Synthesis and characterisation of cobalt and nickel compounds with phosphinothiol ligands. Crystal and molecular structures of [Co{ {2- (Ph2P)-6- (Me3Si)C6H3S)} }3], [Ni{ {2- (Ph2P)-6- (Me3Si)C6H3S)} }2] and [Co{ {2- (Ph2PO)-6- (Me3Si)C6H3S} }2]

Ligand-Based Reactivity of Oxygenation and Alkylation in Cobalt Complexes Binding with (Thiolato)phosphine Derivatives

In our efforts to understand the nature of metal thiolates, we have explored the chemistry of cobalt ion supported by (thiolato)phosphine ligand derivatives. Herein, we synthesized and characterized a square-planar Co^II complex binding with a bidentate (thiolato)phosphine ligand, Co(PS1″)₂ (1) ([PS1″]^- = [P(Ph)₂(C₆H₃-3-SiMe₃-2-S)]^-). The complex activates O₂ to form a ligand-based oxygenation product, Co(OPS1″)₂ (2) ([OPS1″]^- = [PO(Ph)₂(C₆H₃-3-SiMe₃-2-S)]^-). In addition, an octahedral Co^III complex with a tridentate bis(thiolato)phosphine ligand, [NEt₄][Co(PS2*)₂] (3) ([PS2*]^2- = [P(Ph)(C₆H₃-3-Ph-2-S)₂]^2-), was obtained. Compound 3 cleaves the C-Cl bond in dichloromethane via an S-based nucleophilic attack to generate a chloromethyl thioether group. Two isomeric products, [Co(PS2*)(PSS^CH₂Cl*)] (4 and 4') ([PSS^CH₂Cl*]^- = [P(Ph)(C₆H₃-3-Ph-2-S)(C₆H₃-3-Ph-2-SCH₂Cl)]^-), were isolated and fully characterized. Both transformations, oxygenation of a Co^II-bound phosphine donor in 1 and alkylation of a Co^III-bound thiolate in 3, were monitored by spectroscopic methods. These reaction products were isolated and fully characterized. Density functional theory (DFT, the B3LYP functional) calculations were performed to understand the electronic structure of 1 as well as the pathway of its transformation to 2.

Brønsted acid-promoted C-F bond activation in [P,S]-ligated neutral and anionic perfluoronickelacyclopentanes

Treatment of L2Ni(CF2)44a-c (L = PPh3, PPh2Me, pyridine) with an external Lewis acid (trimethylsilyl triflate) gives new L-functionalized fluoronickelacyclopentanes 5a-c. Complexes L2Ni(CF2)44a,b react with the thiol form of the bidentate ligand 1,2,4-(HS)(Ph2P)Me(C6H3) [P,SH] through a unique Brønsted acid-promoted Cα-F bond activation mechanism, affording phosphine-functionalized nickelacycles bearing a phosphinothiolate ligand 6a-b. Furthermore, substituting monodentate ligands in L2Ni(CF2)44a-c with the deprotonated form of the bidentate ligand [P,S(-)] leads to the first anionic perfluoronickelacycle 7. The anionic metallacyle reacts with phosphonium salts [PHPh3](Br) and [PHPh2Me](Br) to yield HF and phosphine-functionalized nickelacycles 6a,b that still contain the terminal thiolate moiety.

Heteropolytopic phosphanylarylthiolato ligands: formation of cis isomers of nickel(II), palladium(III) and platinum(III) complexes with 1-P(Biph)-2-SHC6H4 (Biph = 1,1'-biphenyl-2,2'-diyl)

Reaction of the ditopic phosphanylarylthiol 1-P(Biph)-2-SHC(6)H(4) (BiphPSH, Biph = 1,1'-biphenyl-2,2'-diyl), prepared by lithiation-electrophilic substitution, with NiCl(2)·6H(2)O, Na(2)[PdCl(4)] and [PtI(2)(cod)] (cod = 1,5-cyclooctadiene) in a 2:1 ratio and in the presence of NEt(3) led to formation of exclusively cis isomers of the square-planar complexes cis-[M{(1-P(Biph)-2-S-C(6)H(4))-κ(2)S,P}(2)] ([M{(BiphPS)-κ(2)S,P}(2)]; M = Ni (1), Pd (2), Pt (3)). Density functional calculations support the assumption that this is probably due to intramolecular π-π interaction of the biphenyl groups, which results in enhanced stability of the cis isomers. Compound 1 is the first example of a structurally characterised mononuclear cis-bis(phosphanylthiolato)nickel(III) complex. Small amounts of the trinuclear complex [{PtI(1-P(Biph)-μ-2-S-C(6)H(4)-κ(2)S,P)}(3)] (4) are also formed besides the mononuclear platinum bis-chelate complex 3.