Photochemical reactions of fluorinated pyridines at half-sandwich rhodium complexes: Competing pathways of reaction

TY - JOUR

T1 - Photochemical reactions of fluorinated pyridines at half-sandwich rhodium complexes

T2 - Competing pathways of reaction

AU - Procacci, B.

AU - Blagg, R.J.

AU - Perutz, R.N.

AU - Rendón, N.

AU - Whitwood, A.C.

PY - 2014/1/13

Y1 - 2014/1/13

N2 - Irradiation of CpRh(PMe)(CH) (1; Cp = η-CH) in the presence of pentafluoropyridine in hexane solution at low temperature yields an isolable η-C,C-coordinated pentafluoropyridine complex, CpRh(PMe )(η-C,C-CNF) (2). The molecular structure of 2 was determined by single-crystal X-ray diffraction, showing coordination by C3-C4, unlike previous structures of pentafluoropyridine complexes that show N-coordination. Corresponding experiments with 2,3,5,6-tetrafluoropyridine yield the C-H oxidative addition product CpRh(PMe)(CNF)H (3). In contrast, UV irradiation of 1 in hexane, in the presence of 4-substituted tetrafluoropyridines CNFX, where X = NMe, OMe, results in elimination of CH and HF to form the metallacycles CpRh(PMe)(κ-C,C-CH N(CH)CNF) (4) and CpRh(PMe )(κ-C,C-CHOCNF ) (5), respectively. The X-ray structure of 4 shows a planar RhCCNC-five-membered ring. Complexes 2-5 may also be formed by thermal reaction of CpRh(PMe)(Ph)H with the respective pyridines at 50 C.

AB - Irradiation of CpRh(PMe)(CH) (1; Cp = η-CH) in the presence of pentafluoropyridine in hexane solution at low temperature yields an isolable η-C,C-coordinated pentafluoropyridine complex, CpRh(PMe )(η-C,C-CNF) (2). The molecular structure of 2 was determined by single-crystal X-ray diffraction, showing coordination by C3-C4, unlike previous structures of pentafluoropyridine complexes that show N-coordination. Corresponding experiments with 2,3,5,6-tetrafluoropyridine yield the C-H oxidative addition product CpRh(PMe)(CNF)H (3). In contrast, UV irradiation of 1 in hexane, in the presence of 4-substituted tetrafluoropyridines CNFX, where X = NMe, OMe, results in elimination of CH and HF to form the metallacycles CpRh(PMe)(κ-C,C-CH N(CH)CNF) (4) and CpRh(PMe )(κ-C,C-CHOCNF ) (5), respectively. The X-ray structure of 4 shows a planar RhCCNC-five-membered ring. Complexes 2-5 may also be formed by thermal reaction of CpRh(PMe)(Ph)H with the respective pyridines at 50 C.

UR - http://www.scopus.com/inward/record.url?scp=84892575629&partnerID=8YFLogxK

U2 - 10.1021/om400552r

DO - 10.1021/om400552r

M3 - Article

AN - SCOPUS:84892575629

SN - 0276-7333

VL - 33

SP - 45

EP - 52

JO - Organometallics

JF - Organometallics

IS - 1

ER -