Abstract
Previously, hydridotris(pyrazolyl)borate (Tp) Ru(II) alkyl and aryl complexes of the type TpRu(L)(NCMe)R (R = methyl or aryl; L = charge-neutral two-electron donating ligand) were demonstrated to activate aromatic C-H bonds. To determine the impact of replacing the anionic Tp ligand with charge-neutral poly(pyrazolyl)alkane ligands, [(C(pz)4)Ru(P(OCH2) 3CEt)(NCMe)Me][BAr′4] (pz = pyrazolyl, BAr′4 = tetrakis[3,5-bis(trifluoromethyl)phenyl]borate) was prepared. Heating a C6D6 solution of [(C(pz) 4)Ru(P(OCH2)3CEt)(NCMe)Me][BAr′ 4] with 1 equiv of NCMe resulted in C-H activation of the 5-position of a pyrazolyl ring to yield [(κ3-(N,C5,N)C(pz) 4)Ru(P(OCH2)3CEt)(NCMe)2] [BAr′4] and CH4. Intramolecular C-H activation of the 5-position of a pyrazolyl ring also occurred when (6-p-cymene) Ru(P(OCH2)3CEt)(Br)Ph was heated in the presence of C(pz)4 to yield [(κ3-N,C5,N)C(pz) 4]Ru(P(OCH2)3CEt)(NCMe)Br and C 6H6. Density functional theory calculations revealed that the different reactivities of TpRu(P(OCH2)3CEt)(NCMe)R and [(C(pz)4)Ru(P(OCH2)3CEt)(NCMe)Me] [BAr′4] result from the stronger binding of the Tp pyrazolyl rings to Ru(II) compared to that of C(pz)4.
Original language | English |
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Pages (from-to) | 6270-6279 |
Number of pages | 10 |
Journal | Inorganic Chemistry |
Volume | 53 |
Issue number | 12 |
DOIs | |
State | Published - Jun 16 2014 |