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The allenylidene complex [Ru(η5-C5H5)(C=C=CPh2)(CO)(PiPr3)]BF4 as a precursor of novel pyrido[1,2-a]pyrimidinyl and 1,3-thiazinyl complexes

AuthorsEsteruelas, Miguel A. ; López, Ana M. ; Oliván, Montserrat ; Oñate, Enrique
Issue Date2000
PublisherAmerican Chemical Society
CitationOrganometallics 19(21): 4327-4335 (2000)
AbstractThe allenylidene complex [Ru(η5-C5H5)(CCCPh2)(CO)(PiPr3)]BF4 (1) reacts with 2-aminopyridine to give a mixture of the complexes [Ru(η5-C5H5){2,2-diphenyl-2H-pyridinium[1,2-a]pyrimidin-4-yl}(CO)(PiPr3)]BF4 (2) and (3). The molar ratio of the isomers in the mixture depends on the reaction temperature. At temperatures lower than −30 °C, isomer 2 is the main reaction product, while at 0 °C an inverse relationship is observed. The structure of 2 has been determined by an X-ray investigation, revealing a Ru−C(bicycle) distance of 2.08(1) Å. Treatment of 2 with sodium methoxide results in the deprotonation of the NH group of the heterocycle to give the pyrido[1,2-a]pyrimidinyl derivative Ru(η5-C5H5){2,2-diphenyl-2H-pyrido[1,2-a]pyrimidin-4-yl}(CO)(PiPr3) (4), which has been also characterized by an X-ray diffraction analysis. In this case, the study reveals a Ru−C(bicycle) distance of 2.097(5) Å. The deprotonation of 2 is reversible. Thus, the addition of HBF4·OEt2 to dichloromethane solutions of 4 regenerates 2. Similarly, the treatment of 4 with methyl trifluoromethanesulfonate affords [Ru(η5-C5H5){1-methyl-2,2-diphenyl-2H-pyridinium[1,2-a]pyrimidin-4-yl}(CO)(PiPr3)]CF3SO3 (5). Complex 1 also reacts with thioisonicotinamide. The reaction yields [Ru(η5-C5H5){4,4-diphenyl-2-(p-pyridinyl)-4H-1,3-thiazinium-6−yl}(CO)(PiPr3)]BF4 (6), which in the presence of sodium methoxide affords Ru(η5-C5H5){4,4-diphenyl-2-(p-pyridinyl)-4H-1,3-thiazin-6-yl}(CO)(PiPr3) (7). The structure of 7 has been determined by an X-ray investigation, revealing a Ru−C(cycle) distance of 2.067(4) Å. The deprotonation of 6 is also reversible. Thus, the addition of HBF4·OEt2 to dichloromethane solutions of 7 regenerates 6. Similarly, treatment of 7 with methyl trifluoromethanesulfonate gives [Ru(η5-C5H5){3-methyl-4,4-diphenyl-2-(p-pyridinyl)-4H-1,3-thiazinium-6-yl}(CO)(PiPr3)]CF3SO3 (8).
Identifiersdoi: 10.1021/om000415t
issn: 0276-7333
e-issn: 1520-6041
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