Sterically Congested 5-Diphenylphosphinoacenaphth-6-yl-silanes and -silanols

Abstract

The synthesis and characterization of the 5-diphenylphosphinoacenaphth-6-yl-silanes 5-Ph 2 P-Ace-6-SiMe 2 H (1), 5-Ph 2 P(S)-Ace-6-SiMe 2 H (1S), 5-Ph 2 P(Se)-Ace-6-SiMe 2 H (1Se), and 5-Ph 2 P-Ace-6-SiMe 2 Cl (2) as well as of the 5-diphenylphosphinoacenaphth-6-yl-silanols 5-Ph 2 P-Ace-6-SiMe 2 OH (3), 5-Ph 2 P(O)-Ace-6-SiMe 2 OH (3O), 5-Ph 2 P(S)-Ace-6-SiMe 2 OH (3S), and 5-Ph 2 P(Se)-Ace-6-SiMe 2 OH (3Se) are reported. Due to steric congestion in the bay area, the substituents in peri-positions are affected by repulsion, out-of-plane deflection, and distortion of the spatial arrangement to various extents. The peri-interaction energy associated with the steric congestion of these and a number of previously known reference compounds was computationally estimated with a set of isodesmic reactions. The organo-H-silanes 1, 1S, and 1Se possess very weak intramolecular hydrogen bridges of the types Si−H···P and Si−H···EP (E = S, Se), whereas the organosilanols 3O, 3S, and 3Se contain medium-strength hydrogen bonds of the type Si−OH···EP (E = O, S, Se). These hydrogen bonds and those of related model complexes H 3 SiOH···(E)PH 3 were analyzed applying real-space bonding indicators derived from the electron and pair densities using the atoms-in-molecules and electron localizability indicator space-partitioning schemes as well as natural population analysis and natural bond orbital analyses.

Insights into Frustrated and Regular peri‐Substituted (Ace‐)Naphthylaminoboranes and (Ace‐)Naphthylphosphinoboranes

“…As anticipated, all five natural FLP conformers ( 4–6 , 9 , 11 ) give rise to positive α‐PIE values, ranging from 12.9 kJ mol –1 for 9 to 33.2 kJ mol –1 for 4 . The latter value is very close to that reported for 1,8‐(Ph 2 P) 2 Nap (31.5 kJ mol –1 ) . The unobserved FLP conformers 8′ , 8′′ , 9′ , and 11′ constantly showed higher α‐PIE values than the natural conformers 8 , 9 , and 11 , providing a rational explanation as to why the former conformers are not observed.…”

“…This work aims at extending the range of synthetically available peri ‐substituted (ace‐)naphthylphosphinoboranes to a number of functionalized compounds 5‐Ph 2 P‐Ace‐6‐BRR′ ( 13 , R = R′ = H; 14 , R = H, R′ = C 6 F 5 15 , R = Cl, R′ = C 6 F 5 ; 16 , R = R′ = C 6 F 5 ) possessing regular LP structures. In an effort to quantify the peri ‐interaction energy (α‐PIE) associated with repulsion and attraction of the peri substituents in the 1,8 and 5,6 positions of the naphthalene and acenaphthene derivatives, respectively, isodesmic reactions involving the disubstituted compounds AB, the unsubstituted parent compounds HH, as well as the two monosubstituted compounds AH and BH, were calculated for 1 – 16 (Scheme ) . The peri ‐interaction energy is defined as the energy difference between AB and HH ( E 1 ), on one hand, and AH and BH ( E 2 ), on the other.…”

Mapping the Trajectory of Nucleophilic Substitution at Silicon Using aperi‐Substituted Acenaphthyl Scaffold

“…The J ( 31 P, 29 Si) coupling in 1 is smaller than that of the silane 5‐Ph 2 P‐Ace‐6‐SiMe 2 H ( J= 12.0 Hz), which can be explained by weakening of the σ(Si−H) bond due to the P lone‐pair interaction in the silane. Notably, in the directly related chlorosilane 5‐Ph 2 P‐Ace‐6‐SiMe 2 Cl, no J ( 31 P, 29 Si) coupling has been observed . However, the J ( 19 F, 31 P) couplings of 1 and 1‐Ph 2 P‐C 6 H 4 ‐2‐Me 2 SiF show similar values of J= 22.4 and 28.3 Hz, respectively, which is further evidence of a through‐space interaction between P and Si in 1 because the coupling constant is too large for pure 5 J coupling.…”

“…No J ( 31 P, 29 Si) coupling constants have been reported in 1‐Ph 2 P‐Nap‐8‐SiMe(SiMePh 2 )F for the Si atom in the peri ‐position . The J ( 31 P, 29 Si) coupling in 1 is smaller than that of the silane 5‐Ph 2 P‐Ace‐6‐SiMe 2 H ( J= 12.0 Hz), which can be explained by weakening of the σ(Si−H) bond due to the P lone‐pair interaction in the silane. Notably, in the directly related chlorosilane 5‐Ph 2 P‐Ace‐6‐SiMe 2 Cl, no J ( 31 P, 29 Si) coupling has been observed .…”

A Monoaryllead Trichloride That Resists Reductive Elimination

“…[22] Thel onger life span of 2 under ambient conditions compared to PhPbCl 3 suggests that the intramolecular Pb···O donor-acceptor interaction provides significant kinetic stabilisation, which raises questions regarding the nature of this bond. [23] The a-PIE of 2 (À2.4 KJ mol À1 )i s only very small;s ignificantly smaller than that of RTeCl 3 (À36.0 KJ mol À1 ). [23] The a-PIE of 2 (À2.4 KJ mol À1 )i s only very small;s ignificantly smaller than that of RTeCl 3 (À36.0 KJ mol À1 ).…”