Theoretical assessing on the coordination mode and bonding in heteronuclear group‐13 dimetallocene

In this article, the coordination mode, the nature of metal–ligand interaction and dimetallic bonding in heteronuclear group‐13 dimetallocene (CpMM′CpI₂; Cp = C₅H₅, M/M′=B, Al, Ga, In, and Tl) have been investigated within the framework of the atoms in molecules theory, electron localization function, and energy decomposition analysis. The calculated results show that the symmetries of the title compounds, the coordination modes between the metal and ligand, the strength and nature of M‐ligand interaction and M M′ bond are well correlated with the periodicity changing of group‐13 metal atom going from the lighter to the heavier (B, Al, Ga, In, and Tl). The heavier group 13 metal atom is corresponding to the higher symmetry, stronger metal–ligand interaction, and weaker dimetallic bond. The covalent characters of both metal–ligand interaction and dimetallic bond are decreasing in the sequence of M′=Al, Ga, In, and Tl, for the same M atom.     

Theoretical designs for neutral five-membered carbene analogues of the group 13 elements: a new target for synthesis

Potential energy surfaces for the chemical reactions of neutral five-membered group 13 carbenoids have been studied using density functional theory (B3LYP/LANL2DZ). Five five-membered group 13 carbenoid species, HCMeP(PhN)2X, where X = B, Al, Ga, In, and Tl, have been chosen as model reactants in this work. Also, three kinds of chemical reaction, C-H bond insertion, alkene cycloaddition, and dimerization, have been used to study the chemical reactivities of these group 13 carbenoids. Our present theoretical work predicts that the larger the angleNXN bond angle in the neutral five-membered group 13 carbenoid, the smaller the singlet-triplet splitting, the lower the activation barrier, and, in turn, the more rapid are its various chemical reactions. Moreover, the theoretical investigations suggest that the relative carbenoidic reactivity decreases in the order B > Al > Ga > In > Tl. That is, the heavier the group 13 atom (X), the more stable is its carbenoid with respect to chemical reactions. As a result, we predict that the neutral five-membered group 13 carbenoids (X = Al, Ga, In, and Tl) should be stable, readily synthesized, and isolated at room temperature. Furthermore, the neutral five-membered group 13 carbenoid singlet-triplet energy splitting, as described in the configuration mixing model attributed to the work of Pross and Shaik, can be used as a diagnostic tool to predict their reactivities. The results obtained allow a number of predictions to be made.     

Reversal of stability on metalation of pentagonal-bipyramidal (1-MB6H7(2-) 1-M-2-CB5H7(1-) and 1-M-2,4-C2B4H7) and Icosahedral (1-MB11H12(2-) 1-M-2-CB10H12(1-) and 1-M-2,4-C2B9H12) boranes (M = Al, Ga, In, and Tl): energetics of condensation and relationship to binuclear metallocenes

The usual assumption of the extra stability of icosahedral boranes (2) over pentagonal-bipyramidal boranes (1) is reversed by substitution of a vertex by a group 13 metal. This preference is a result of the geometrical requirements for optimum overlap between the five-membered face of the ligand and the metal fragment. Isodesmic equations calculated at the B3LYP/LANL2DZ level indicate that the extra stability of 1-M-2,4-C(2)B(4)H(7) varies from 14.44 kcal/mol (M = Al) to 15.30 kcal/mol (M = Tl). Similarly, M(2,4-C(2)B(4)H(6))(2)(1-) is more stable than M(2,4-C(2)B(9)H(11))(2)(1-) by 9.26 kcal/mol (M = Al) and by 6.75 kcal/mol (M = Tl). The preference for (MC(2)B(4)H(6))(2) over (MC(2)B(9)H(11))(2) at the same level is 30.54 kcal/mol (M = Al), 33.16 kcal/ mol (M = Ga) and 37.77 kcal/mol (M = In). The metal-metal bonding here is comparable to those in CpZn-ZnCp and H(2)M-MH(2) (M= Al, Ga, and In).     

Theoretical studies of the [2 + 4] Diels-Alder cycloaddition reactions of alkene analogues of the group 13 elements with toluene

The potential energy surfaces for the cycloaddition reactions of formally double-bonded molecules containing group 13 elements have been studied using density functional theory (B3LYP/LANL2DZ). Five group 13 alkene analogues, ArX=XAr, where X = B, Al, Ga, In, and Tl, have been chosen as model reactants in this work. Our present theoretical work predicts that the smaller the singlet-triplet splitting in ArX=XAr, the lower the activation barrier and, in turn, the more rapid are its [4 + 2] cycloaddition reactions. Moreover, the theoretical investigations suggest that the relative dimeric reactivity decreases in the order B > Al > Ga > In > Tl. That is, the heavier the group 13 atom (X), the more stable is its dimetallene toward chemical reactions. In consequence, our results predict that the dimetallenes containing heavier group 13 elements (in particular, X = Ga, In, and Tl) should be stable and should be readily synthesized and isolated at room temperature. This is in good agreement with available experimental observations. Besides this, the singlet-triplet energy splitting of a dimetallene, as described in the configuration mixing model attributed to the work of Pross and Shaik, can be used as a diagnostic tool to predict its reactivity. The results obtained allow a number of predictions to be made.     

Thermodynamic calculation of the solubility of solid hydroxides of group IIIA elements in water and aqueous media

The effect of pH on the molar solubility of amorphous and crystalline hydroxides M(OH)₃ and metahydroxides MO(OH), where M is B, Al, Ga, In, or Tl, in aqueous alkaline and acidic media at 25°C was calculated thermodynamically taking into account the formation of hydroxo complexes.     

Density functional theoretical study of a series of binary azides M(N3)n (n = 3, 4)

Geometrical structures of a series of binary azides M(N3)n (M = elements in groups 3 and 13 (n = 3) and in groups 4 and 14 (n = 4)) were investigated at the B3LYP/6-311+G level of theory. Our calculations found that binary group 3 triazides M(N3)3 (M = Sc, Y, La) and binary group 4 tetraazides M(N3)4 (M = Ti, Zr, Hf) turn out to be stable with all frequencies real having a similar linear M-N-NN structural feature, as previously reported for M(N3)4 (M = Ti, Zr, Hf). However, binary azides of group 13 M(N3)3 (M = B, Al, Ga, In, Tl) and group 14 elements M(N3)4 (C, Si, Ge, Sn, Pb) with bent M-N-NN bond angles differ obviously from binary group 3 and 4 azides in geometrical structure. These facts are mainly explained by the difference in electronic density overlap between the central atom and the alpha-N atoms of the azido groups. Two lone-pair electrons on the sp hybridization alpha-N atoms in the binary group 3 and 4 azides donate electron density into two empty d orbitals of the central transition metal atom and a pair of valence bonding electrons, resulting in the alpha-N atoms acting as a tridentate ligand. The sp2 hybridization alpha-N atoms of the binary group 13 and 14 azides only give one valence electron to form one valence bonding electron pair acting virtually as monodentate donors.     

ChemInform Abstract: Quantum‐Chemical Calculations and IR Spectra of the (F2)MF2 Molecules (M: B,Al, Ga,In, Tl) in Solid Matrices: A New Class of Very High Electron Affinity Neutral Molecules.

The new class of neutral adduct molecules (F₂)MF₂ (M: B, Al, Ga, In, Tl) forms by reaction of laser‐ablated group 13 metal atoms with F₂ in excess Ar and Ne during condensation at 5 K.     

Characterization of hydrated Na+(phenol) and K+(phenol) complexes using infrared spectroscopy

Hydrated alkali metal ion-phenol complexes were studied to model these species in aqueous solution for M=Na and K. IR predissociation spectroscopy in the O-H stretch region was used to analyze the structures of M+(Phenol)(H2O)n cluster ions, for n = 1-4. The onset of hydrogen bonding was observed to occur at n=4. Ab initio calculations were used to qualitatively explore the types of hydrogen-bonded structures of the M+(Phenol)(H2O)4 isomers. By combining the ab initio calculations and IR spectra, several different structures were identified for each metal ion. In contrast to benzene, detailed in a previous study of Na+(Benzene)n(H2O)m [J. Chem. Phys. 110, 8429 (1999)], phenol is able to bind directly to Na+ even in the presence of four waters. This is likely the result of the sigma-type interaction between the phenol oxygen and the ion. With K+, the dominant isomers are those in which the phenol O-H group is involved in a hydrogen bond with the water molecules, while with Na+, the dominant isomers are those in which the phenol O-H group is free and the water molecules are hydrogen-bonded to each other. Spectra and ab initio calculations for the M+(Phenol)Ar cluster ions for M=Na and K are reported to characterize the free phenol O-H stretch in the M+(Phenol) complex. While pi-type configurations were observed for binary M+(Phenol) complexes, sigma-type configurations appear to dominate the hydrated cluster ions.     

Theoretical investigations of the reactivities of four-membered N-heterocyclic carbene analogues of the group 13 elements

The potential energy surfaces for the chemical reactions of four‐membered N‐heterocyclic group 13 heavy carbeneoid species have been studied using density functional theory (Becke, 3‐parameter, Lee‐Yang‐Parr (B3LYP)/Los Alamos National Laboratory 2‐Double‐Zeta (LANL2DZ)). Five four‐membered group 13 heavy carbeneoid species, iPr₂NC(NAr)₂E:, where E = B, Al, Ga, In, and Tl, have been chosen as model reactants in this work. Also, three kinds of chemical reactions, C? H bond insertion, alkene cycloaddition, and dimerization, have been used to study the chemical reactivities of these group 13 four‐membered N‐heterocyclic carbeneoid species. In principle, our present theoretical work predicts that the larger the ∠NEN bond angle of the four‐membered group 13 iPr₂NC(NAr)₂E: species, the smaller the singlet–triplet splitting, the lower the activation barrier, and, in turn, the more rapid its chemical reactions to various chemical species. Moreover, our theoretical investigations suggest that the relative carbenic reactivity decreases in the following order: B > Al > Ga > In > Tl. That is, the heavier the group 13 atom (E), the more stable its four‐membered carbeneoid toward chemical reactions is. As a result, our computations predict that the four‐membered heavy group 13 iPr₂NC(NAr)₂E: species (E = Al, Ga, In, and Tl) should be both kinetically and thermodynamically stable, and can be readily synthesized and isolated at room temperature. Furthermore, the singlet–triplet energy splitting of the four‐membered group 13 iPr₂NC(NAr)₂E: species, as described in the configuration mixing model attributed to the work of Pross and Shaik, can be used as a diagnostic tool to predict their reactivities. The results obtained allow a number of predictions to be made. © 2011 Wiley Periodicals, Inc. J Comput Chem, 2011     

New structural motif of 18 valence electron molecules with a planar tetracoordinate heavier group 14 center: Unique stabilization effect of a π‐type skeleton

Proposing new valence electron counting rules and new structural motifs are both very important in chemistry. In this work, we unexpectedly found that by introducing a π‐type skeleton YCCY (Y = Al/Ga/In/Tl), a total of sixteen novel planar tetracoordinate heavier group 14 species, that is, ptM (M = Si/Ge/Sn/Pb) in neutral, can be designed as global minima. The underlying bonding situation contrasts sharply both with the well‐known 18ve‐ptC and the limited 18ve‐ptM, for which there is little multiple bonding character within the skeleton. The fact that each YCCY (Y = Al/Ga/In/Tl) can stabilize all heavier group 14 atoms in a planar tetracoordinate fashion strongly demonstrates the universality of such a π‐type skeleton. The present work firmly demonstrates that introducing the π‐type ligand skeleton can effectively enrich the planar tetracoordinate chemistry with the heavier group atoms.     

Low-valent group-13 chemistry. Theoretical investigation of the structures and relative stabilities of donor-acceptor complexes R(3)E[bond]E'R' and their isomers R(2)E[bond]E'RR'

The results of quantum chemical calculations at the gradient-corrected density functional theory (DFT) level with the B3LYP functional of the donor-acceptor complexes R(3)E[bond]E'R' and their isomers R(2)E[bond]E'RR', where E, E' = B[bond]Tl and R, R' = H, Cl, or CH(3), are reported. The theoretically predicted energy differences between the donor-acceptor form R(3)E[bond]E'R' and the classical isomer R(2)E[bond]E'RR' and the bond dissociation energies of the E[bond]E' bonds are given. The results are discussed in order to show which factors stabilize the isomers R(3)E[bond]E'R'. There is no simple correlation of the nature of the group-13 elements E, E' and the substituents R, R' with the stability of the complexes. The isomers R(3)E[bond]'R' come stabilized by pi donor groups R', while the substituents R may either be sigma- or pi-bonded groups. Calculations of Cl(3)B[bond]BR' [R' = Cl, cyclopentadienyl (Cp), or Cp*] indicate that the Cp* group has a particularly strong effect on the complex form. The calculations show that the experimentally known complex Cl(3)B[bond]BCp* is the strongest bonded donor-acceptor complex of main-group elements that has been synthesized until now. The theoretically predicted B[bond]B bond energy is D(o) = 50.6 kcal/mol. However, the calculations indicate that it should also be possible to isolate donor-acceptor complexes R(3)E[bond]E'R' where R' is a sigma-bonded bulky substituent. Possible candidates that are suggested for synthetic work are the borane complexes (C(6)F(5))(3)B[bond]E'R' and (t)Bu(3)B[bond]E'R' (E' = Al[bond]Tl) and the alane complexes Cl(3)Al[bond]E'R' (E' = Ga[bond]Tl).     

ⅥB族金属叁键有机化合物的研究进展

本文对一类重要的ⅥB族金属叁键化合物R~2M~2(CO)~4(R为环戊二烯基及类环戊二烯基)近年来的研究成果进行了综述, 综述重点是这类化合物的官能团M≡M叁键的化学活性, 全文包括R~2M~2(CO)~4的合成及结构, M≡M叁键与亲核试剂、与碳-碳重键、与氧或与金属羰基物等试剂的反应及其应用。     

Metal complexes of N-tosylamidoporphyrin: cis-acetato-N-tosylimido-meso-tetraphenylporphyrinatothallium(III) and trans-acetato-N-tosylimido-meso-tetraphenylporphyrinatogallium(III)

The crystal structures of acetato-N-tosylimido-meso-tetraphenylporphyrinatothallium(III), Tl(N-NTs-tpp)(OAc) (1), and acetato-N-tosylimido-meso-tetraphenylporphyrinatogallium(III), Ga(N-NTs-tpp)(OAc) (2), were determined. The coordination sphere around the Tl3+ ion is a distorted square-based pyramid in which the apical site is occupied by a chelating bidentate OAc- group, whereas for the Ga3+ ion, it is a distorted trigonal bipyramid with O(3), N(3), and N(5) lying in the equatorial plane. The porphyrin ring in the two complexes is distorted to a large extent. For the Tl3+ complex, the pyrrole ring bonded to the NTs ligand lies in a plane with a dihedral angle of 50.8 degrees with respect to the 3N plane, which contains the three pyrrole nitrogens bonded to Tl3+, but for the Ga3+ complex, this angle is found to be only 24.5 degrees. In the former complex, Tl3+ and N(5) are located on the same side at 1.18 and 1.29 A from its 3N plane, but in the latter one, Ga3+ and N(5) are located on different sides at -0.15 and 1.31 A from its 3N plane. The free energy of activation at the coalescence temperature Tc for the intermolecular acetate exchange process in 1 in CD2Cl2 solvent is found to be delta G++171 = 36.0 kJ/mol through 1H NMR temperature-dependent measurements. In the slow-exchange region, the methyl and carbonyl (CO) carbons of the OAc- group in 1 are separately located at delta 18.5 [3J(Tl-13C) = 220 Hz] and 176.3 [2J(Tl-13C) = 205 Hz] at -110 degrees C.     

Photoelectron spectroscopy and density functional theory of puckered ring structures of Group 13 metal-ethylenediamine

The ethylenediamine (en) complexes of Al, Ga, and In atoms were prepared in laser-vaporization supersonic molecular beams and studied with pulsed field ionization zero electron kinetic energy photoelectron spectroscopy and density functional theory. Several conformers of each metal complex are obtained by B3LYP calculations, and a five-membered cyclic structure is identified by combining the experimental measurements and theoretical calculations. Adiabatic ionization potentials, vibrational frequencies, and bond dissociation energies are determined for the ring structure. The ionization potentials of the Al, Ga, and In species are measured to be 32 784 (5), 33 324 (5), and 33 637 (7) cm(-1), respectively, and metal-ligand dissociation energies of the ionic and neutral complexes are calculated to be 60.2/16.2 (Al(+)/Al), 55.5/13.0 (Ga(+)/Ga), and 50.0/11.4 (In(+)/In) kcal mol(-1). Metal-ligand stretch and bend as well as a number of ligand-based vibrations are measured. Harmonic frequencies and anharmonicities of the M(+)-N (M=Al,Ga,In) stretch are determined for all three M(+)-en ions and the C-C-N bend of Ga(+)-en and In(+)-en. In comparison to monodentate methylamine, the bidentate binding of ethylenediamine leads to a significantly lower ionization potential and higher metal-ligand bond strength of the metal complexes.     

Structure,stability, and aromaticity of M?SubPc (MB,Al, and Ga): Computational study

A theoretical investigation on the structure, stability, and aromaticity of M‐subphthalocyanine (M? SubPc; M?B, Al, and Ga) was performed at the B3LYP/6‐31+G*//B3LYP/6‐31G* level. The comparison between M? SubPc and the corresponding M? phthalocyanine (M? Pc) was considered. The geometry optimization of the M? SubPc shows that in the Al? SubPc and Ga? SubPc, the steric repulsions among the three azacoupled isoindole moieties increase, as to their macrocycles tend to be far from planarity. The binding energies of Cl? M … aza‐coupled isoindole corrected by the basis set superposition error (BSSE), and the nucleus‐independent chemical shift (NICS) values at the ring center, which are a simple and effective local aromaticity probe, were calculated. The results show that Al? SubPc is less stable than both B? SubPc and Al? Pc for larger steric repulsion, smaller binding energy, and weaker aromaticity. In the same way, Ga? SubPc is less stable than both B? SubPc and Ga? Pc. In addition, the ring expansion reactivity occurring in B? SubPc was confirmed by the global aromaticity mirrored by the electrophilicity index ω values. Therefore, the Al? SubPc and Ga? SubPc remain unknown, while the corresponding compounds Al? Pc and Ga? Pc are known experimentally. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005     

Atranes

The PMR spectra of acidified solutions of metalloatrane-3,7,10-trione dihydrates containing a group-IIIB metal atom (M=Al, Ga, In, Tl) in D₂O were studied. The equivalence of the three atrane half-rings in all of the investigated molecules and of the methylene protons in each half-ring was proved. Spin-spin coupling of²⁰³Tl and²⁰⁵Tl with protons, which is apparently realized through a TlN transannular coordinate bond, is observed in the PMR spectrum of thallatrane-3,7,10-trione (M=Tl). The factors that determine the magnitudes of the chemical shifts of the methylene protons are discussed.See [1] for communication XXXII.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 312–314, March, 1973.     

Inverse sandwich complexes based on low‐valent group 13 elements and cyclobutadiene: A theoretical investigation on E‐C4H4‐E (E = Al,Ga, In,Tl)

The chemistry of the low‐valent Group 13 elements (E = B, Al, Ga, In, Tl) has formed the recent hot topic. Recently, a series of low‐valent Group 13‐based compounds have been synthesized, i.e., [E‐Cp*‐E]⁺ (E = Al, Ga, In, Tl) cations, which have been termed as the interesting “inverse sandwich” complexes. To enrich the family of inverse sandwiches, we report our theoretical design of a new type of inverse sandwiches E‐C₄H₄‐E (E = Al, Ga, In, Tl) for stabilizing the low‐valent Group 13 elements. The calculated dissociation energies indicate that unlike [E‐Cp‐E]⁺ that dissociates via loss of the charged atom E⁺, E‐C₄H₄‐E dissociates via loss of the neutral atom E with the bond strengths of Al > Ga > In > Tl. Moreover, E‐C₄H₄‐E are more stable in dissociation than [E‐Cp‐E]⁺ cations. By comparing with other various isomers, we found that the inverted E‐C₄H₄‐E should be kinetically quite stable with the least conversion barriers of 33.5, 33.5, 35.2, and 36.9 kcal/mol for E = Al, Ga, In, and Tl, respectively. Furthermore, replacement of cyclobutadiene‐H atoms by the highly electron‐positive groups such as SiH₃ and Si(CH₃)₃ could significantly stabilize the inverted form in thermodynamics. Possible synthetic routes are proposed for E‐C₄H₄‐E. With no need of counterions, the newly designed neutral complexes E‐C₄H₄‐E welcome future synthesis. © 2012 Wiley Periodicals, Inc.     

氧心羧桥异三核过渡金属簇合物[Fe2MO(CH3COO)6Py3].Py(1,M=Mn;2,M=Co;3,M=Ni)和[Fe2MO(CCl3COO)6(THF)3](4,M=Mn;5,M=Co;6,M=Ni)电子光谱的研究

The UV/VIS spectra for pyridine solution of complexes [Fe_2MO(CH_3COO)_6Py_2]·Py and THF solution of complexes Fe_2MO(CCl_3COO)_6(THF)_3 were studied. The d-d transitions were assigned and the ligand field parameters(B,D_q,β) were calculated for the related metal ions according to ligand field theory (Tanabe-Sugano diagram) in terms of O_h symmetry and reasonably good fits were obtained for the calculated and observed frequencies. The calculated results show that (1) the larger the ionic potential for M~(2+) ion, the larger the values of B, D_q for Fe~(3+) ion (2) the ligand field parameters of metal ions vary in parallel with the electronagativity of R in RCOO~-.     

激光溅射-分子束法研究镁、铝离子与乙腈分子的气相化学反应

利用激光溅射-分子束技术研究了Mg+、 Al+与乙腈分子的气相团簇反应.根据反射式飞行时间质谱检测的结果发现, Mg+、 Al+与乙腈分子反应形成不同尺寸的团簇离子产物,其中Al+与(CHCN)n的结合数n=1～10,而Mg+与(CHCN)n的结合数n=1～5. Al+(CHCN)n、 Mg+(CHCN)n团簇离子产物的强度分布都存在明显的强度间隙现象. Al+与(CHCN)n进行缔合时,出现了两个强度间隙;而Mg+与(CHCN)n进行缔合时,则只存在一个强度间隙. Al+的第一强度间隙在n=4～5,第二强度间隙在n=6～7;而Mg+的强度间隙在n=2～3.     

Mono-silicon isoelectronic replacement in CAl4: van't hoff/le bel carbon or not?

In cluster studies, the isoelectronic replacement strategy has been successfully used to introduce new elements into a known structure while maintaining the desired topology. The well-known penta-atomic 18 valence electron (ve) species and its Al⁻/Si or Al/Si⁺ isoelectronically replaced clusters CAl₃Si⁻, CAl₂Si₂, , and , all possess the same anti-van't Hoff/Le Bel skeletons, that is, nontraditional planar tetracoordinate carbon (ptC) structure. In this article, however, we found that such isoelectronic replacement between Si and Al does not work for the 16ve-CAl₄ with the traditional van't Hoff/Le Bel tetrahedral carbon (thC) and its isoelectronic derivatives CAl₃X (X = Ga/In/Tl). At the level of CCSD(T)/def2-QZVP//B3LYP/def2-QZVP, none of the global minima of the 16ve mono-Si-containing clusters CAl₂SiX⁺ (X = Al/Ga/In/Tl) maintains thC as the parent CAl₄ does. Instead, X = Al/Ga globally favors an unusual ptC structure that has one long C─X distance yet with significant bond index value, and X = In/Tl prefers the planar tricoordinate carbon. The frustrated formation of thC in these clusters is ascribed to the CSi bonding that prefers a planar fashion. Inclusion of chloride ion would further stabilize the ptC of CAl₂SiAl⁺ and CAl₂SiGa⁺. The unexpectedly disclosed CAl₂SiAl⁺ and CAl₂SiGa⁺ represent the first type of 16ve-cationic ptCs with multiple bonds. © 2019 Wiley Periodicals, Inc.