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Titolo:
CO substitution in PhCCo3(CO)(9) by 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd). Ligand fluxionality, kinetics, and X-ray structures ofPhCCo3(CO)(7)(bpcd) and Co-3(CO)(6)[mu(2)-eta(2),eta(1)-C(Ph)C=C(PPh2)C(O)CH2C(O)]-(mu(2)-PPh2)
Autore:
Bott, SG; Shen, HF; Richmond, MG;
Indirizzi:
Univ N Texas, Dept Chem, Denton, TX 76203 USA Univ N Texas Denton TX USA 76203 N Texas, Dept Chem, Denton, TX 76203 USA Univ Houston, Dept Chem, Houston, TX 77204 USA Univ Houston Houston TX USA 77204 uston, Dept Chem, Houston, TX 77204 USA
Titolo Testata:
STRUCTURAL CHEMISTRY
fascicolo: 3-4, volume: 12, anno: 2001,
pagine: 225 - 235
SICI:
1040-0400(200108)12:3-4<225:CSIPB4>2.0.ZU;2-F
Fonte:
ISI
Lingua:
ENG
Soggetto:
2,3-BIS(DIPHENYLPHOSPHINO)MALEIC ANHYDRIDE BMA; ORGANOMETALLIC COMPLEXES; DIFFRACTION STRUCTURES; MOLECULAR-STRUCTURE; CRYSTAL-STRUCTURES; ELECTRON-TRANSFER; TRICOBALT CARBON; REDOX REACTIVITY; 19-ELECTRON COMPLEXES; TETRAHEDRANE CLUSTER;
Keywords:
clusters; co substitution; P-C bond activation;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
64
Recensione:
Indirizzi per estratti:
Indirizzo: Richmond, MG Univ N Texas, Dept Chem, Denton, TX 76203 USA Univ N Texas Denton TX USA 76203 Chem, Denton, TX 76203 USA
Citazione:
S.G. Bott et al., "CO substitution in PhCCo3(CO)(9) by 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd). Ligand fluxionality, kinetics, and X-ray structures ofPhCCo3(CO)(7)(bpcd) and Co-3(CO)(6)[mu(2)-eta(2),eta(1)-C(Ph)C=C(PPh2)C(O)CH2C(O)]-(mu(2)-PPh2)", STRUCT CHEM, 12(3-4), 2001, pp. 225-235

Abstract

The reaction between the tetrahedrane cluster PhCCo3(CO)(9) (1) and the redox-active diphosphine ligand 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd) leads to the replacement of two CO groups and formation of PhCCo3(CO)(7)(bpcd) (2). Cluster 2 is thermally unstable and readily transforms into the new cluster Co-3(CO)(6)[mu (2)-eta (2) : eta (1)-C(Ph)C(PPh2)C(O)CH2(O)](mu (2)-PPh2) (3). Both clusters 2 and 3 have been isolated and fully characterized in solution by IR and NMR (P-31 and C-13) spectroscopy. VTP-31 NMR data indicate that the bpcd ligand in PhCCo3(CO)(7)(bpcd) is fluxional in solution, with two chelating and one bridging isomer being observed at 176 K in THR The kinetics for the conversion of 2 to 3 followed first-order kinetics in 1,2-dichloroethane (DCE). These data, coupled with the reaction rates being retarded in the presence of added CO, and the activationparameters (DeltaH(double dagger) = 27.1 +/- 0.3 kcal/mol and DeltaS(double dagger) = 9 +/- 1 eu) support a scheme involving a dissociative CO loss as the rate-limiting step. Clusters 2 and 3 have been structurally characterized by X-ray diffraction analyses. PhCCo3(CO)(7)(bpcd) crystallizes in themonoclinic space group P21/n: a = 10.731(2) Angstrom, b = 21.743(3) Angstrom, c = 17.143(1) Angstrom, beta = 97.522(8)degrees, V = 3965.4(8) Angstrom(3), Z = 4, d(calc) = 1.552 g (.) cm(-3); R = 0.0598, R-w = 0.0671 for 1428 observed reflections with l > 3 sigma (l). Co-3(CO)(6)[mu (2)-eta (2):eta(1)-C(Ph)C=(PPh2)C(O)CH2C(O)](mu (2)-PPh2) crystallizes in the triclinic space group P (1) over bar a = 11.572(1) Angstrom, b = 11.702(1) Angstrom, c= 15.227(1) Angstrom, alpha = 106.716(6)degrees, beta = 90.419(6)degrees, gamma = 103.676(7)degrees, V = 1912.4(3) Angstrom (3), Z = 2, d(calc) = 1.560 g (.) cm(-3); R = 0.0545, R-w = 0.0632 for 3149 observed reflections with l > 3 sigma (l). The chemistry exhibited by clusters 2 and 3 is compared with related clusters containing the diphosphine ligand 2,3-bis(diphenylphosphino)maleic anhydride (bma).

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 28/11/20 alle ore 00:55:33