Iridium(i) complexes bearing hemilabile coumarin-functionalised N-heterocyclic carbene ligands with application as alkyne hydrositytation catalysts
Küçük Resim Yok
Tarih
2021
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Royal Soc Chemistry
Erişim Hakkı
info:eu-repo/semantics/openAccess
Özet
A set of iridium(I) complexes of formula IrCl(kappa C,eta(2)-I(R)Cou(R))(cod) or IrCl(kappa C, eta(2)-Bz(lR)Cou(R))(cod) (cod = 1,5-cyclooctadiene; Cou = coumarin; I = imidazolin-2-carbene; Bzl = benzimidazolin-2-carbene) have beeen prepared from the corresponding azolium salt and [ir(mu-OMe)(cod)](2) in THE at room temperature. The crystalline structures of 4b and 5b show a distorted trigonal bipyramidal configuration in the solid state with a coordinated coumarin moiety. In contrast, an equilibrium between this pentacoordinated structure and the related square planar isomer is observed in solution as a consequence of the hemilability of the pyrone ring. Characterization of both species by NMR was achieved at the low and high temperature limits, respectively. In addition, the thermodynamic parameters of the equilibrium, Delta H-R and Delta S-R were obtained by VT H-1 NMR spectroscopy and fall in the range 22-33 kJ mol(-1) and 72-113 J mol(-1) k(-1), respectively. Carbonylation of IrCl(kappa C,eta(2)-BzI(Tol)Cou(7.8-Me2))(cod) resulted in the formation of a bis-CO derivative showing no hemilabile behaviour. The newly synthesised complexes efficiently catalyze the hydrosilylation of alkynes at room temperature with a preference for the beta-(Z) vinylsilane isomer.
Açıklama
Anahtar Kelimeler
C-H Activation, Rhodium(I) Complexes, Terminal Alkynes, Platinum Catalysts, Metal-Complexes, Hydrosilylation, Hydrogenation, Coordination, Reactivity, Efficient
Kaynak
Dalton Transactions
WoS Q Değeri
Q1
Scopus Q Değeri
Q1
Cilt
50
Sayı
32
