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Type: Artigo de periódico
Title: Synthesis And X-ray Structure Of The Tetranuclear Butterfly Iridium Cluster Ir4(co)8l(μ3-η3-ph 2pc(h)cph)(μ-pph2) (l = Pcy3) And 13c{1h}, 1h, And 31p{1h} Nmr Studies Of The Compounds With L = Co, Pcy3, And P(ome)3
Author: Benvenutti M.H.A.
Vargas M.D.
Braga D.
Grepioni F.
Parisini E.
Mann B.E.
Abstract: Deprotonation of HIr4(CO)10(μ-PPh2) (1) with DBU, which gives [Ir4(CO)10(μ-PPh2)]- (2), followed by reaction with Ph2PC≡CPh and immediate protonation affords HIr4(CO)9(μ4-η3-Ph 2PC2Ph)(μ-PPh2) (3) and the novel species Ir4(CO)9(μ3-η3-Ph 2PC(H)CPh)(μ-PPh2) (4) in addition to the CO substitution products HIr4(CO)10-n(Ph2PC≡CPh) n(μ-PPh2) (n = 1 (5), 2 (6)). Compound 4 undergoes facile CO substitution reactions with phosphines and phosphites (L) to yield Ir4(CO)8L(mu;3-η3-Ph 2PC(H)CPh)(μ-PPh2) (L = PCy3 (7a), P(OMe)3 (7b), PPh3 (7c), PPhMe2 (Td)). The derivative 7a has been structurally characterized by an X-ray diffraction analysis. Crystals of 7a are triclinic, space group P1, with a = 12.626(1) Å, b = 20 405(5) Å, c = 12.493(2) Å, α = 94.16(2)°, β = 90.44(1)°, γ = 77.02(1)°, V = 3128.0 Å3, Z = 2, and 2θ range 5-50°, for 6698 measured reflections out of 6186 unique observed reflections (I0 > 2.0σ(I0)); R = 0.04, Rw = 0.04. The structure of 7a consists of a butterfly arrangement of metal atoms, whose wingtips are bridged by a PPh2 ligand, with the Ph2PC(H)CPh ligand interacting with a triangular metal face. The solution structures of compounds 4 and 7a,b have been investigated by a combination of variable-temperature 1H, 13C{1H}, and 31P{1H} NMR studies, which have established that (i) 4 is isostructural with 7a,b, with a CO in place of L, (ii) 7a,b consist of two interconverting isomers in the ratio 3.9:1 at -20°C and 1:5.9 at -60°C, respectively, and (iii) the structure determined by X-ray analysis is that of the major isomer of 7a, which is isostructural with the minor isomer of 7b. © 1993 American Chemical Society.
Rights: fechado
Identifier DOI: 
Date Issue: 1993
Appears in Collections:Unicamp - Artigos e Outros Documentos

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