Eighty three stationary points of MgC6H2 isomers spanning from 0 to 215 kcal mol–1 have been theoretically identified using density functional theory at the B3LYP/6-311++G­(2d,2p) level of theory. Among them, four low-lying isomers lying within 23.06 kcal mol–1 (1 eV) have been further characterized in detail using high-level coupled-cluster (CC) methods. The thermodynamically most stable isomer turns out to be 1-magnesacyclohepta-4-en-2,6-diyne (1). The other three isomers, 3-magnesahepta-1,4,6-triyne (2), 1-magnesacyclohepta-2,3,4-trien-6-yne (3), and 1-magnesahepta-2,4,6-triyne (4) lie 8.24, 19.76, and 21.36 kcal mol–1, respectively, above 1 at the ae-CCSD­(T)/cc-pCVTZ level of theory. All the four isomers are polar with a permanent electric dipole moment (μ ≠ 0). Hence, they are potential candidates for rotational spectroscopic studies. Considering the recent identification of magnesium-bearing hydrocarbons such as, MgC2H and MgC4H in IRC+10216, it is believed that the current theoretical data may be of relevance to laboratory molecular spectroscopic and radioastronomical studies on MgC6H2 isomers. The energetic and spectroscopic information gathered in this study would aid the detection of low-lying MgC6H2 isomers in the laboratory, which are indispensable for radioastronomical studies. It is also noted here that neither the National Institute of Standards and Technology Chemistry WebBook nor the Kinetic Database for Astrochemistry lists any isomer of MgC6H2 at the moment. Therefore, these isomers are studied here theoretically for the very first time.

Novel organomagnesium crown ether molecules have been computationally characterized using density functional theory (DFT). Monomer units of MgC 6 are used as building blocks. Isomers of MgC 6 H 2 have been extensively explored using both DFT and coupled-cluster methods in the past by some of us. It had been concluded that the seven-membered ring isomer, 1magnesacyclohept-4-en-2,6-diyne, was the thermodynamically most stable molecule at all levels. Thus, the latter has been used as the building block for designing new organomagne-sium crown ethers. Both alkali (Li + , Na + , and K + ) and alkalineearth (Be 2 + , Mg 2 + , and Ca 2 + ) metal ions selective complexes have been theoretically identified. Theoretical binding energies (~E at 0 K) and thermally corrected Gibbs free energies (~G at 298.15 K) have been computed for these molecules with MgC 6 -6-crown-2, MgC 6 -9-crown-3, and MgC 6 -12-crown-4 hosts. Higher binding affinity values obtained for Be 2 + indicate that these new crown ether molecules could effectively be used for Be 2 + encapsulation.

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Novel organomagnesium crown ether molecules have been computationally characterized for the first time using density functional theory (DFT). Monomer units of MgC6 have been used as building blocks. The potential energy surface of the parent elemental composition, MgC6H2, has been extensively explored using both DFT and coupled-cluster methods. It is concluded that the seven-membered ring isomer, 1-magnesacyclohept-4-en-2,6-diyne, is the thermodynamically most stable molecule at all levels. Thus, the latter has been used as the building block for organomagnesium crown ethers. Both alkali (Li+, Na+, and K+) and alkaline-earth (Be2+, Mg2+, and Ca2+) metal ions selective complexes have been theoretically identified. Binding energies (Delta E at 0 K) and thermally corrected Gibbs free energies (Delta G at 298.15 K) have<br>been computed for these metal ions with MgC6-9-crown-3 and MgC6-12-crown-4 to gauge their binding affinities.Novel organomagnesium crown ether molecules have been computationally characterized for the first time using density functional theory (DFT). Monomer units of MgC6 have been used as building blocks. The potential energy surface of the parent elemental composition, MgC6H2, has been extensively explored using both DFT and coupled-cluster methods. It is concluded that the seven-membered ring isomer, 1-magnesacyclohept-4-en-2,6-diyne, is the thermodynamically most stable molecule at all levels. Thus, the latter has been used as the building block for organomagnesium crown ethers. Both alkali (Li+, Na+, and K+) and alkaline-earth (Be2+, Mg2+, and Ca2+) metal ions selective complexes have been theoretically identified. Binding energies (Delta E at 0 K) and thermally corrected Gibbs free energies (Delta G at 298.15 K) have been computed for these metal ions with MgC6-9-crown-3 and MgC6-12-crown-4 to gauge their binding affinities.

Novel organomagnesium crown ether molecules have been computationally characterized for the first time using density functional theory (DFT). Monomer units of MgC6 have been used as building blocks. The potential energy surface of the parent elemental composition, MgC6H2, has been extensively explored using both DFT and coupled-cluster methods. It is concluded that the seven-membered ring isomer, 1-magnesacyclohept-4-en-2,6-diyne, is the thermodynamically most stable molecule at all levels. Thus, the latter has been used as the building block for organomagnesium crown ethers. Both alkali (Li+, Na+, and K+) and alkaline-earth (Be2+, Mg2+, and Ca2+) metal ions selective complexes have been theoretically identified. Binding energies (Delta E at 0 K) and thermally corrected Gibbs free energies (Delta G at 298.15 K) have<br>been computed for these metal ions with MgC6-9-crown-3 and MgC6-12-crown-4 to gauge their binding affinities.Novel organomagnesium crown ether molecules have been computationally characterized for the first time using density functional theory (DFT). Monomer units of MgC6 have been used as building blocks. The potential energy surface of the parent elemental composition, MgC6H2, has been extensively explored using both DFT and coupled-cluster methods. It is concluded that the seven-membered ring isomer, 1-magnesacyclohept-4-en-2,6-diyne, is the thermodynamically most stable molecule at all levels. Thus, the latter has been used as the building block for organomagnesium crown ethers. Both alkali (Li+, Na+, and K+) and alkaline-earth (Be2+, Mg2+, and Ca2+) metal ions selective complexes have been theoretically identified. Binding energies (Delta E at 0 K) and thermally corrected Gibbs free energies (Delta G at 298.15 K) have been computed for these metal ions with MgC6-9-crown-3 and MgC6-12-crown-4 to gauge their binding affinities.