Halogen-hydride interaction between Z-X (Z = CN, NC; X = F, Cl, Br) and H-Mg-Y (Y = H, F, Cl, Br, CH3)

Halogen-hydride interactions between Z-X (Z = CN, NC and X = F, Cl, Br) as halogen donor and H-Mg-Y (Y = H, F, Cl, Br, CH(3)) as electron donor have been investigated through the use of Becke three-parameter hybrid exchange with Lee-Yang-Parr correlation (B3LYP), second-order M?ller-Plesset perturbation theory (MP2), and coupled-cluster single and double excitation (with triple excitations) [CCSD(T)] approaches. Geometry changes during the halogen-hydride interaction are accompanied by a mutual polarization of both partners with some charge transfer occurring from the electron donor subunit. Interaction energies computed at MP2 level vary from -1.23 to -2.99 kJ/mol for Z-F···H-Mg-Y complexes, indicating that the fluorine interactions are relatively very weak but not negligible. Instead, for chlorine- and bromine-containing complexes the interaction energies span from -5.78 to a maximum of -26.42 kJ/mol, which intimate that the interactions are comparable to conventional hydrogen bonding. Moreover, the calculated interaction energy was found to increase in magnitude with increasing positive electrostatic potential on the extension of Z-X bond. Analysis of geometric, vibrational frequency shift and the interaction energies indicates that, depending on the halogen, CN-X···H interactions are about 1.3-2.0 times stronger than NC-X···H interactions in which the halogen bonds to carbon. We also identified a clear dependence of the halogen-hydride bond strength on the electron-donating or -withdrawing effect of the substituent in the H-Mg-Y subunits. Furthermore, the electronic and structural properties of the resulting complexes have been unveiled by means of the atoms in molecules (AIM) and natural bond orbital (NBO) analyses. Finally, several correlative relationships between interaction energies and various properties such as binding distance, frequency shift, molecular electrostatic potential, and intermolecular density at bond critical point have been checked for all studied systems.     

Structures,vibrational spectra,and relative energies of HXSiS (X = H,F, and Cl) isomers

The potential energy surface for the decomposition of HXSiS (X = H, F, and Cl) on the singlet state has been explored by B3LYP and CCSD(T) calculations. Five different types of reaction are proposed: (A) 1,1‐HX elimination, (B) 1,2‐H shift, (C) 1,2‐X shift, (D) H · and XSiS · radical formation, and (E) X · and HSiS · radical formation. These results show interesting trends for the HXSiS isomers. Our theoretical investigations suggest that the doubly bonded species HXSiS should be the lowest energy structure among the isomers from both kinetic and thermodynamic viewpoints. We also report theoretical predictions of molecular parameters and vibrational infrared (IR) spectra of the monohalogen‐substituted silanethione, which should be useful for future experimental observations. © 2001 John Wiley & Sons, Inc. Int J Quant Chem 82: 14–25, 2001     

Study of the interaction in clusters formed by phenol and CH3X (X=CN,F,Cl) molecules

The characteristics of the interaction between phenol and acetonitrile, methyl fluoride and methyl chloride were studied. The most stable structures for clusters containing one or two CH3X molecules and one phenol moiety were located by means of ab initio and density functional theory calculations. Phenol-acetonitrile dimer presents two almost equally stable structures; one of them is a typical linearly hydrogen bonded minimum, whereas in the other one, a C-H...pi contact is established accompanied by a distorted O-H...N hydrogen bond. Although the latter minimum presents the larger interaction energy, deformation effects favor the formation of the linear hydrogen bonded one. In complexes with methyl fluoride and methyl chloride, this arrangement is the most stable structure and no linear hydrogen bonded structures were located. Our best estimates for the interaction energies amount to -27.8, -21.6, and -19.7 kJ/mol for clusters of phenol with acetonitrile, methyl fluoride, and methyl chloride, respectively. The main contribution to the stabilization of these clusters is of electrostatic nature, although in structures where a C-H...pi contact is present, the dispersion contribution is also significant. In clusters formed by phenol and two CH3X units, the most stable arrangement corresponds to a head to tail disposal with O-H...X, C-H...X, and C-H...pi contacts forming a cycle. Only for this type of arrangement, three body effects are non-negligible even though they constitute a minor effect. The results also indicate that interactions with methyl fluoride and methyl chloride are of similar intensity, although weaker than with acetonitrile. Significant frequency shifts are predicted for the O-H stretching, which increase when increasing the number of CH3X molecules.     

Theoretical investigation of the relative stabilities of XSSX and X2SS isomers (X = F,Cl, H,and CH3)

The structures and relative stabilities of a series of disulfide (XSSX) and thiosulfoxide (X₂SS) isomers have been studied for X = F, Cl, CH₃, and H, using various levels of conventional ab initio and density functional theory (DFT). The XSSX isomers are more stable than the X₂SS isomers for all substituents. The energy gap ΔE(X) between the two isomers increases (i.e., XSSX becomes more stable with respect to X₂SS), and the S? S bond contracts in the series for X = F, Cl, CH₃, H. The results are interpreted by means of natural population analysis (NPA) (e.g., the interaction between the disulfide moiety S and the two substituents X·). The bonding in the hypervalent X₂SS species is similar to the bonding in the nonhypervalent XSSX and does not involve a special role for sulfur-3d orbitals. These orbitals acquire only minimal populations and are not to be conceived as valence orbitals. The DFT and conventional ab initio results, Xα/DZP and MP2/6-31G** optimized structures and isomerization energies (at the highest levels of both methods), agree well. © 1995 by John Wiley & Sons, Inc.     

Theoretical study and rate constants calculation for the reactions X + CF3CH2OCF3 (X = F,Cl, Br)

The multiple‐channel reactions X + CF₃CH₂OCF₃ (X = F, Cl, Br) are theoretically investigated. The minimum energy paths (MEP) are calculated at the MP2/6‐31+G(d,p) level, and energetic information is further refined by the MC‐QCISD (single‐point) method. The rate constants for major reaction channels are calculated by canonical variational transition state theory (CVT) with small‐curvature tunneling (SCT) correction over the temperature range 200–2000 K. The theoretical three‐parameter expressions for the three channels k_1a(T) = 1.24 × 10^?15T^1.24exp(?304.81/T), k_2a(T) = 7.27 × 10^?15T^0.37exp(?630.69/T), and k_3a(T) = 2.84 × 10^?19T^2.51 exp(?2725.17/T) cm³ molecule^?1 s^?1 are given. Our calculations indicate that hydrogen abstraction channel is only feasible channel due to the smaller barrier height among five channels considered. © 2011 Wiley Periodicals, Inc. J Comput Chem, 2012     

Unimolecular rate constants for HX or DX elimination (X = F, Cl) from chemically activated CF3CH2CH2Cl, C2H5CH2Cl, and C2D5CH2Cl: threshold energies for HF and HCl elimination

Vibrationally activated CF(3)CH(2)CH(2)Cl molecules were prepared with 94 kcal mol(-1) of vibrational energy by the combination of CF(3)CH(2) and CH(2)Cl radicals and with 101 kcal mol(-1) of energy by the combination of CF(3) and CH(2)CH(2)Cl radicals at room temperature. The unimolecular rate constants for elimination of HCl from CF(3)CH(2)CH(2)Cl were 1.2 x 10(7) and 0.24 x 10(7) s(-1) with 101 and 94 kcal mol(-1), respectively. The product branching ratio, k(HCl)/k(HF), was 80 +/- 25. Activated CH(3)CH(2)CH(2)Cl and CD(3)CD(2)CH(2)Cl molecules with 90 kcal mol(-1) of energy were prepared by recombination of C(2)H(5) (or C(2)D(5)) radicals with CH(2)Cl radicals. The unimolecular rate constant for HCl elimination was 8.7 x 10(7) s(-1), and the kinetic isotope effect was 4.0. Unified transition-state models obtained from density-functional theory calculations, with treatment of torsions as hindered internal rotors for the molecules and the transition states, were employed in the calculation of the RRKM rate constants for CF(3)CH(2)CH(2)Cl and CH(3)CH(2)CH(2)Cl. Fitting the calculated rate constants from RRKM theory to the experimental values provided threshold energies, E(0), of 58 and 71 kcal mol(-1) for the elimination of HCl or HF, respectively, from CF(3)CH(2)CH(2)Cl and 54 kcal mol(-1) for HCl elimination from CH(3)CH(2)CH(2)Cl. Using the hindered-rotor model, threshold energies for HF elimination also were reassigned from previously published chemical activation data for CF(3)CH(2)CH(3,) CF(3)CH(2)CF(3), CH(3)CH(2)CH(2)F, CH(3)CHFCH(3), and CH(3)CF(2)CH(3). In an appendix, the method used to assign threshold energies was tested and verified using the combined thermal and chemical activation data for C(2)H(5)Cl, C(2)H(5)F, and CH(3)CF(3).     

Schwingungsspektren der Vinylmethylhalosilane H2C = CH(CH3)3−nSiXn (n = 1,2; X = F,Cl)

Ohne Zusammenfassung     

Reaction mechanism of HSH and CH3SH with NH2CH2COCH2X (X = F and Cl) molecules

The reaction mechanism of model compounds H₂S and CH₃SH for cysteine proteases with NH₂CH₂COCH₂X (X = F and Cl) molecules has been investigated using DFT methods with B3LYP and B3PW91 hybrid density functionals at 6‐31+G* basis sets. The single point energy has been calculated for the above reactions with B3LYP and B3PW91 functionals using aug‐cc‐PVDZ infinite basis set in both gas and solution phases. The intrinsic reaction coordinates calculations have been performed to confirm that each transition state is linked by the desired reactants and products. The geometries and relative energies for various stationary points have been determined and discussed. The zero point vibrational energy corrections have been made to predict the reliable energy. The negative value of reaction energy indicates that the overall reaction profile is found to be exothermic. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008     

钠卤类硅烯的结构与稳定性

本文用RHF/STO-3G解析梯度方法研究了钠卤类硅烯H2SiNaX(X=F,Cl)势能面的主要特征, 得到了它们的几种平衡构型及其异构化的过渡态构型。与锂卤类硅烯相似, 三元环构型和P-配合物构型是最稳定的构型; 其它的两种构型-σ-配合物和经典"四面体", 也是势能面上的极值点, 但能量相对较高, 不稳定。文中对各构型的特点进行了分析。     

Synthesis and spectroscopy of N3P3X5OCH=CH2 (X = Cl, F, OCH3, OCH2CF3, N(CH3)2) and N3P3X4(OCH=CH2)2 (X = Cl, N(CH3)2). Correlations of ultraviolet photoelectron spectroscopy and nuclear magnetic resonance data to electronic and geometrical structure

The syntheses of the vinyloxycyclotriphosphazene derivatives N3P3X5OCH=CH2 (X = OMe, OCH2CF3) and the N3P3(NMe2)4(OCH=CH2)2 isomeric mixture along with improved preparations of N3P3X5OCH=CH2 (X = F, NMe2) are reported. The interactions between the vinyloxy function and the cyclophosphazene in these and the previously reported N3P3Cl5 (OCH=CH2) and N3P3F6-n(OCH=CH2)n (n = 1-4) have been examined by ultraviolet photoelectron spectroscopy (UPS) and NMR spectroscopy. The UPS data for the chloro and fluoro derivatives show a strong electron-withdrawing effect of the phosphazene on the olefin that is mediated with decreasing halogen substitution. The 1H and 13C NMR data for N3P3X5OCH=CH2 (X = F, Cl, OMe, OCH2CF3, NMe2) show significant changes as a function of the phosphazene substituent. There is a linear correlation between the beta-carbon chemical shift on the vinyloxy unit and the phosphorus chemical shift at the vinyloxyphosphorus centers. The chemical shifts of the different phosphorus centers on each ring are also related in a linear fashion. These relationships may be understood in terms of the relative electron donor-acceptor abilities of the substituents on the phosphazene ring. The 1H NMR spectra of the N3P3(NMe2)4(OCH-CH2)2 isomeric mixture allow for assignment of the relative amounts of cis and trans isomers. A model for the observed cis preference in the formation of N3P3Cl4(OCH=CH)2 is presented.     

Near-thermal reactions of Au(+)(1S,3D) with CH3X (X = F,Cl)

Reactions of Au(+)((1)S) and Au(+)((3)D) with CH(3)F and CH(3)Cl have been carried out in a drift cell in He at a pressure of 3.5 Torr at both room temperature and reduced temperatures in order to explore the influence of the electronic state of the metal on reaction outcomes. State-specific product channels and overall two-body rate constants were identified using electronic state chromatography. These results indicate that Au(+)((1)S) reacts to yield an association product in addition to AuCH(2)(+) in parallel steps with both neutrals. Product distributions for association vs HX elimination were determined to be 79% association/21% HX elimination for X = F and 50% association/50% HX elimination when X = Cl. Reaction of Au(+)((3)D) with CH(3)F also results in HF elimination, which in this case is thought to produce (3)AuCH(2)(+). With CH(3)Cl, Au(+)((3)D) reacts to form AuCH(3)(+) and CH(3)Cl(+) in parallel steps. An additional product channel initiated by Au(+)((3)D) is also observed with both methyl halides, which yields CH(2)X(+) as a higher-order product. Kinetic measurements indicate that the reaction efficiency for both Au(+) states is significantly greater with CH(3)Cl than with CH(3)F. The observed two-body rate constant for depletion of Au(+)((1)S) by CH(3)F represents less than 5% of the limiting rate constant predicted by the average dipole orientation model (ADO) at room temperature and 226 K, whereas CH(3)Cl reacts with Au(+)((1)S) at the ADO limit at both room temperature and 218 K. Rate constants for depletion of Au(+)((3)D) by CH(3)F and CH(3)Cl were measured at 226 and 218 K respectively, and indicate that Au(+)((3)D) is consumed at approximately 2% of the ADO limit by CH(3)F and 69% of the ADO limit by CH(3)Cl. Product formation and overall efficiency for all four reactions are consistent with previous experimental results and available theoretical models.     

Model identity SN2 reactions CH3X + X- (X = F, Cl, CN, OH, SH, NH2, PH2): Marcus theory analyzed

The structures of seven gas phase identity S(N)2 reactions of the form CH(3)X + X(-) have been characterized with seven distinct theoretical methods: RHF, B3LYP, BLYP, BP86, MP2, CCSD, and CCSD(T), in conjunction with basis sets of double and triple zeta quality. Additionally, the energetics of said reactions have been definitively computed using focal point analyses utilizing extrapolation to the one-particle limit for the Hartree-Fock and MP2 energies using basis sets of up to aug-cc-pV5Z quality, inclusion of higher order correlation effects [CCSD and CCSD(T)] with basis sets of aug-cc-pVTZ quality, and additional auxiliary terms for core correlation and scalar relativistic effects. Final net activation barriers for the reactions are E(b)(F,F)= -0.8, E(b)(Cl,Cl)= 1.6, E(b)(CN,CN)= 28.7, E(b)(OH,OH)= 14.3, E(b)(SH,SH)= 13.8, E(b)(NH2,NH2)= 28.6, and E(b)(PH2,PH2)= 25.7 kcal mol(-1). General trends in the energetics, specifically the performance of the density functionals, and the component energies of the focal point analyses are discussed. The utility of classic Marcus theory as a technique for barrier predictions has been carefully analyzed. The standard Marcus theory results show disparities of up to 9 kcal mol(-1) with respect to explicitly computed results. However, when alternative approaches to Marcus theory, independent of the well-depths, are considered, excellent performance is achieved, with the largest deviations being under 3 kcal mol(-1).     

CH2X(X=H,F,Cl)与臭氧反应机理的量子化学研究

用量子化学UMP2方法,在6-311++G**基组水平上研究了CH2X(X=H,F,Cl)与臭氧反应机理,全参数优化了反应过程中反应物、中间体、过渡态和产物的几何构型,在UQCISD(T)/6-311++G**水平上计算了它们的能量,并对它们进行了振动分析,以确定中间体和过渡态的真实性.从CH2X(X=H,F,Cl)与O3的反应机理的研究结果看,它们与O3反应的活性都比较强,相对而言,活性大小顺序为CH2F＞CH3＞CH2Cl,也就是说,CH2F自由基与臭氧间的反应活性最强,对大气臭氧的损耗将是最大的.同时研究还发现CH2X(X=H,F,Cl)系列自由基与O3的反应都是强放热反应.     

Structures, energies, and spin-spin coupling constants of methyl-substituted 1,3-diborata-2,4-diphosphoniocyclobutanes: four-member B-P-B-P rings B2P2(CH3)(n)H(8-n), with n = 0, 1, 2, 4

An ab initio study has been carried out to determine the structures, relative stabilities, and spin-spin coupling constants of a set of 17 methyl-substituted 1,3-diborata-2,4-diphosphoniocyclobutanes B(2)P(2)(CH(3))(n)H(8-n), for n = 0, 1, 2, 4, with four-member B-P-B-P rings. The B-P-B-P rings are puckered in a butterfly conformation, in agreement with experimental data for related molecules. Isomers with the CH(3) group bonded to P are more stable than those with CH(3) bonded to B. If there is only one methyl group or if two methyl groups are bonded to two different P or B atoms, isomers with equatorial bonds are more stable than those with axial bonds. However, when two methyl groups are present, the gem isomers are the most stable for molecules B(2)P(2)(CH(3))(2)H(6) with P-C and B-C bonds, respectively. Transition structures present barriers to the interconversion of two equilibrium structures or to the interchange of axial and equatorial positions in the same isomer. These barriers are very low for the isomer with two methyl groups bonded to B in axial positions for the isomer with four axial bonds and for the isomer with geminal B-C bonds at both B atoms. Coupling constants (1)J(B-P), (1)J(P-C), (1)J(B-C), (2)J(P-P), and (3)J(P-C) are capable of providing structural information. They are sensitive to the number of methyl groups present and can discriminate between axial, equatorial, and geminal bonds, although not all do this to the same extent. The one-bond coupling constants (1)J(B-P), (1)J(P-C), and (1)J(B-C) are similar in equilibrium and transition structures, but (3)J(P-C) and (2)J(P-P) are not. These coupling constants and those of the corresponding fluoro-derivatives of the 1,3-diborata-2,4-diphosphoniocyclobutanes demonstrate the great sensitivity of phosphorus coupling to structural and electronic effects.     

Definitive ab initio studies of model SN2 reactions CH(3)X+F- (X=F,Cl, CN,OH, SH,NH(2), PH(2))

The energetics of the stationary points of the gas-phase reactions CH(3)X+F(-)-->CH(3)F+X(-) (X=F, Cl, CN, OH, SH, NH(2) and PH(2)) have been definitively computed using focal point analyses. These analyses entailed extrapolation to the one-particle limit for the Hartree-Fock and MP2 energies using basis sets of up to aug-cc-pV5Z quality, inclusion of higher-order electron correlation [CCSD and CCSD(T)] with basis sets of aug-cc-pVTZ quality, and addition of auxiliary terms for core correlation and scalar relativistic effects. The final net activation barriers for the forward reactions are: E (b/F,F)=-0.8, E (b/F, Cl)=-12.2, E (b/F,OH)=+13.6, E b/F,OH=+16.1, E b/F,SH=+2.8, Eb/F, NH=+32.8, and E b/F,PH =+19.7 kcal x mol(-1). For the reverse reactions E b/F,F= -0.8, Eb/Cl,F =+18.3, E b/CN,F=+12.2, E b/OH,F =-1.8, E b/SH,F =+13.2, E b/NH(2),=-1.5, and E b/PH(2) =+9.6 kcal x mol(-1). The change in energetics between the CCSD(T)/aug-cc-pVTZ reference prediction and the final extrapolated focal point value is generally 0.5-1.0 kcal mol(-1). The inclusion of a tight d function in the basis sets for second-row atoms, that is, utilizing the aug-cc-pV(X+d)Z series, appears to change the relative energies by only 0.2 kcal x mol(-1). Additionally, several decomposition schemes have been utilized to partition the ion-molecule complexation energies, namely the Morokuma-Kitaura (MK), reduced variational space (RVS), and symmetry adapted perturbation theory (SAPT) techniques. The reactant complexes fall into two groups, mostly electrostatic complexes (FCH(3).F(-) and ClCH(3).F(-)), and those with substantial covalent character (NCCH(3).F(-), CH(3)OH.F(-), CH(3)SH.F(-), CH(3)NH(2).F(-) and CH(3)PH(2).F(-)). All of the product complexes are of the form FCH(3).X(-) and are primarily electrostatic.     

Remote substituent effects on N-X (X = H,F, Cl,CH3, Li) bond dissociation energies in para-substituted anilines

UB3LYP/6-311++g**//UB3LYP/6-31+g* and ROMP2/6-311++g**//UB3LYP/6-31+g* methods were used to calculate (i) N-X bond dissociation energies (BDE) in 4-YC6H4NH-X and (ii) N-H BDEs in 4-YC6H4NU-H, where Y = H, Me, OCH3, SMe, NH2, NMe2, SiMe3, F, Cl, CN, COOH, CF3, and NO2, X = H, CH3, F, Cl, and Li, and U = H, F, and CH(3). It was found that N-H BDEs of 4-YC6H4NH2 have a positive correlation with the substituent sigma(p+) constants. The slope (rho+) is about 3.0-4.3 kcal/mol, which is in good agreement with the experimental results. It was also found that the substituent effects on N-X BDEs of 4-YC6H4NH-X change considerably when X changes. rho(+)values for N-CH3, N-F, N-Cl, and N-Li BDEs were calculated to be 3.1-4.6, 1.3-1.9, 1.8-2.6, and 4.9-6.8 kcal/mol, respectively. The reason for the variation of substituent effects was proposed to be the ground-state effect, i.e., the interaction between the intact NH-X moiety and the parasubstituents. Finally, alpha-substitution was found to be able to significantly change the substituent effects. rho(+)values for N-H BDEs of 4-C6H4NCH3(-)H and 4-C6H4NF-H are 2.5-4.0 and 1.7-1.9 kcal/mol, respectively.     

Structures, energies, and spin-spin coupling constants of fluoro-substituted 1,3-diborata-2,4-diphosphoniocyclobutanes: four-member B-P-B-P rings B2P2F(n)H(8-n) with n = 0, 1, 2, 4

An ab initio study has been carried out to determine the structures, relative stabilities, and spin-spin coupling constants of a set of 15 fluoro-substituted 1,3-diborata-2,4-diphosphoniocyclobutanes B(2)P(2)F(n)H(8-n), for n = 0, 1, 2, 4, with four-member B-P-B-P rings. Except for B(2)P(2)F(4)H(4) with four fluorines bonded to two borons, these rings are puckered in a butterfly conformation. For a fixed number of fluorines, the isomers with B-F bonds are significantly more stable than those with P-F bonds. As the number of fluorines increases, the energy difference between the most stable isomer and the other isomers increases. Transition structures which interconvert axial and equatorial positions present relatively small inversion barriers. Coupling constants involving (31)P, namely, (1)J(B-P), (1)J(P-F), (2)J(P-P), (2)J(P-F), and (3)J(P-F) are large and are capable of providing structural information. They are sensitive to the number of fluorines present and can discriminate between axial, equatorial, and geminal B-F and P-F bonds, although not all do this to the same extent. (1)J(B-P) and (2)J(P-P) are similar in equilibrium and transition structures. Although transition structures no longer discriminate between axial and equatorial bonds, (1)J(P-F) and (3)J(P-F) remain sensitive to the number of fluorine atoms present.     

Singlet-triplet splittings and ground- and excited-state electron affinities of selected cyanosilylenes, XSiCN (X = H, F, Cl, CH3, SiH3, CN)

Several cyanosilylenes, XSiCN, (X = H, F, Cl, CH3, SiH3, CN) have been investigated using the RHF-ACPF and CAS(2,2)-ACPF methods in conjunction with the aug-cc-pVTZ basis sets. All silylenes are found to have singlet ground states. The ground-state electron affinities are found to be rather high, i.e., 1.832, 1.497, 1.896, 1.492, 2.235, and 2.631 eV for HSiCN, FSiCN, ClSiCN, H3CSiCN, H3SiSiCN, and Si(CN)2, respectively. The existence of bound excited negative ion states has been discovered for the first time within these silylenes. All these bound excited anion states belong to the totally symmetric irreducible representations and can be characterized as dipole-bound negative ion states. All triplet excited states have even larger dipole moments than the singlet states and are, therefore, "dressed" by dipole-bound negative ion states, which correspond to Feshbach resonances.     

Molecular orbital investigation of the protonated H2X2AlNHn(CH3)3-n+ (X = F, Cl, and Br; n = 0-3) complexes

Structures of protonated alane-Lewis base donor-acceptor complexes H2X2AlNHn(CH3)(3-n)+ (X = F, Cl, and Br; n = 0-3) as well as their neutral parents were investigated. All the monocations H2X2AlNHn(CH3)(3-n)+ are Al-H protonated involving hypercoordinated alane with a three-center two-electron bond and adopt the C(s) symmetry arrangement. The energetic results show that the protonated alane-Lewis complexes are more stable than the neutral ones. They also show that this stability decreases on descending in the corresponding periodic table column from fluorine to bromine atoms. The calculated protonation energies of HX2AlNHn(CH3)(3-n) to form H2X2AlNHn(CH3)(3-n)+ were found to be highly exothermic. The possible dissociation of the cations H2X2AlNHn(CH3)(3-n)+ into X2AlNHn(CH3)(3-n)+ and molecular H2 is calculated to be endothermic.