Syntheses, characterisations and X-ray crystal structures of 5,5′-bis(diphenylphosphino)2,2′-bithiophene derivatives, Ph₂(X)P(C₄H₂S)₂P(X)Ph₂(X = O, S and CH₃⁺ · I⁻)

Abstract

Phosphine-substituted oligothiophenes are interesting third-order nonlinear materials. Both their linear and nonlinear optical properties can be altered by varying the group attached to the nonbonding pair of electrons on the phosphorus atoms, the number of phosphine groups attached to the oligothiophene and the number of repeat units in the oligothiophene. In this article, we report the syntheses, multinuclear NMR spectroscopic characterizations and X-ray crystal structures for three derivatives of 5,5 0 -bis(diphenylphosphino)-2,2 0 -bithiophene, Ph 2 (X)P(C 4 H 2 S) 2 P(X)Ph 2 (X ¼ -, 1) in which X is O (2), S (3) and CH 3 þ Á I 7 (4). The X-ray crystal structures exhibit significantly different p-p stacking, suggesting that these compounds could have significantly different nonlinear optical properties in the solid state.

Synthesis, Linear, and Nonlinear Optical Properties of Phosphonato‐Substituted Bithiophenes Derived from 2,2‐Dimethyl‐1,3‐propanediol

“…In each series, the 31 P{ 1 H} NMR resonance shifts in the order Se > S >> O. This trend is not consistent with the electronegativities of the chalcogens (O > S > Se) and is different from that previously reported for bithiophenes with chalcogenodiphenylphosphino substituents (S > Se ≥ O) , , . These different trends indicate that there is no simple correlation between the chemical shifts 31 P{ 1 H} NMR resonances with chalcogen electronegativity and that the effect of the chalcogen on the phosphorus shielding environment is extremely sensitive to the other groups attached to the phosphorus .…”

“…In the X‐ray crystal structures of oligothiophenes with either chalcogenodiphenylphosphine or chalcogenophosphonate substituents derived from 2,2′‐biphenol, this torsion angle varies as the chalcogen is changed, crystallization conditions are changed and the oligothiophene is changed. This torsion angle is also observed to be different for two independent molecules of the same compound . For the bithiophenes that are monosubstituted with chalcogenophosphonates in this study, the X–P–C1–S1 torsion angles are anti‐periplanar and very similar [pdP(S)T 2 H: –157.3(2)°; pdP(Se)T 2 H: 157.5(2)°].…”

“…To date, only anti‐periplanar conformations of the bithiophenes have been observed in the solid‐state structures of bithiophenes that are disubstituted with either chalcogenophosphines or chalcogenophosphonates derived from 2, 2′‐biphenol , , . However, this is not the case for pdP(X)T 2 P(X)pd (X = S, Se) in which only the syn‐periplanar conformations are observed.…”

Synthesis, linear and nonlinear optical properties of phosphonato-substituted bithiophenes derived from 2,2′-biphenol

“…Paper related chalcogenophosphonates. [39][40][41][42][43][44] For triarylphosphine chalcogenides, the trend in 31 P{ 1 H} NMR chemical shifts as the chalcogen is varied is S > Se > O, with the sulfides being only slightly deshielded relative to the oxides and the selenides. 21,22,42 The effect of the chalcogen on the 31 P{ 1 H} NMR chemical shifts of the phosphonato-substituted bithiophenes is quite different from that in Mo(CO) 5 PPh 2 XR 45 and Mo(CO) 5 P(OCH 2 CMe 2 CH 2 O)XR) 46 (X = O, S; R = alkyl, aryl) complexes suggesting that there is no simple inductive type correlation of 31 P{ 1 H} chemical shifts with chalcogen electronegativity and that the effect of the chalcogen on the phosphorus shielding environment is extremely sensitive to the other groups attached to the phosphorus.…”

“…[39][40][41][42][43][44] For triarylphosphine chalcogenides, the trend in 31 P{ 1 H} NMR chemical shifts as the chalcogen is varied is S > Se > O, with the sulfides being only slightly deshielded relative to the oxides and the selenides. 21,22,42 The effect of the chalcogen on the 31 P{ 1 H} NMR chemical shifts of the phosphonato-substituted bithiophenes is quite different from that in Mo(CO) 5 PPh 2 XR 45 and Mo(CO) 5 P(OCH 2 CMe 2 CH 2 O)XR) 46 (X = O, S; R = alkyl, aryl) complexes suggesting that there is no simple inductive type correlation of 31 P{ 1 H} chemical shifts with chalcogen electronegativity and that the effect of the chalcogen on the phosphorus shielding environment is extremely sensitive to the other groups attached to the phosphorus. 47 The one bond, P-Se coupling constants, | 1 J PSe |, provide insight into the electron density of the phosphorus because | 1 J PSe | has a positive correlation with the electronegativity of the phosphorus substituents, which provides a measure of the s-character of the P-Se bond, [48][49][50] and the σ-basicity of organophosphorus ligands.…”