Full valence complete active space SCF, multireference CI, and density functional calculations of 1A1—3B1 singlet—triplet gaps for the valence-isoelectronic series BH-2, CH2, NH+2, AlH-2, SiH2, PH+2, GaH-2, GeH2, and AsH+2

Electron collisions with the BH2radical using theR-matrix method

“…However, such a pole has been found in the 3 B 1 scattering symmetry with a vertical electron affinity of 0.142 eV, corresponding to a bound state of the anion BH − 2 with the 3 B 1 symmetry, which agrees very well with the theoretical (adiabatic) result 0.16 eV [19]. The previous theoretical studies [19,20] predict BH 2 bound anions with both 1 A 1 and 3 B 1 symmetry, with a B-H bond of about 1.2Å and H-B-H angles of about 102 • and 126 • , respectively. Since the present R-matrix calculations use the BH 2 equilibrium geometry with a much larger H-B-H angle than 102 • , it is not surprising that no R-matrix pole with 1 A 1 scattering symmetry was found.…”

THE STUDY OF THE PROPERTIES OF THE GROUND- AND LOW-LYING EXCITED STATES OF ASH2, ${\rm ASH}_{2}^{+}$ AND ${\rm ASH}_{2}^{-}$

“…The geometries are calculated at cc-pVTZ and cc-pVQZ level, respectively. Cramer et al 16 have researched some electronic states of AsH þ 2 with the MRCISD (Q)/CASSCF method, and our calculated results at the SAC/SAC-CI method are close to the results of MRCISD(Q)/CASSCF method. The equilibrium geometry of 1 1 B 1 state are R AsH ¼ 1:514 A and HAsH ¼ 123:14 at SAC-CI/cc-pVTZ method, and the corresponding values are R AsH ¼ 1:512 A and HAsH ¼ 123:13 at SAC-CI/ cc-pVQZ method, respectively, and the corresponding values are R AsH ¼ 1:526 A and HAsH ¼ 122:2 at CASSCF/SOCI 10 method, respectively.…”

“…15 In 1994, Cramer obtained the geometries for the valence-isoelectronic series of AsH þ 2 . 16 In 1998, Saito and coworkers observed the rotational spectra of AsH 2 and AsD 2 using rotational spectroscopy at the millimeter wavelengths and derived the equilibrium geometries of the ground state. 17À19 In 2005, Mintz and Wilson optimized the ground states of AsH 2 and AsH þ 2 by coupled cluster theory with singles, doubles and quasiperturbative triple excitations (CCSD(T)) method with a variety of basis sets.…”

Nitrenium Ions and Problem of Direct Electrophilic Amination of Aromatic Compounds

“…Up to now, quantum-chemical calculations were performed for a wide variety of nitrenium ions: NH 2 + [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40], MeNH + [22,24,25,30,36,41], Me 2 N + [22,24,25,30,41], MeAcN + [22], (CH 2 ) 2 N + [42], (CH 2 ) 4 N + , (CH 2 ) 5 N + [22,24,25], (XCH=CH)MeN + (X = H, Cl) [25], (CH) 2 N + , CHN 2 + [43], (CH) 6 N + [44], XN 3 + (X = O, S, Se, Te) [45], XNH + (X = NH 2 , PH 2 , OR, SH, Cl, F, Br, I, CN, NC 2 ) [23,27,28,32,34,36,40,46], X(CHO)N + [X = N, NH 2 , PH 2 , OR, SH, Ph(CH 2 ) n O] …”

“…Unsubstituted nitrenium ion H 2 N + (3) exists mainly in the triplet state, and the energy difference between the singlet and triplet states was estimated at 89-152 kJ/mol [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40]. The best agreement with the experimental value (∆E ST = 125.9 kJ/mol [88]) was obtained by ab initio calculations (∆E ST = 125.8 kJ/mol, CASSCF-MRCI + ZPVE; ∆E ST = 125.6 kJ/mol, TZ2P(f,d)CASSCF(6,6)-SOCI + ZPVE [33] 149.4°0 .1025 nm 475 calculations [MP4(SDTQ)/6-311 + G(3d2f,2p)// MP2/6-311 + G(3d,2p)] showed that both singlet and triplet states of H 2 N + ion have an angular structure and that the HNH angle in the triplet state is considerably greater [24].…”