A Spin-Frustrated Azide- and Alkoxide-Bridged Heterobimetallic Mixed-Valence Mn^IIMn^III₂Ni^II₄ Disc with <i>S</i> = 17/2 or 19/2

Seven-membered homometallic FeIII7, MnIII3MnII4 coordination clusters were previously reported to be spin-frustrated molecular discs. Herein, a mixed bimetallic and mixed-valence dicationic [MnIIMnIII2NiII4(N3)4(hmp)10](NO3)2 (12+(NO3)2) was isolated in pure form without scrambling of Ni/Mn ions. It was structurally characterized by single-crystal X-ray single-crystal diffraction. The presence of MnII ions at the center of the disc has been confirmed by EPR measurements. The magnetic studies suggest that complex 12+(NO3)2 possesses spin frustration with spin ground states S = 17/2 and 19/2, which has been studied and supported by DFT calculation. The purity of 12+(NO3)2 was confirmed by powder XRD measurements, and the ratio of Ni:Mn = 4:3 was further determined by SEM-EDX analysis

A Spin-Frustrated Azide- and Alkoxide-Bridged Heterobimetallic Mixed-Valence Mn^IIMn^III₂Ni^II₄ Disc with <i>S</i> = 17/2 or 19/2

Seven-membered homometallic FeIII7, MnIII3MnII4 coordination clusters were previously reported to be spin-frustrated molecular discs. Herein, a mixed bimetallic and mixed-valence dicationic [MnIIMnIII2NiII4(N3)4(hmp)10](NO3)2 (12+(NO3)2) was isolated in pure form without scrambling of Ni/Mn ions. It was structurally characterized by single-crystal X-ray single-crystal diffraction. The presence of MnII ions at the center of the disc has been confirmed by EPR measurements. The magnetic studies suggest that complex 12+(NO3)2 possesses spin frustration with spin ground states S = 17/2 and 19/2, which has been studied and supported by DFT calculation. The purity of 12+(NO3)2 was confirmed by powder XRD measurements, and the ratio of Ni:Mn = 4:3 was further determined by SEM-EDX analysis

Estimation of σ‑Donation and π‑Backdonation of Cyclic Alkyl(amino) Carbene-Containing Compounds

Herein, we present a general method for a reliable estimation of the extent of π-backdonation (C_cAAC←E) of the bonded element (E) to the carbene carbon atom and C_cAAC→E σ-donation. The C_cAAC←E π-backdonation has a significant effect on the electronic environments of the ¹⁵N nucleus. The estimation of the π-backdonation has been achieved by recording the chemical shift values of the ¹⁵N nuclei via two-dimensional heteronuclear multiple-bond correlation spectroscopy. The chemical shift values of the ¹⁵N nuclei of several cAAC-containing compounds and/or complexes were recorded. The ¹⁵N nuclear magnetic resonance chemical shift values are in the range from −130 to −315 ppm. When the cAAC forms a coordinate σ-bond (C_cAAC→E), the chemical shift values of the ¹⁵N nuclei are around −160 ppm. In case the cAAC is bound to a cationic species, the numerical chemical shift value of the ¹⁵N nucleus is downfield-shifted (−130 to −148 ppm). The numerical values of the ¹⁵N nuclei fall in the range from −170 to −200 ppm when σ-donation (C_cAAC→E) of cAAC is stronger than C_cAAC←E π-backacceptance. The π-backacceptance of cAAC is stronger than σ-donation, when the chemical shift values of the ¹⁵N nuclei are observed below −220 ppm. Electron density and charge transfer between C_cAAC and E are quantified using natural bonding orbital analysis and charge decomposition analysis techniques. The experimental results have been correlated with the theoretical calculations. They are in good agreement

Lewis Base Stabilized Group 14 Metalylenes

The chemistry of stable metalylenes (the heavier group 14 element analogues of carbenes) is an intriguing target of main group chemistry due to their synthetic potential and industrial application. In the present study, we report on the utilization of an abnormal N-heterocyclic carbene (aNHC) and a cyclic alkyl-amino carbene (cAAC) as a Lewis base for the syntheses of compounds aNHC·SiCl₂ (<b>3</b>), aNHC·SnCl₂ (<b>4</b>), and cAAC·SnCl₂ (<b>5</b>). The synthesis of silylene <b>3</b> involved the ligand-substitution reaction between NHC·SiCl₂ and an aNHC. However, compounds <b>4</b> and <b>5</b> were synthesized by the reactions of aNHC and cAAC with SnCl₂ in the molar ratio of 1:1. Compounds <b>3</b>–<b>5</b> are well-characterized with various spectroscopic methods and single-crystal X-ray structural analysis

N–P Bond Cleavage Induced Ring Formation of Cyclosilazanes from Reactions of Aryl(phosphanyl)aminotrichlorosilanes with Lithium Alkynyls

The aryl­(silyl)­aminotrichlorosilane 2,6-<i>i</i>Pr₂C₆H₃N­(SiMe₂Ph)­SiCl₃ (<b>1</b>) and aryl­(phosphanyl)­aminotrichlorosilane ArN­(PPh₂)­SiCl₃ (Ar = 2,6-<i>i</i>Pr₂C₆H₃ (<b>2</b>), 4-MeC₆H₄ (<b>3</b>), 2,4,6-Me₃C₆H₂ (<b>4</b>)) were prepared and utilized for investigation in reactions with freshly prepared lithium alkynyls. Reaction of <b>1</b> with PhCCLi resulted in the compounds PhMe₂SiCCPh and 2,6-<i>i</i>Pr₂C₆H₃N­[Li­(THF)₃]­Si­(CCPh)₃ (<b>5</b>), while <b>2</b> reacted with R′CCLi to produce the compounds Ph₂PCCR′ and [2,6-<i>i</i>Pr₂C₆H₃NSi­(CCR′)₂]₂ (R′ = Ph (<b>6</b>), <i>t</i>Bu (<b>7</b>), CH₂CH₂Ph (<b>8</b>)). Reaction of <b>3</b> with PhCCLi led to the formation of Ph₂PCCPh and [4-MeC₆H₄NSi­(CCPh)₂]₃ (<b>9a</b>) as a major product and {4-MeC₆H₄NSi­(CCPh)­[N­(4-MeC₆H₄)­Si­(CCPh)₃]}₂ (<b>9b</b>) as a minor product. When <b>4</b> was reacted with PhCCLi, [2,4,6-Me₃C₆H₂NSi­(CCPh)₂]₂ (<b>10a</b>) was isolated as the major product while [(2,4,6-Me₃C₆H₂)₃N₃Si₂(CCPh)₄Li­(THF)]⁻[Li­(THF)₄]⁺ (<b>10b</b>) was the minor product. The formation of Ph₂PCCPh was also detected. All reported compounds were characterized by multinuclear NMR (¹H, ¹³C, ²⁹Si, and/or ³¹P) and/or IR spectroscopy, and compounds <b>2</b>, <b>5</b>–<b>8</b>, <b>9a</b>, and <b>10b</b> were further distinguished by single-crystal X-ray crystallography. These results exhibit a route to the Si₂N₂- or Si₃N₃-based cyclosilazanes <b>6</b>–<b>8</b>, <b>9a</b>, <b>9b</b>, and <b>10a</b> via the N–P bond cleavage of the aryl­(phosphanyl)­aminotrichlorosilanes during multiple metathesis reactions

Lewis Base Stabilized Group 14 Metalylenes

The chemistry of stable metalylenes (the heavier group 14 element analogues of carbenes) is an intriguing target of main group chemistry due to their synthetic potential and industrial application. In the present study, we report on the utilization of an abnormal N-heterocyclic carbene (aNHC) and a cyclic alkyl-amino carbene (cAAC) as a Lewis base for the syntheses of compounds aNHC·SiCl₂ (<b>3</b>), aNHC·SnCl₂ (<b>4</b>), and cAAC·SnCl₂ (<b>5</b>). The synthesis of silylene <b>3</b> involved the ligand-substitution reaction between NHC·SiCl₂ and an aNHC. However, compounds <b>4</b> and <b>5</b> were synthesized by the reactions of aNHC and cAAC with SnCl₂ in the molar ratio of 1:1. Compounds <b>3</b>–<b>5</b> are well-characterized with various spectroscopic methods and single-crystal X-ray structural analysis

Acyclic Germylones: Congeners of Allenes with a Central Germanium Atom

The cyclic alkyl­(amino) carbene (cAAC:)-stabilized acyclic germylones (Me₂-cAAC:)₂Ge (<b>1</b>) and (Cy₂-cAAC:)₂Ge (<b>2</b>) were prepared utilizing a one-pot synthesis of GeCl₂(dioxane), cAAC:, and KC₈ in a 1:2:2.1 molar ratio. Dark green crystals of compounds <b>1</b> and <b>2</b> were produced in 75 and 70% yields, respectively. The reported methods for the preparation of the corresponding silicon compounds turned out to be not applicable in the case of germanium. The single-crystal X-ray structures of <b>1</b> and <b>2</b> feature the C–Ge–C bent backbone, which possesses a three-center two-electron π-bond system. Compounds <b>1</b> and <b>2</b> are the first acyclic germylones containing each one germanium atom and two cAAC: molecules. EPR measurements on compounds <b>1</b> and <b>2</b> confirmed the singlet spin ground state. DFT calculations on <b>1</b>/<b>2</b> revealed that the singlet ground state is more stable by ∼16 to 18 kcal mol^–1 than that of the triplet state. First and second proton affinity values were theoretically calculated to be of 265.8 (<b>1</b>)/267.1 (<b>2</b>) and 180.4 (<b>1</b>)/183.8 (<b>2</b>) kcal mol^–1, respectively. Further calculations, which were performed at different levels suggest a singlet diradicaloid character of <b>1</b> and <b>2</b>. The TD-DFT calculations exhibit an absorption band at ∼655 nm in <i>n</i>-hexane solution that originates from the diradicaloid character of germylones <b>1</b> and <b>2</b>

Acyclic Germylones: Congeners of Allenes with a Central Germanium Atom

The cyclic alkyl­(amino) carbene (cAAC:)-stabilized acyclic germylones (Me₂-cAAC:)₂Ge (<b>1</b>) and (Cy₂-cAAC:)₂Ge (<b>2</b>) were prepared utilizing a one-pot synthesis of GeCl₂(dioxane), cAAC:, and KC₈ in a 1:2:2.1 molar ratio. Dark green crystals of compounds <b>1</b> and <b>2</b> were produced in 75 and 70% yields, respectively. The reported methods for the preparation of the corresponding silicon compounds turned out to be not applicable in the case of germanium. The single-crystal X-ray structures of <b>1</b> and <b>2</b> feature the C–Ge–C bent backbone, which possesses a three-center two-electron π-bond system. Compounds <b>1</b> and <b>2</b> are the first acyclic germylones containing each one germanium atom and two cAAC: molecules. EPR measurements on compounds <b>1</b> and <b>2</b> confirmed the singlet spin ground state. DFT calculations on <b>1</b>/<b>2</b> revealed that the singlet ground state is more stable by ∼16 to 18 kcal mol^–1 than that of the triplet state. First and second proton affinity values were theoretically calculated to be of 265.8 (<b>1</b>)/267.1 (<b>2</b>) and 180.4 (<b>1</b>)/183.8 (<b>2</b>) kcal mol^–1, respectively. Further calculations, which were performed at different levels suggest a singlet diradicaloid character of <b>1</b> and <b>2</b>. The TD-DFT calculations exhibit an absorption band at ∼655 nm in <i>n</i>-hexane solution that originates from the diradicaloid character of germylones <b>1</b> and <b>2</b>

Acyclic Germylones: Congeners of Allenes with a Central Germanium Atom

The cyclic alkyl­(amino) carbene (cAAC:)-stabilized acyclic germylones (Me₂-cAAC:)₂Ge (<b>1</b>) and (Cy₂-cAAC:)₂Ge (<b>2</b>) were prepared utilizing a one-pot synthesis of GeCl₂(dioxane), cAAC:, and KC₈ in a 1:2:2.1 molar ratio. Dark green crystals of compounds <b>1</b> and <b>2</b> were produced in 75 and 70% yields, respectively. The reported methods for the preparation of the corresponding silicon compounds turned out to be not applicable in the case of germanium. The single-crystal X-ray structures of <b>1</b> and <b>2</b> feature the C–Ge–C bent backbone, which possesses a three-center two-electron π-bond system. Compounds <b>1</b> and <b>2</b> are the first acyclic germylones containing each one germanium atom and two cAAC: molecules. EPR measurements on compounds <b>1</b> and <b>2</b> confirmed the singlet spin ground state. DFT calculations on <b>1</b>/<b>2</b> revealed that the singlet ground state is more stable by ∼16 to 18 kcal mol^–1 than that of the triplet state. First and second proton affinity values were theoretically calculated to be of 265.8 (<b>1</b>)/267.1 (<b>2</b>) and 180.4 (<b>1</b>)/183.8 (<b>2</b>) kcal mol^–1, respectively. Further calculations, which were performed at different levels suggest a singlet diradicaloid character of <b>1</b> and <b>2</b>. The TD-DFT calculations exhibit an absorption band at ∼655 nm in <i>n</i>-hexane solution that originates from the diradicaloid character of germylones <b>1</b> and <b>2</b>

Acyclic Germylones: Congeners of Allenes with a Central Germanium Atom

The cyclic alkyl­(amino) carbene (cAAC:)-stabilized acyclic germylones (Me₂-cAAC:)₂Ge (<b>1</b>) and (Cy₂-cAAC:)₂Ge (<b>2</b>) were prepared utilizing a one-pot synthesis of GeCl₂(dioxane), cAAC:, and KC₈ in a 1:2:2.1 molar ratio. Dark green crystals of compounds <b>1</b> and <b>2</b> were produced in 75 and 70% yields, respectively. The reported methods for the preparation of the corresponding silicon compounds turned out to be not applicable in the case of germanium. The single-crystal X-ray structures of <b>1</b> and <b>2</b> feature the C–Ge–C bent backbone, which possesses a three-center two-electron π-bond system. Compounds <b>1</b> and <b>2</b> are the first acyclic germylones containing each one germanium atom and two cAAC: molecules. EPR measurements on compounds <b>1</b> and <b>2</b> confirmed the singlet spin ground state. DFT calculations on <b>1</b>/<b>2</b> revealed that the singlet ground state is more stable by ∼16 to 18 kcal mol^–1 than that of the triplet state. First and second proton affinity values were theoretically calculated to be of 265.8 (<b>1</b>)/267.1 (<b>2</b>) and 180.4 (<b>1</b>)/183.8 (<b>2</b>) kcal mol^–1, respectively. Further calculations, which were performed at different levels suggest a singlet diradicaloid character of <b>1</b> and <b>2</b>. The TD-DFT calculations exhibit an absorption band at ∼655 nm in <i>n</i>-hexane solution that originates from the diradicaloid character of germylones <b>1</b> and <b>2</b>