Electronic and geometric structure analysis of neutral and anionic metal nitric chalcogens: The case of MNX series (M=Li, Na, Be and X=O, S, Se, Te)

Abstract

Coupled cluster and multireference configuration approaches are employed to study the electronic and geometric structures of mono‐coordinated complexes of lithium, sodium, and beryllium with nitric oxide and its isovalent NS, NSe, and NTe species. Ground and low‐lying excited states were examined for both linear‐bonded and side‐bonded isomers. We show that the ionic M+NX− (M=Li, Na, Be and X=O, S, Se, Te) picture is a more natural representation and can account for the symmetry of the low−lying electronic states as Σ−, Δ, and Σ+, the smaller excitation energies and the larger binding energies for heavier X. An additional electron binds to the positively charged Li and Na terminal creating stable anions. The electron affinity (EA) of LiNX and NaNX species is in the 0.5–0.8 eV range. Despite the negative EA of beryllium and the very small EA of NO, the BeNO molecule has an EA of ~1.0 eV, which is increased to ~1.5 eV for the heavier BeNX species. This is attributed to the fact that the additional electron goes to the beryllium end for BeNO but to a π(MN)π*(NX) orbital of the rest species. Our accurate results contradict previous findings and serve as a guide for future experimental studies. © 2019 Wiley Periodicals, Inc.

Ground and excited electronic structures of electride and alkalide units: The cases of Metal‐Tren, ‐Azacryptand, and ‐TriPip222 complexes

“…Generally, as we move down of the periodic table the D e s of alkali metal–complexes decrease 23,54,55 . This is in line with all the studied systems in this work except for Na(Azacrypt) which has a 4.47 kcal/mol lower D e compared to K(Azacrypt) (Table 1).…”

“…Generally, as we move down of the periodic table the D e s of alkali metal-complexes decrease. 23,54,55 (Azacrypt) 0,+ whereas the opposite is true for K(Tripip) 0,+ versus K (Azacrypt) 0,+ . In all cases, the cationic complexes carry larger D e s compared to the neutral complexes owing to the stronger electrostatic attraction between M + and electron-rich ligands.…”

Superatomic Chelates: The Cases of Metal Aza-Crown Ethers and Cryptands

“…For instance, the D e s of Li(NH 3 ) 4 vs Na(NH 3 ) 4 , Li(CO) 3 vs Na(CO) 3 , and LiNO vs NaNO are 57 vs 32, 23 vs −6.3, and 33 vs 15 kcal/mol, respectively. 25,46,47 The strong electrostatic interactions between metal cations vs coordination sites account for the larger D e s of cationic species. In overall, the D e s of M( [9]aneN 3 ) 2 are larger than M [18]aneN 6 for all M.…”

Be–Be Bond in Action: Lessons from the Beryllium–Ammonia Complexes [Be(NH3)0–4]20,2+

“…Beryllium is in its 3 P state as well in BeCO, which is however metastable dissociating to Be­( 1 S; 1s 2 2s 2 ) + CO. On the other hand, Be­(CO) 2 is stable with respect to Be + 2CO, and the beryllium center is in an even higher in situ electronic state, 2 3 P (1s 2 2p 2 ) at 59696 cm –1 . The stabilization of 2 3 P is due to the “simultaneous” OC → Be ← CO dative bonds formation and π-back-donation of the two 2p π electrons of Be to π*­(CO). , Finally, high electron affinity ligands, such as O 2 or NO, oxidize beryllium to Be + or Be 2+ ; see for example Be­(O 2 ) 1–2 and Be­(NO) compounds. , …”

“…17,18 Finally, high electron affinity ligands, such as O 2 or NO, oxidize beryllium to Be + or Be 2+ ; see for example Be(O 2 ) 1−2 and Be(NO) compounds. 17,19 Ammonia is found to interact in a completely different manner with Be. Ammonia is a strong σ-donor, but unlike CO it cannot ease π-back-donation.…”