Structures and Energetics of E2H3+ (E = As, Sb, and Bi) Cations

E2H2 (E = As, Sb, Bi) structures involving multiple bonds have attracted much attention recently. The E2H3+ cations (protonated E2H2) are predicted to be viable with substantial proton affinities (>180 kcal/mol). Herein, the bonding characters and energetics of a number of E2H3+ isomers are explored through CCSD(T) and DFT methods. For the As2H3+ system, the CCSD(T)/cc-pVQZ-PP method predicts that the vinylidene-like structure lies lowest in energy, with the trans and cis isomers higher by 6.7 and 9.3 kcal/mol, respectively. However, for Sb2H3+ and Bi2H3+ systems, the trans isomer is the global minimum, while the energies of the cis and vinylidene-like structures are higher, respectively, by 2.0 and 2.4 kcal/mol for Sb2H3+ and 1.6 and 15.0 kcal/mol for Bi2H3+. Thus, the vinyledene-like structure is the lowest energy for the arsenic system but only a transition state of the bismuth system. With permanent dipole moments, all minima may be observable in microwave experiments. Besides, we have also obtained transition states and planar-cis structures with higher energies. The current results should provide new insights into the various isomers and provide a number of predictions for future experiments.

Unusual Structures of the Parent Molecules Diarsene, Distibene, and Dibismuthene: Toward Their Observation

There is considerable interest, from both experimental and theoretical perspectives, in molecules incorporating multiple bonds between main group elements. Herein, we not only consider the parent molecules HE=EH (E=As, Sb, Bi), but also a number of their isomers. For each E₂ H₂ molecule, a number of different structures were optimized with four different DFT methods. Final structures were determined with the coupled cluster method CCSD(T) using large basis sets, namely cc-pVQZ-PP, incorporating relativistic psuedopotentials. All feasible dissociation pathways are examined. For all three E₂ H₂ molecules the trans isomer lies lowest in energy, with the cis isomer higher by 2.7 (As), 2.1 (Sb), and 1.8 (Bi) kcal mol^-1 , respectively. However, both cis and trans structures should be observable, as large barriers (27.7, 20.5, and 17.7 kcal mol^-1 ) separate them. For both the cis and trans structures, in the infrared the strong E-H stretching frequencies should also be observable. Only the cis structures have dipole moments (0.62, 0.01, and 0.83 debye, respectively), and their observation by microwave spectroscopy would be stunning. Also considered were the higher energy vinylidene-like, pyramidal, monobridged, and linear structures. We conclude that molecules such as HSb=SbH-Fe(CO)₄ , HBi=BiH-Fe(CO)₄ , and related systems, should be feasible synthetic targets.

The Parent Diarsene HAs=AsH as Side-on Bound Ligand in an Iron Carbonyl Complex

The terminal diarsene HAs=AsH ligand attracts special interest concerning its bonding relation in comparison to its isolable relative, ethene. Herein, by the methanolysis of [{Fe(CO)₄}As(SiMe₃)₃] (1) the synthesis of [{Fe(CO)₄}(η²‐As₂H₂)] (2) is reported, containing a parent diarsene as unprecedented side‐on coordinated ligand. Following this synthetic route, also the D‐labeled complex [{Fe(CO)₄}(η²‐As₂D₂)] (2D) could be isolated. The electronic structure and bonding situation of 2 was elucidated by DFT calculations revealing that 2 is best described as an olefin‐like complex. Moreover, the reactivity of 2 towards the Lewis acids [{M(CO)₅}(thf)] (M=Cr, W) was investigated, leading to the complexes [Fe(CO)₄AsHW(CO)₅]₂ (3) and [{Fe(CO)₄}₂AsH{Cr(CO)₅}] (4), respectively.

Double-bond elucidation for arsagermene with a tricoordinate germanium center: a theoretical survey

Multiple-bonded heteronuclear combinations have recently received great attention because of the first experimental arsagermene (>GeAs–) synthesis, which is a relevant topic in organometallic chemistry.

Tailoring the electronic properties among oxoarsine, arsinoyl and arsine oxide isomers: the simplest molecular systems with an arsenic–oxygen bond

The main goal of this investigation is to understand the reaction pathways and the electronic and spectroscopy properties of AsOH_n radicals (n = 0–3), which are some of the simplest compound models with an arsenic–oxygen bond.

Isolation of Elusive HAsAsH in a Crystalline Diuranium(IV) Complex

The HAsAsH molecule has hitherto only been proposed tentatively as a short-lived species generated in electrochemical or microwave-plasma experiments. After two centuries of inconclusive or disproven claims of HAsAsH formation in the condensed phase, we report the isolation and structural authentication of HAsAsH in the diuranium(IV) complex [{U(TrenTIPS)}2(μ-η2:η2-As2H2)] (3, TrenTIPS=N(CH2CH2NSiPri3)3; Pri=CH(CH3)2). Complex 3 was prepared by deprotonation and oxidative homocoupling of an arsenide precursor. Characterization and computational data are consistent with back-bonding-type interactions from uranium to the HAsAsH π*-orbital. This experimentally confirms the theoretically predicted excellent π-acceptor character of HAsAsH, and is tantamount to full reduction to the diarsane-1,2-diide form.

Isolation of Elusive HAsAsH in a Crystalline Diuranium(IV) Complex

The HAsAsH molecule has hitherto only been proposed tentatively as a short-lived species generated in electrochemical or microwave-plasma experiments. After two centuries of inconclusive or disproven claims of HAsAsH formation in the condensed phase, we report the isolation and structural authentication of HAsAsH in the diuranium(IV) complex [{U(Tren^TIPS)}₂(μ-η²:η²-As₂H₂)] (3, Tren^TIPS=N(CH₂CH₂NSiPrⁱ₃)₃; Prⁱ=CH(CH₃)₂). Complex 3 was prepared by deprotonation and oxidative homocoupling of an arsenide precursor. Characterization and computational data are consistent with back-bonding-type interactions from uranium to the HAsAsH π*-orbital. This experimentally confirms the theoretically predicted excellent π-acceptor character of HAsAsH, and is tantamount to full reduction to the diarsane-1,2-diide form.