioning

confidence: 99%

The Valence Orbitals of the Alkaline‐Earth Atoms

Fernández

Holzmann

Frenking

2020

Chemistry A European J

Self Cite

View full text Add to dashboard Cite

Quantum chemical calculations of the alkaline‐earth oxides, imides and dihydrides of the alkaline‐earth atoms (Ae=Be, Mg, Ca, Sr, Ba) and the calcium cluster Ca6H9[N(SiMe3)2]3(pmdta)3 (pmdta=N,N,N′,N′′,N′′‐pentamethyldiethylenetriamine) have been carried out by using density functional theory. Analysis of the electronic structures by charge and energy partitioning methods suggests that the valence orbitals of the lighter atoms Be and Mg are the (n)s and (n)p orbitals. In contrast, the valence orbitals of the heavier atoms Ca, Sr and Ba comprise the (n)s and (n−1)d orbitals. The alkaline‐earth metals Be and Mg build covalent bonds like typical main‐group elements, whereas Ca, Sr and Ba covalently bind like transition metals. The results not only shed new light on the covalent bonds of the heavier alkaline‐earth metals, but are also very important for understanding and designing experimental studies.

show abstract

d–d Dative Bonding Between Iron and the Alkaline‐Earth Metals Calcium, Strontium, and Barium

Cited by 33 publications

References 48 publications

Transition-Metal Chemistry of the Heavier Alkaline Earth Atoms Ca, Sr, and Ba

Transition-Metal Chemistry of the Heavier Alkaline Earth Atoms Ca, Sr, and Ba

Di-ortho-beryllated Carbodiphosphorane: A Compound with a Metal–Carbon Double Bond to an Element of the s-Block

The Valence Orbitals of the Alkaline‐Earth Atoms

Contact Info

Product

Resources

About