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

摘要

Reactions of dinuclear μ-chlorido rhodium(I) complexes [(RhL _2)_2(μ-Cl)_2] (L_2 = cycloocta-1,5-diene, cod, 3; L_2 = PλP: Ph_2PCH _2PPh_2, dppm, 4a; Ph_2P(CH_2) _2PPh_2, dppe, 4b; Ph_2P(CH_2) _3PPh_2, dppp, 4c; Me_2P(CH_2) _2PMe_2, dmpe, 4d) with γ-phosphino-functionalized propyl phenyl sulfides PhSCH_2CH_2CH_2PR _2 (R = Ph, 1; Cy, 2) afforded mononuclear rhodium(I) complexes of the type [RhCl(R_2PCH_2CH_2CH_2SPh- ΚP)L_2] ] (R = Ph/L_2 = PλP, 5a-c; R = Ph/L_2 = cod, 6; R = Cy/L_2 = PλP, 7a-d; R = Cy/L_2 = cod, 8). Single-crystal X-ray diffraction analysis of 7b?C_6H_6 exhibited the expected square-planar coordination of the rhodium atom having coordinated dppe-Κ~2P, P′, Cy_2PCH_2CH_2CH_2SPh-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 (αCH_2 group), complexes of the type [Rh{CH(SPh)CH_2CH_2PR _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~2P, P′ ligand and a R_2PλSPh-ΚP,ΚS ligand, as well (17, 18). Single-crystal X-ray diffraction analysis of [Rh(dppm _(-H)-Κ~2P,P′)(Cy_2PCH _2CH_2CH_2SPh-ΚP,ΚS)]?THF (18?THF) shows the rhodium atom located in the center of a distorted square-planar environment having bound the PλS-ΚP,ΚS ligand and the anionic dppm_(-H)-Κ~2P,P′ 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_2PCH_2CH _2CH_2SPh-ΚP,ΚS)L_2][PF_6] (9-12) bearing bidentately coordinated neutral co-ligands (PλP: 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 _2PCH_2CH_2CH_2SPh-ΚP,ΚS) (PλP-Κ~2P,P′)]~+ (19, 20), being in a dynamic equilibrium between two diastereomers each at room temperature, which was additionally verified by DFT calculations.