Characteristics of Nickel(0), Nickel(I), and Nickel(II) in Phosphino Thioether Complexes:  Molecular Structure andS-Dealkylation of (Ph₂P(o-C₆H₄)SCH₃)₂Ni⁰

Abstract

The molecular structure of a nickel(0) complex with P,S-donor atom ligands has been characterized by X-ray crystallography. Complex 1, (Ph2P(o-C6H4)SCH3)2Ni0, prepared by Na/Hg amalgam reduction of the NiII complex [(Ph2P(o-C6H4)SCH3)2Ni](BF4)2 ([2](BF4)2), degrades photochemically with loss of CH3 radicals to yield complex 3, (Ph2P(o-C6H4)S)2NiII. Crystallographic parameters for the three compounds are as follows: 1, monoclinic space group C2/c with a = 11.467(2) Å, b = 17.613(3) Å, c = 15.733(2) Å, β = 96.450(10)°, V = 3157.5(9) Å3, and Z = 4; [2](BF4)2, monoclinic space group P2 1 / c with a = 9.417(4) Å, b = 14.822(9) Å, c = 13.773(2) Å, β = 98.55(3)°, V = 9101(14) Å3, and Z = 2; and 3, monoclinic space group P21/c with a = 9.651(2) Å, b = 12.971(8) Å, c = 12.540(2) Å, β = 110.46(2)°, V = 1470.7(11) Å3, and Z = 2. While complex 1 has a distorted tetrahedral geometry, complexes [2](BF4)2 and 3 are square planar with trans stereochemistry. The cyclic voltammogram of [2](BF4)2 in CH3CN shows two redox events assigned to NiII/I and NiI/0, whereas the thiolate 3 reveals only one reversible wave assigned to NiII/III. The chemical reduction of [2](BF4)2 with Cp2Co provided a NiI species, [(Ph2P(o-C6H4)SCH3)2NiI]+, characterized at 100 K by an axial EPR signal with g x = g y = 2.10 and g z = 1.96. Hyperfine spectral features resulting from coupling to two 31P nuclei suggests a retention of substantially square planar geometry. In contrast the isotropic character of the EPR signal of [(Ph2P(o-C6H4)SCH3)(Ph2P(o-C6H4)S)NiI], presumed to be the first product of the photochemical demethylation of 1 ultimately yielding the doubly demethylated complex 3, suggested the intervening thioether/thiolate NiI species to be pseudotetrahedral. Protonation of the nickel(0) species 1 produced a five-coordinate nickel hydride complex, [(H)(arom-PSMe)2Ni]BF4, 4.

Synthesis, Characterization, and X‐ray Crystal Structure of Macrocyclic Nickel/Iron/Sulfur Cluster Complexes

“…HSCH 2 CH 2 OCH 2 CH 2 SH and some other materials were available commercially and used as received. Fe 3 (CO) 12 , [32] Ni(dppe)Cl 2 (dppe = Ph 2 PCH 2 CH 2 PPh 2 ), [18] Ni(dppv)Cl 2 (dppv = Ph 2 PCH=CHPPh 2 ), [33] and Ni(dppb)Cl 2 (dppb = 1,2-(Ph 2 P) 2 C 6 H 4 ) [31] were prepared according to literature procedures. Preparative 12 (0.504 g, 1.0 mmol) in THF (15 mL) was treated with HSCH 2 CH 2 OCH 2 CH 2 SH (0.070 g, 0.5 mmol) and Et 3 N (0.140 mL, 1.0 mmol).…”

New binucleating ligand with two [P,S] chelation pockets on a single phenyl ring: Syntheses and X-ray structures of 1,4-bis(diphenylphosphino)-2,5-difluoro-3,6-bis(methylthio)benzene and of bimetallic complex (CO)3Fe(μ-[(PPh2)(SMe)C6F2(SMe)(PPh2)])Fe(CO)3

“…(1) did not afford expected improvements in the reaction yield. In fact, the opposite was observed: reactions were more difficult to control, and the yields were less reproducible; the reasons behind this were not investigated ð1Þ Spectroscopic characteristics of the main functional groups of 2 (d 2.17 (s) in 1 H NMR for thiomethyl and d À10.9 (m) in 31 P NMR for phosphine) are similar to those reported for other diphenylphosphine derivatives bearing o-thiomethylphenyl moieties [2,24]. Thus, it appears that the fluorines on the central phenyl ring in 2 have a negligible effect on the corresponding chemical shift values.…”

“…We have now focused our initial attention towards developing the corresponding [P,S] ligands. The organodilithium intermediate generated from 4a via double lithiumhalogen exchange readily reacts with dimethyldisulfide, yielding 1,4-bis(diphenylphosphino)-2,5-difluoro-3,6-bis-(methylthio)benzene (2) in 58% isolated yield (Eq. (1)).…”

“…Derivatives of ophosphinothiophenol ( Fig. 1, 1) are probably the most popular among such [P,S] ligands, as they effectively complex to metal centers via the formation of a five-membered chelate ring [2][3][4][5], and are relatively easy to synthesize [6]. Furthermore, the ability to vary the substituents on phosphorus and sulfur allows for facile tuning of the steric and electronic properties of such ligands.…”

“…General representation of o-phosphinothiophenols (1, R = aryl or alkyl; R 0 = aryl, alkyl, or a lone pair); structural drawings of 1,4-bis(diphenylphosphino)-2,5-difluoro-3,6-bis(methylthio)benzene(2), and its bimetallic complex 3.…”