These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Synthesis of trimethylplatinum(IV) complexes with N,N- and N,O-heterocyclic carbene ligands and their reductive C-C elimination reactions.
    Author: Lindner R, Wagner C, Steinborn D.
    Journal: J Am Chem Soc; 2009 Jul 01; 131(25):8861-74. PubMed ID: 19505098.
    Abstract:
    Reactions of the platinum(IV) complexes [PtMe(3)(OCMe(2))(3)](BF(4)) (1(BF(4))), [(PtMe(3)I)(4)] (2), and [PtMe(3)I(py)(2)] (3) with the N,N-heterocyclic carbene 1,3-dimethylimidazol-2-ylidene (N,N-hc, 4) resulted in a rapid reductive elimination of ethane, yielding platinum(II) complexes [PtMe(N,N-hc)(3)](+) (7), trans-[PtMeI(N,N-hc)(2)] (8), and cis-[PtMe(py)(N,N-hc)(2)](+) (10), respectively. Subsequent substitution of the iodo ligand in 8 by pyridine resulted in the formation of trans-[PtMe(py)(N,N-hc)(2)](CF(3)COO) (9(CF(3)COO)). 9 and 10 are stereoisomers. In contrast to this, the analogous reaction of [PtMe(3)(OCMe(2))(3)](BF(4)) (1(BF(4))) with the N,O-heterocyclic carbene 3-methyloxazol-2-ylidene (N,O-hc, 5) was found to yield the tris(carbene)trimethylplatinum(IV) compound [PtMe(3)(N,O-hc)(3)](BF(4)) (12(BF(4))), which is thermally stable up to 218 degrees C in the solid state. Furthermore, reactions of [{PtMe(3)(acac)}(2)] (15) with the N,X-heterocyclic carbenes (X = N, O, S; N,S-hc = 3-methylthiazol-2-ylidene, 6) resulted in the formation of monocarbenetrimethylplatinum(IV) complexes [PtMe(3)(acac)(N,X-hc)] (X = N, 16; X = O, 17; X = S, 18), which were found to be stable against reductive C-C elimination at ambient temperature. Reactions of 16 and 17 with 2,2'-bipyridine (bpy) in the presence of stoichiometric amounts of H(BF(4)) yielded cationic monocarbeneplatinum(IV) complexes, which were isolated as tetrafluoroborate salts [PtMe(3)(bpy)(N,X-hc)](BF(4)) (X = N, 19(BF(4)); X = O, 20(BF(4))). The compounds have been fully characterized analytically and NMR spectroscopically, and for the bis(carbene)platinum(II) compound 9(CF(3)COO) as well as the monocarbeneplatinum(IV) compounds 16 and 20(BF(4)) by single-crystal X-ray diffraction analyses. DFT calculations of mono-, bis-, and tris(carbene)trimethylplatinum(IV) complexes and their propensity to reductive eliminate ethane were performed. In accordance with the experimental findings, a much higher stability of the tris(N,O-hc)- compared with the tris(N,N-hc)trimethylplatinum(IV) complexes against reductive ethane elimination was found, which could be ascribed mainly to a higher steric demand of the N,N-hc ligand.
    [Abstract] [Full Text] [Related] [New Search]