1. catena-Poly[[bis-(2,4-dichloro-benzoato)bis-(methanol-κO)cobalt(II)]-μ-4,4'-bipyridine-κN:N']
Min Young Hyun, Pan-Gi Kim, Cheal Kim, Youngmee Kim Acta Crystallogr Sect E Struct Rep Online. 2011 Dec 1;67(Pt 12):m1705. doi: 10.1107/S1600536811046149. Epub 2011 Nov 9.
In the title compound, [Co(C(7)H(3)Cl(2)O(2))(2)(C(10)H(8)N(2))(CH(3)OH)(2)](n), the Co(II) ion lies on a twofold rotation axis and is in a slightly distorted octa-hedral CdO(4)N(2) environment, formed by two O atoms from monodentate dichloro-benzoate ligands, two O atoms from methanol ligands, and two N atoms from trans-related 4,4'-bipyridine ligands. The bipyridine ligands also lies on a twofold rotation axis and bridge the Co(II) ions, forming chains extending along [010]. An intra-chain O-H⋯O hydrogen bond is observed.
2. Photochemical Alkene Hydrophosphination with Bis(trichlorosilyl)phosphine
Michael B Geeson, Keita Tanaka, Rachid Taakili, Rachid Benhida, Christopher C Cummins J Am Chem Soc. 2022 Aug 17;144(32):14452-14457. doi: 10.1021/jacs.2c05248. Epub 2022 Aug 4.
Bis(trichlorosilyl)phosphine (HP(SiCl3)2, 1) was prepared from [TBA][P(SiCl3)2] ([TBA]2, TBA = tetra-n-butylammonium) and triflic acid in 36% yield. Phosphine 1 is an efficient reagent for hydrophosphination of unactivated terminal olefins under UV irradiation (15-60 min) and gives rise to bis(trichlorosilyl)alkylphosphines (RP(SiCl3)2, R = (CH2)5CH3, 88%; (CH2)7CH3, 98%; (CH2)2C(CH3)3, 76%; CH2Cy, 93%; (CH2)2Cy, 95%; CH2CH(CH3)(CH2)2CH3, 82%; (CH2)3O(CH2)3CH3, 95%; (CH2)3Cl, 83%; (CH2)2SiMe3, 92%; (CH2)5C(H)CH2, 44%) in excellent yields. The products require no further purification beyond filtration and removal of volatile material under reduced pressure. The P-Si bonds of prototypical products RP(SiCl3)2 (R = -(CH2)5CH3, -(CH2)7CH3) are readily functionalized to give further phosphorus-containing products: H3C(CH2)7PCl2 (56%), [H3C(CH2)5P(CH2Ph)3]Br (84%), H3C(CH2)7PH2 (61%), H3C(CH2)5P(O)(H)(OH) (81%), and H3C(CH2)5P(O)(OH)2 (55%). Experimental mechanistic investigations, accompanied by quantum chemical calculations, point toward a radical-chain mechanism. Phosphine 1 enables the fast, high-yielding, and atom-efficient preparation of compounds that contain phosphorus-carbon bonds in procedures that bypass white phosphorus (P4), a toxic and high-energy intermediate of the phosphorus industry.
3. Benchmark ab Initio Characterization of the Inversion and Retention Pathways of the OH- + CH3Y [Y = F, Cl, Br, I] SN2 Reactions
Domonkos A Tasi, Zita Fábián, Gábor Czakó J Phys Chem A. 2018 Jul 5;122(26):5773-5780. doi: 10.1021/acs.jpca.8b04218. Epub 2018 Jun 21.
We study the Walden-inversion, front-side attack retention, and double-inversion retention pathways of the OH- + CH3Y [Y = F, Cl, Br, I] SN2 reactions using high-level ab initio methods. Benchmark stationary-point structures and frequencies are computed at the CCSD(T)-F12b/aug-cc-pVTZ level of theory and the best technically feasible relative energies are determined on the basis of CCSD(T)-F12b/aug-cc-pVQZ computations complemented with post-CCSD(T) correlation effects at the CCSDT(Q)/aug-cc-pVDZ level, core correlation corrections at the CCSD(T)/aug-cc-pwCVTZ level, scalar relativistic effects using effective core potentials for Br and I, and zero-point energy corrections at the CCSD(T)-F12b/aug-cc-pVTZ level. Walden inversion proceeds via hydrogen-bonded HO-···HCH2Y (Cl, Br, I) complex → hydrogen-bonded HO-···HCH2Y (Cl, Br, I) transition state → ion-dipole HO-···H3CY (F, Cl, Br) complex → Walden-inversion [HO-CH3-Y]- (F, Cl, Br) transition state → hydrogen-bonded CH3OH···Y- (F, Cl, Br, I) complex, where the Y-dependent existence of the submerged stationary points is indicated in parentheses. Front-side HO-···YCH3 (Cl, Br, I) complexes are also found and HO-···ICH3 is a deeper minimum than HO-···HCH2I. Front-side attacks go over high barriers of 42.8 (F), 28.7 (Cl), 22.4 (Br), and 17.2 (I) kcal/mol, well above the double-inversion barrier heights of 16.7 (F), 3.4 (Cl), 1.1 (Br), and -3.7 (I) kcal/mol.
