1. Steric and electronic effects on arylthiolate coordination in the pseudotetrahedral complexes [(TpPh,Me)Ni-SAr] (TpPh,Me = hydrotris{3-phenyl-5-methyl-1-pyrazolyl}borate).
- Author
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Deb, Tapash, Anderson, Caitlin M., Chattopadhyay, Swarup, Huaibo Ma, Young Jr., Victor G., and Jensen, Michael P.
- Subjects
THIOLATES ,BORATES ,SCORPIONATES ,NICKEL compounds ,MOLECULAR shapes - Abstract
Synthesis and characterization of several new pseudotetrahedral arylthiolate complexes [(Tp
Ph,Me )Ni-SAr] (TpPh,Me = hydrotris{3-phenyl-5-methyl-1-pyrazolyl}borate; Ar = Ph, 2,4,6-i Pr3 C6 H2 , C6 H4 -4-Cl, C6 H4 -4-Me, C6 H4 -4-OMe) are reported, including X-ray crystal structures of the first two complexes. With prior results, two series of complexes are spanned, [(TpPh,Me )Ni-S-2,4,6-R'' 3 C6 H2 ] (R'' = H, Me,i Pr ) plus the xylyl analogue [(TpPh,Me )Ni-S-2,6-Me2 C6 H3 ], as well as [(TpPh,Me )Ni-S-C6 H4 -4-Y] (Y = Cl, H, Me, OMe), intended to elucidate steric and/or electronic effects on arylthiolate coordination. In contrast to [(TpMe,Me )-Ni-SAr] analogues that adopt a sawhorse conformation, the ortho-disubstituted complexes show enhanced trigonal and Ni-S-Ar bending, reflecting the size of the 3-pyrazole substituents. Moreover, weakened scorpionate ligation is implied by spectroscopic data. Little spectroscopic effect is observed in the series of para-substituted complexes, suggesting the observed effects are primarily steric in origin. The relatively electron-rich and encumbered complex [(TpPh,Me )Ni-S-2,4,6-i Pr 3C6 H2 ] behaves uniquely when dissolved in CH3 CN, forming a square planar solvent adduct with a bidentate scorpionate ligand, [(κ²-TpPh,Me )Ni(NCMe)(S-2,4,6-i Pr 3C6 H2 )]. This adduct was isolated and characterized by X-ray crystallography. Single-point DFT and TD-DFT calculations on a simplified [(κ-Tp)Ni(NCMe)(SPh)] model were used to clarify the electronic spectrum of the adduct, and to elucidate differences between Ni-SAr bonding and spectroscopy between pseudotetrahedral and square planar geometries. [ABSTRACT FROM AUTHOR]- Published
- 2014
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