(Mu-eta2:eta2-disulfido)dinickel(II) complexes supported by 6-methyl-TPA ligands.
A series of (mu-eta(2):eta(2)-disulfido)dinickel(II) complexes 2(n) have been synthesized by the reaction of Na(2)S(2) and nickel(II) complexes 1(n) supported by tris[(pyridin-2-yl)methyl]amine (TPA; 1(0)) [(6-methylpyridin-2-yl)methyl]bis[(pyridin-2-yl)methyl]amine (Me(1)TPA; 1(1)), bis[(6-methylpyridin-2-yl)methyl][(pyridin-2-yl)methyl]amine (Me(2)TPA; 1(2)) and tris[(6-methylpyridin-2-yl)methyl]amine (Me(3)TPA; 1(3)), respectively, and characterised by UV-vis and resonance Raman spectroscopy. X-ray crystallographic analyses on 2(2) and 2(3) supported by Me(2)TPA and Me(3)TPA, respectively, have revealed that the Ni(2)S(2) core is largely bent (approximately 30 degrees) along the S-S axis, being in sharp contrast to the planar Ni(2)S(2) core structure of the (mu-eta(2):eta(2)-disulfido)dinickel(II) complexes reported so far. The UV-vis spectra of 2(0) and 2(1) supported by TPA and Me(1)TPA, respectively, exhibiting an intense absorption band at approximately 360 nm together with a shoulder around 400 nm and a weak and broad absorption band around 450-600 nm, are very close to those of 2(2) and 2(3), suggesting that 2(0) and 2(1) also exhibit a similar distorted Ni(2)S(2) core structure. Resonance Raman spectra of 2(n) showed a characteristic S-S stretching vibration mode at approximately 450 cm(-1) with an isotope shift Delta nu((32)S-(34)S) = 10-15 cm(-1). The reaction of 2(n) with (p-Me-C(6)H(4))(3)P gave (p-Me-C(6)H(4))(3)P=S quantitatively based on 2(n). Hammett analysis on the sulfur atom transfer process from 2(n) to the phosphine derivatives [(p-X-C(6)H(4))P; X = OMe, Me, H and Cl] has indicated that the reaction involves an electrophilic ionic mechanism. Moreover, the order of reactivity of 2(n) toward PPh(3) has been found as 2(0) > 2(3) > 2(1) > 2(2). On the basis of these results, the ligand effects of Me(n)TPA on the structure and reactivity of the nickel(II) complexes have been discussed.
Inosako
Masayuki
M
Department of Chemistry, Graduate School of Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka, 558-8585, Japan.
Kunishita
Atsushi
A
Kubo
Minoru
M
Ogura
Takashi
T
Sugimoto
Hideki
H
Itoh
Shinobu
S
D018360:Crystallography, X-Ray; D007700:Kinetics; D008024:Ligands; D009532:Nickel / Q000737:chemistry*; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D011725:Pyridines / Q000737:chemistry*; D013057:Spectrum Analysis; D013440:Sulfides / Q000737:chemistry
D008024:Ligands; D009942:Organometallic Compounds; D011725:Pyridines; D013440:Sulfides; C431843:tris(2-pyridylmethyl)amine; D009532:Nickel; C033479:sodium sulfide