Bonding in Cationic MCH₂⁺ (M=K–La, Hf–Rn): A Theoretical Study on Periodic Trends

Abstract

DFT and CCSD(T) calculations have been performed to investigate the bonding situation of 54 cationic methylene complexes, MCH(2)(+) (M=K-La, Hf-Rn). A comparison of the computed results with experimentally and CBS-QB3-derived data demonstrates the reliability of B3LYP/def2-QZVP with regard to the bond dissociation energies. Further, the bonding character of the MCH(2)(+) complexes is revealed by geometrical and molecular-orbital (MO) analysis. The comparison of the periodic trends within the s-, p-, and d-block MCH(2)(+) carbenes shows a pattern different for main-group versus transition-metal complexes. By combining this work with the recently reported trends for the f-block lanthanide carbenes MCH(2)(+), a systematic and comprehensive overview can be obtained.

Theoretical Investigation of Linker Effects on New Designed Bodipy-Ferrocene Based Three Channels Calcium (II) Ion Sensors; as Redox, Colorimetric and Fluorescent Properties

“…LANL2DZ basis set was applied. This basis set was found to be in good agreement with the experimental results in describing metal-carbon bonds for organometallic compounds in many cases [10].…”

The “Missing Link”: The Gas‐Phase Generation of Platinum–Methylidyne Clusters PtnCH+ (n=1, 2) and Their Reactions with Hydrocarbons and Ammonia

“…Finally, in the ion-molecule reactions with ammonia, both platinum complexes give rise to proton transfer to produce NH 4 + ; however, only the encounter complex generated with PtCH + undergoes efficient dehydrogenation of the substrate, and the rather minor formation of CNH 4 mal dehydrogenation of methane at ambient conditions. [10] Also platinum-cluster cations react with CH 4 according to Equation (1) to form the corresponding carbene complexes Pt n CH 2 + (n = 2-9). [11] Collision-induced dissociation (CID) of Pt n CH 2 + gives rise to further dehydrogenation concomitant with the formation of the carbide complexes Pt n C + for n > 2; the latter species can also be selectively produced by the reactions of kinetically excited Pt n + clusters with methane [Eq.…”

“…[31] Obviously, the sequence that commences with the evaporation of CO 2 , 6 ¾fi 10 ¾fi 11 ¾fi 12 a, is clearly favored both thermochemically and kinetically over the alternative, 6 ¾fi 14 ¾fi 7. [32] In addition, because TSA C H T U N G T R E N N U N G (12b-13), which is responsible for the reductive elimination of CH 2 COO from 12 b, is located below TSA C H T U N G T R E N N U N G (10)(11), based on the DFT calculations, intermediates, for example 12, are not expected to be observed upon CID of 6, which is in line with the experimental findings. In contrast, when CH 2 COO is lost first, CO 2 elimination from 7 must proceed through the high energy TSA C H T U N G T R E N N U N G (15)(16), which is located 117 kJ mol À1 above 7; therefore, 7 is detected experimentally.…”

“…The corresponding transition state, TSA C H T U N G T R E N N U N G (8-17), is located 189 kJ mol À1 above 8, and, for the release of CH 3 COOH from 17 to produce 18, yet another 185 kJ mol À1 are necessary. After the isomerization 18 ¾fi 9, a further hydrogen atom is abstracted from the remaining CH 2 unit through TSA C H T U N G T R E N N U N G (9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19), and 2 is produced www.chemeurj.org upon liberation of CH 3 COOH. The step 9 ¾fi 19 is ratelimiting in the overall sequence of events.…”

Methylidenkomplexe der Seltenerdmetalle

“…[30] Kurz darauf erweiterten Schwarz und Mitarbeiter diese Studien für die gesamte Reihe der MCH 2 + -Kationen (M = K-La und Hf-Rn), um periodische Trends zu identifizieren. [31] Pyykkç et al berechneten, dass prinzipiell alle Lanthanoide Doppelbindungen zur Methylengruppe ausbilden kçnnen. Die Doppelbindung wird dabei hauptsächlich durch die 5d-Orbitale mit nur einer geringen Beteiligung der 6s-Orbitale ausgebildet.…”