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]

Reactions of ω-diphenylphosphinofunctionalized alkyl phenyl sulfides Ph2P(CH2)nSPh (n = 1, 1a; 2, 2a; 3, 3a), sulfoxides Ph2P(CH2)nS(O)Ph (n = 1, 1b; 2, 2b; 3, 3b) and sulfones Ph2P(CH2)nS(O)2Ph (n = 1, 1c; 2, 2c; 3, 3c) with dinuclear chlorido bridged rhodium(I) complexes [(RhL2)2(μ-Cl)2] (L2 = cycloocta-1.5-diene, cod, 4; bis(diphenylphosphino)ethane, dppe, 5) afforded mononuclear Rh(I) complexes of the type [RhCl{Ph2P(CH2)nS(O)xPh-κP}(cod)] 1 (n/x = 1/0, 6a; 1/1, 6b; 1/2, 6c; 2/0, 8a; 2/1, 8b; 2/2, 8c; 3/0, 10a; 3/1, 10b; 3/2, 10c) and [RhCl{Ph2P(CH2)nS(O)xPh-κP}(dppe)] (n/x = 1/0, 7a; 1/1, 7b; 1/2, 7c; 2/0, 9a; 2/1, 9b; 2/2, 9c; 3/0, 11a; 3/1, 11b; 3/2, 11c) having the P^S(O)x ligands κP coordinated. Addition of Ag[BF4] to complexes 6–11 in CH2Cl2 led with precipitation of AgCl to cationic rhodium complexes of the type [Rh{Ph2P(CH2)nS(O)xPh-κP,κS/O}L2][BF4] having bound the P^S(O)x ligands bidentately in a κP,κS (13a–18a, 15b–18b) or a κP,κO (13b, 14b, 13c–18c) coordination mode. Unexpectedly, the addition of Ag[BF4] to 6a in THF afforded the trinuclear cationic rhodium(I) complex [Rh3(μ-Cl)(μ-Ph2PCH2SPh-κP:κS)4][BF4]2·4THF (12·4THF) with a four-membered Rh3Cl ring as basic framework. Addition of sodium bis(trimethylsilyl)amide to complexes 6–11 led to a selective deprotonation of the carbon atom neighbored to the S(O)x group (α-C) yielding three different types of organorhodium complexes: a) Organorhodium intramolecular coordination compounds of the type [Rh{CH{S(O)xPh}CH2CH2PPh2-κC,κP}L2] (22a–c, 23a–c), b) zwitterionic complexes [Rh{Ph2PCHS(O)xPh-κP,κS/O}L2] having κP,κS (21a, 21b) and κP,κO (20b/c, 21c) coordinated anionic [Ph2PCHS(O)xPh] ligands, and c) the dinuclear rhodium(I) complex [{Rh{μ-CH(SPh)PPh2-κC:κP}(cod)}2] (19). All complexes were fully characterized spectroscopically and complexes 15b, 15c, 12·4THF and 19·THF additionally by X-ray diffraction analysis. DFT calculations of zwitterionic complexes gave insight into the coordination mode of the [Ph2PCHS(O)Ph] ligand (κP,κS versus κP,κO).

Graphical abstractRhodium(I) complexes of type I bearing κP coordinated ω-phosphinofunctionalized alkyl phenyl sulfide (x = 0), sulfoxide (x = 1) and sulfone (x = 2) ligands Ph2P(CH2)nS(O)xPh (n = 1–3) were found to react with Ag[BF4] to yield cationic complexes of type II. Furthermore, addition of sodium bis(trimethylsiliyl)amide to complexes of type I afforded zwitterionic complexes (III) and organorhodium intramolecular coordination compounds (IV), respectively. The type of the complexes formed in these reactions can be controlled by the spacer length (n = 1–3) and the sulfur functionalization (x = 0–2). Generally, the sulfinylfunctionalized ligands (x = 1) proved to be flexidentate (κP,κS versus κP,κO) and their coordination mode in complexes of type II and III is dependent on the coligand and the spacer length.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► ω-Phosphinofunctionalized sulfides, sulfoxides and sulfones are versatile ligands. ► ω-Phosphinofunctionalized sulfoxides are flexidentate ligands. ► Anionic P^S(O)xligands form zwitterionic complexes having a “free” carbanionic center. ► Anionic P^S(O)x ligands form organometallic intramolecular coordination compounds.