On the Reactivity of Rhodium(I) Complexes with κP-Coordinated γ-Phosphino-Functionalized Propyl Phenyl Sulfide Ligands: Routes to Cyclic Rhodium Complexes with κC,κP- and κP,κS-Coordinated Ligands as Well as Bis(diphenylphosphino)methanide Ligands

Abstract

Reactions of dinuclear μ-chlorido rhodium(I) complexes [(RhL 2 ) 2 (μ-Cl) 2 ] (L 2 =cycloocta-1,5-diene, cod, 3; L 2 =P ∧ P: Ph 2 PCH 2 PPh 2 , dppm, 4a; Ph 2 P(CH 2 ) 2 PPh 2 , dppe, 4b; Ph 2 P(CH 2 ) 3 PPh 2 , dppp, 4c; Me 2 P(CH 2 ) 2 PMe 2 , dmpe, 4d) with γ-phosphino-functionalized propyl phenyl sulfides PhSCH 2 CH 2 -CH 2 PR 2 (R=Ph, 1; Cy, 2) afforded mononuclear rhodium(I) complexes of the type [RhCl(R 2 PCH 2 -CH 2 CH 2 SPh-κP)L 2 ] ] (R=Ph/L 2 =P ∧ P, 5a-c; R=Ph/L 2 =cod, 6; R=Cy/L 2 =P ∧ P, 7a-d; R = Cy/L 2 = cod, 8). Single-crystal X-ray diffraction analysis of 7b 3 C 6 H 6 exhibited the expected square-planar coordination of the rhodium atom having coordinated dppe-κ 2 P,P 0 , Cy 2 PCH 2 CH 2 CH 2 SPh-κP, and a chlorido ligand. Deprotonation of complexes 5b/c, 6, 7b/c, and 8 with lithium diisopropyl amide (LDA) yielded, with a selective deprotonation of the CH 2 group next to the sulfur atom (R-CH 2 group), complexes of the type [Rh{CH(SPh)CH 2 CH 2 PR 2 -κC,κP}L 2 ] (13b/c, 14, 15b/c, 16), thus being organorhodium intramolecular coordination compounds. Unexpectedly, reactions of the dppm complexes 5a and 7a with LDA led to deprotonation of the CH 2 group of the dppm ligand, resulting in formation of mononuclear rhodium complexes with a bis(diphenylphosphino)methanide-κ 2 P,P 0 ligand and a R 2 P ∧ SPh-κP,κS ligand, as well (17, 18). Single-crystal X-ray diffraction analysis of [Rh(dppm -H -κ 2 P,P 0 ) (Cy 2 PCH 2 CH 2 CH 2 SPh-κP,κS)] 3 THF (18 3 THF) shows the rhodium atom located in the center of a distorted square-planar environment having bound the P ∧ S-κP,κS ligand and the anionic dppm -H -κ 2 P, P 0 ligand with a very small P2-Rh-P3 angle (68.8(2)°) reflecting the small bite of that ligand. Addition of Tl[PF 6 ] to complexes 5-8 afforded cationic rhodium(I) complexes of the type [Rh(R 2 PCH 2 CH 2 CH 2 -SPh-κP,κS)L 2 ][PF 6 ] (9-12) bearing bidentately coordinated neutral co-ligands (P ∧ P: 9, 11; cod, 10, 12) and κP,κS-coordinated γ-phosphino-functionalized propyl phenyl sulfide ligands, as well. Single-crystal X-ray diffraction analysis of 10 reveals that the rhodium atom adopts a slightly distorted square-planar conformation. Complexes 9a-c and 11a-d were found to react with carbon monoxide, yielding cationic rhodium carbonyl complexes [Rh(CO)(R 2 PCH 2 CH 2 CH 2 SPh-κP,κS)(P ∧ P-κ 2 P,P 0 )] þ (19, 20), being in a dynamic equilibrium between two diastereomers each at room temperature, which was additionally verified by DFT calculations.

Rhodium(I) complexes with κP coordinated ω-phosphinofunctionalized alkyl phenyl sulfide, sulfoxide and sulfone ligands and their reactions with sodium bis(trimethylsilyl)amide and Ag[BF4]

“…As spacers between the two donor sites the methylene (n ¼ 1), dimethylene (n ¼ 2) and trimethylene (n ¼ 3) groups were used. As shown in Scheme 1 (routes a/b/c) the reactions afforded neutral rhodium(I) complexes (6a/b/ce11a/b/c) having bound the Ph 2 P (CH 2 ) n S(O) x Ph ligands in a kP coordination mode as it was shown for complexes 10a/11a [24] and 10c/11c [29] before. The reactions were conducted in THF at room temperature.…”

“…4. Type II ligands with a C 3 spacer (n ¼ 3) are found to form organorhodium intramolecular coordination compounds (22,23) irrespective of the nature of the sulfur functionalization (x ¼ 0e2) [24,29]. In the case of the sulfinylfunctionalized ligands (x ¼ 1) the deprotonation of the prochiral CH 2 group creates a second chiral center; noteworthy, the formation of the respective organorhodium complexes (22b, 23b) proved to be diastereoselective.…”

“…Moreover, they showed a moderate solubility in n-pentane. Complexes 22a/c and 23a/c have been prepared before by using lithium diisopropyl amide as base [24,29]. Hence, in this work the formation of these complexes has been proved by 31 P NMR spectroscopic measurements of the reaction solutions only.…”

“…Details of the preparation of starting compounds and a complete set of their NMR spectroscopic data are given in the Supplemental Material. [{Rh(cod)} 2 (m-Cl) 2 ] (4), [{Rh(dppe)} 2 (mCl) 2 ] (5), Ph 2 PCH 2 CH 2 CH 2 SPh (3a) and Ph 2 PCH 2 CH 2 CH 2 S(O) 2 Ph (3c) were prepared according to literature procedures [24,29,60,61].…”

Development and testing of a compact basis set for use in effective core potential calculations on rhodium complexes

“…[33–35], and the scalar‐relativistic Def2‐ n ZVP(PD) basis set,[36] n = S,T,Q (also known as SDD basis set), which has also been used in Refs. [37–41]. In other theoretical works, rhodium complexes were studied with a plane‐wave basis set[42–44] and with a custom‐contracted [8s6p4d] ECP basis set.…”