TY - JOUR
T1 - A study on the coordinative versatility of the zwitterionic S,N,S ligand EtNHC(S)Ph2P=NPPh2C(S)NEt in its anionic, neutral and cationic forms - determination of absolute pKa Values in CH 2Cl2 of RhI complexes
AU - Delferro, Massimiliano
AU - Cauzzi, Daniele
AU - Pattacini, Roberto
AU - Tegoni, Matteo
AU - Graiff, Claudia
AU - Tiripicchio, Antonio
PY - 2008/5
Y1 - 2008/5
N2 - The coordination properties of EtNHC(S)Ph2P=NPPh 2C(S)-NEt (HEtSNS) towards RhI species derived from [Rh(CO)2-Cl]2 and [Rh(cod)Cl]2 (cod = 1,5-cyclooctadiene) were studied. This ligand is an amphoteric zwitterion, which forms the H2EtSNS+ cation upon protonation and the EtSNS- di-anion-cation upon deprotonation. All three forms coordinate to metal centers. Their geometrical versatility allows many coordination fashions: S-monodentate; S,S-bidentate (with a bite angle spanning from 90 to 180°); S,N,S-tridentate; N,N,N-tridentate; and S,S-bridging, as determined by X-ray diffraction methods. The [Rh(CO)EtSNS] complex is a biprotic base; its conjugated acids are [Rh(CO)HEtSNS]+ and [Rh(CO)H2EtSNS] 2+, and their pKa values were determined in dichloromethane solutions. In this triad of compounds, which are geometrically similar, the RhI metal center features variable charge density as confirmed by the νCO infrared absorption frequency.
AB - The coordination properties of EtNHC(S)Ph2P=NPPh 2C(S)-NEt (HEtSNS) towards RhI species derived from [Rh(CO)2-Cl]2 and [Rh(cod)Cl]2 (cod = 1,5-cyclooctadiene) were studied. This ligand is an amphoteric zwitterion, which forms the H2EtSNS+ cation upon protonation and the EtSNS- di-anion-cation upon deprotonation. All three forms coordinate to metal centers. Their geometrical versatility allows many coordination fashions: S-monodentate; S,S-bidentate (with a bite angle spanning from 90 to 180°); S,N,S-tridentate; N,N,N-tridentate; and S,S-bridging, as determined by X-ray diffraction methods. The [Rh(CO)EtSNS] complex is a biprotic base; its conjugated acids are [Rh(CO)HEtSNS]+ and [Rh(CO)H2EtSNS] 2+, and their pKa values were determined in dichloromethane solutions. In this triad of compounds, which are geometrically similar, the RhI metal center features variable charge density as confirmed by the νCO infrared absorption frequency.
KW - Acid-base properties
KW - Coordination modes
KW - Rhodium
KW - Zwitterions
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U2 - 10.1002/ejic.200800075
DO - 10.1002/ejic.200800075
M3 - Article
SN - 0365-9496
SP - 2302
EP - 2312
JO - Berichte der deutschen chemischen Gesellschaft
JF - Berichte der deutschen chemischen Gesellschaft
IS - 14
ER -