Deprotonation of HIr4(CO)10(mu-PPh2) (1) With DBU, which gives [Ir4(CO)10(mu-PPh2)]- (2), followed by reaction with Ph2PC=CPh and immediate protonation affords HIr4(CO)9(mu4-eta3-Ph2PC2Ph)(mu-PPh2) (3) and the novel species Ir4(CO)9(mu3-eta3-Ph2PC(H)CPh)(mu-PPh2) (4), in addition to the CO substitution products HIr4(CO)10-n(Ph2PC-CPh)n(mu-PPh2) (n = 1(5),2 (6)). Compound 4 undergoes facile CO substitution reactions with phosphines and phosphites (L) to yield Ir4(CO)8L(mu3-eta3-Ph2PC(H)CPh)(mu-PPh2) (L = PCy3 (7a), P(OMe)3 (7b), PPh3 (7c), PPhMe2 (7d)). The derivative 7a has been structurally characterized by an X-ray diffraction analysis. Crystals of 7a are triclinic, space group P1BAR, with a = 12.626(1) angstrom, b = 20.405(5) angstrom, c = 12.493(2) angstrom, alpha = 94.16(2)-degrees, beta = 90.44(1)-degrees, gamma = 77.02(1)-degrees, V = 3128.0 angstrom3, Z = 2, and 2theta range 5-50-degrees, for 6698 measured reflections out of 6186 unique observed reflections (I0 > 2.0sigma(I0)); R = 0.04, R(w) = 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 H-1, C-13{H-1}, and P-31{H-1} 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-degrees-C and 1:5.9 at -60-degrees-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.
BENVENUTTI, M., VARGAS, M.D., BRAGA, D., GREPIONI, F., PARISINI, E., MANN, B.E. (1993). SYNTHESIS AND X-RAY STRUCTURE OF THE TETRANUCLEAR BUTTERFLY IRIDIUM CLUSTER IR4(CO)8L(MU-3-ETA-3-PH2PC(H)CPH)(MU-PPH2) (L=PCY3) AND C-13(H-1),H-1, AND P-31(H-1) NMR-STUDIES OF THE COMPOUNDS WITH L = CO, PCY3, AND P(OME)3. ORGANOMETALLICS, 12(8), 2955-2961 [10.1021/om00032a017].
SYNTHESIS AND X-RAY STRUCTURE OF THE TETRANUCLEAR BUTTERFLY IRIDIUM CLUSTER IR4(CO)8L(MU-3-ETA-3-PH2PC(H)CPH)(MU-PPH2) (L=PCY3) AND C-13(H-1),H-1, AND P-31(H-1) NMR-STUDIES OF THE COMPOUNDS WITH L = CO, PCY3, AND P(OME)3
BRAGA, D;GREPIONI, F;PARISINI, E;
1993
Abstract
Deprotonation of HIr4(CO)10(mu-PPh2) (1) With DBU, which gives [Ir4(CO)10(mu-PPh2)]- (2), followed by reaction with Ph2PC=CPh and immediate protonation affords HIr4(CO)9(mu4-eta3-Ph2PC2Ph)(mu-PPh2) (3) and the novel species Ir4(CO)9(mu3-eta3-Ph2PC(H)CPh)(mu-PPh2) (4), in addition to the CO substitution products HIr4(CO)10-n(Ph2PC-CPh)n(mu-PPh2) (n = 1(5),2 (6)). Compound 4 undergoes facile CO substitution reactions with phosphines and phosphites (L) to yield Ir4(CO)8L(mu3-eta3-Ph2PC(H)CPh)(mu-PPh2) (L = PCy3 (7a), P(OMe)3 (7b), PPh3 (7c), PPhMe2 (7d)). The derivative 7a has been structurally characterized by an X-ray diffraction analysis. Crystals of 7a are triclinic, space group P1BAR, with a = 12.626(1) angstrom, b = 20.405(5) angstrom, c = 12.493(2) angstrom, alpha = 94.16(2)-degrees, beta = 90.44(1)-degrees, gamma = 77.02(1)-degrees, V = 3128.0 angstrom3, Z = 2, and 2theta range 5-50-degrees, for 6698 measured reflections out of 6186 unique observed reflections (I0 > 2.0sigma(I0)); R = 0.04, R(w) = 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 H-1, C-13{H-1}, and P-31{H-1} 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-degrees-C and 1:5.9 at -60-degrees-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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.