Abstract
The synthesis and reactivity of new Pt(II) complexes, including anionic d8 complexes, based on the electron-rich, hemilabile PNN-type pincer ligand C5H3N-2-(CH2PtBu 2)(CH2NEt2) are described. Formation of these complexes involves dearomatization/aromatization processes of the ligand. The chloride complex [(PNN)PtCl]+Cl- (1) was prepared and reacted with the base tBuOK to give the deprotonated, neutral chloride complex (PNN*)PtCl (2) (PNN* = C5H 3N-2-(CHPtBu2)(CH2NEt2)). Reaction of 2 with nBuLi gave the corresponding neutral hydride complex (PNN*)PtH (3), which was readily protonated by triflic acid to give the cationic hydride complex [(PNN)PtH]+OTf- (4). Unexpectedly, reaction of complex 2 with 1 equiv of RLi resulted in opening of the chelate ring, to give the corresponding anionic, dearomatized complexes Li+[(PNN*)Pt(Cl)(R)]- (R = methyl, 5; phenyl, 6). Notably, these complexes are relatively stable although they bear no stabilizing π acceptors that can lower the electron density at the metal center. Complexes 5 and 6 readily undergo protonation by HCl to form the corresponding neutral, aromatic complexes (PNN)Pt(Cl)(R) (R = methyl, 7; phenyl, 8), in which the hemilabile amine "arm" remains decoordinated and does not undergo protonation. Minor amounts of the dearomatized chloride complex 2 are also formed as a result of elimination of RH. Reaction of complexes 5 and 6 with water results in selective protonation-aromatization to give the corresponding complexes 7 and 8.
| Original language | English |
|---|---|
| Pages (from-to) | 2627-2634 |
| Number of pages | 8 |
| Journal | Organometallics |
| Volume | 27 |
| Issue number | 11 |
| DOIs | |
| Publication status | Published - Jun 9 2008 |
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ASJC Scopus subject areas
- Inorganic Chemistry
- Organic Chemistry
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Cationic, neutral, and anionic platinum(II) complexes based on an electron-rich PNN ligand. New modes of reactivity based on pincer hemilability and dearomatization. / Vuzman, Dana; Poverenov, Elena; Shimon, Linda J W; Diskin-Posner, Yael; Milstein, David.
In: Organometallics, Vol. 27, No. 11, 09.06.2008, p. 2627-2634.Research output: Contribution to journal › Article
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TY - JOUR
T1 - Cationic, neutral, and anionic platinum(II) complexes based on an electron-rich PNN ligand. New modes of reactivity based on pincer hemilability and dearomatization
AU - Vuzman, Dana
AU - Poverenov, Elena
AU - Shimon, Linda J W
AU - Diskin-Posner, Yael
AU - Milstein, David
PY - 2008/6/9
Y1 - 2008/6/9
N2 - The synthesis and reactivity of new Pt(II) complexes, including anionic d8 complexes, based on the electron-rich, hemilabile PNN-type pincer ligand C5H3N-2-(CH2PtBu 2)(CH2NEt2) are described. Formation of these complexes involves dearomatization/aromatization processes of the ligand. The chloride complex [(PNN)PtCl]+Cl- (1) was prepared and reacted with the base tBuOK to give the deprotonated, neutral chloride complex (PNN*)PtCl (2) (PNN* = C5H 3N-2-(CHPtBu2)(CH2NEt2)). Reaction of 2 with nBuLi gave the corresponding neutral hydride complex (PNN*)PtH (3), which was readily protonated by triflic acid to give the cationic hydride complex [(PNN)PtH]+OTf- (4). Unexpectedly, reaction of complex 2 with 1 equiv of RLi resulted in opening of the chelate ring, to give the corresponding anionic, dearomatized complexes Li+[(PNN*)Pt(Cl)(R)]- (R = methyl, 5; phenyl, 6). Notably, these complexes are relatively stable although they bear no stabilizing π acceptors that can lower the electron density at the metal center. Complexes 5 and 6 readily undergo protonation by HCl to form the corresponding neutral, aromatic complexes (PNN)Pt(Cl)(R) (R = methyl, 7; phenyl, 8), in which the hemilabile amine "arm" remains decoordinated and does not undergo protonation. Minor amounts of the dearomatized chloride complex 2 are also formed as a result of elimination of RH. Reaction of complexes 5 and 6 with water results in selective protonation-aromatization to give the corresponding complexes 7 and 8.
AB - The synthesis and reactivity of new Pt(II) complexes, including anionic d8 complexes, based on the electron-rich, hemilabile PNN-type pincer ligand C5H3N-2-(CH2PtBu 2)(CH2NEt2) are described. Formation of these complexes involves dearomatization/aromatization processes of the ligand. The chloride complex [(PNN)PtCl]+Cl- (1) was prepared and reacted with the base tBuOK to give the deprotonated, neutral chloride complex (PNN*)PtCl (2) (PNN* = C5H 3N-2-(CHPtBu2)(CH2NEt2)). Reaction of 2 with nBuLi gave the corresponding neutral hydride complex (PNN*)PtH (3), which was readily protonated by triflic acid to give the cationic hydride complex [(PNN)PtH]+OTf- (4). Unexpectedly, reaction of complex 2 with 1 equiv of RLi resulted in opening of the chelate ring, to give the corresponding anionic, dearomatized complexes Li+[(PNN*)Pt(Cl)(R)]- (R = methyl, 5; phenyl, 6). Notably, these complexes are relatively stable although they bear no stabilizing π acceptors that can lower the electron density at the metal center. Complexes 5 and 6 readily undergo protonation by HCl to form the corresponding neutral, aromatic complexes (PNN)Pt(Cl)(R) (R = methyl, 7; phenyl, 8), in which the hemilabile amine "arm" remains decoordinated and does not undergo protonation. Minor amounts of the dearomatized chloride complex 2 are also formed as a result of elimination of RH. Reaction of complexes 5 and 6 with water results in selective protonation-aromatization to give the corresponding complexes 7 and 8.
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U2 - 10.1021/om8001069
DO - 10.1021/om8001069
M3 - Article
VL - 27
SP - 2627
EP - 2634
JO - Organometallics
JF - Organometallics
SN - 0276-7333
IS - 11
ER -