The [Co9P(CO)21]2- anion has been isolated from the products of the reaction between Na[Co(CO)4] and PCl5 in tetrahydrofuran at reflux. The structure of the cluster anion [Co9P(CO)21]2- in its tetraphenylphosphonium salt has been elucidated by X-ray analysis. The crystals are monoclinic, space group P21n, a = 12.528(3), b = 14.711(5), c = 19.312(6) Å, β = 93.68(2)°, Z = 2. Final R = 0.065 for 2300 unique reflections having I > 3σ(I). The anion, which is disordered about an inversion center, consists of a monocapped square antiprismatic cluster containing an interstitial phosphide and surrounded by 13 terminal and 8 edge-bridging carbonyl ligands. Average values are: Co-Co 2.685] Å, and Co-P 2.256] Å. The [Co10P(CO)22]3- anion has been obtained by condensation of the [Co9P(CO)21]2- anion with [Co(CO)4]- in tetrahydrofuran at reflux. While the [Co9P(CO)21]2- anion is stable under CO, the [Co10P(CO)22]3- anion is decomposed to [Co9P(CO)21]2- and [Co(CO)4]-. The benzyltri-methylammonium salt of the [Co10P(CO)22]3- anion has been studied by X-ray analysis. It gives triclinic crystals, space group P, a = 11.452(3), b = 23.510(6), c = 25.606(4) Å, α = 112.46(1) β, p = 95.79(1), γ = 73.548(2)°, Z = 4. Final R = 0.041 for 8600 unique reflections having I > 3σ(). There are two independent trianions in the asymmetric unit, both showing similar geometries, consisting of bicapped square antiprismatic clusters with a central P atom, each bearing 10 terminal and 12 edge-bridging carbonyl ligands, 8 of which, bound to the capping metals, are markedly asymmetric. Average values are: Co-Co 2.678 Å, and Co-P 2.262 Å. Electrochemistry shows that [Co9P(CO)21]2- and [Co10P(CO)22]3- in acetonitrile solution undergo either a one-electron oxidation or a two-electron reduction. This latter process appears as a single step in the case of the dianion and as two separated one-electron steps in the case of the trianion. All the processes are accompanied by slow chemical complications, thus testifying that no stable redox congeners exist for these phosphide clusters.

Synthesis and X-ray characterization of the phosphido - Carbonyl cluster anions [CO 9(μ 8-P)(CO) 21] 2- and [CO 10(μ 8-P)(CO) 22] 3 / G. Ciani, A. Sironi, S. Martinengo, L. Garlaschelli, R. Della Pergola, P. Zanello, F. Laschi, N. Masciocchi. - In: INORGANIC CHEMISTRY. - ISSN 0020-1669. - 40:16(2001), pp. 3905-3911.

Synthesis and X-ray characterization of the phosphido - Carbonyl cluster anions [CO 9(μ 8-P)(CO) 21] 2- and [CO 10(μ 8-P)(CO) 22] 3

G. Ciani
Primo
;
A. Sironi
Secondo
;
L. Garlaschelli;
2001

Abstract

The [Co9P(CO)21]2- anion has been isolated from the products of the reaction between Na[Co(CO)4] and PCl5 in tetrahydrofuran at reflux. The structure of the cluster anion [Co9P(CO)21]2- in its tetraphenylphosphonium salt has been elucidated by X-ray analysis. The crystals are monoclinic, space group P21n, a = 12.528(3), b = 14.711(5), c = 19.312(6) Å, β = 93.68(2)°, Z = 2. Final R = 0.065 for 2300 unique reflections having I > 3σ(I). The anion, which is disordered about an inversion center, consists of a monocapped square antiprismatic cluster containing an interstitial phosphide and surrounded by 13 terminal and 8 edge-bridging carbonyl ligands. Average values are: Co-Co 2.685] Å, and Co-P 2.256] Å. The [Co10P(CO)22]3- anion has been obtained by condensation of the [Co9P(CO)21]2- anion with [Co(CO)4]- in tetrahydrofuran at reflux. While the [Co9P(CO)21]2- anion is stable under CO, the [Co10P(CO)22]3- anion is decomposed to [Co9P(CO)21]2- and [Co(CO)4]-. The benzyltri-methylammonium salt of the [Co10P(CO)22]3- anion has been studied by X-ray analysis. It gives triclinic crystals, space group P, a = 11.452(3), b = 23.510(6), c = 25.606(4) Å, α = 112.46(1) β, p = 95.79(1), γ = 73.548(2)°, Z = 4. Final R = 0.041 for 8600 unique reflections having I > 3σ(). There are two independent trianions in the asymmetric unit, both showing similar geometries, consisting of bicapped square antiprismatic clusters with a central P atom, each bearing 10 terminal and 12 edge-bridging carbonyl ligands, 8 of which, bound to the capping metals, are markedly asymmetric. Average values are: Co-Co 2.678 Å, and Co-P 2.262 Å. Electrochemistry shows that [Co9P(CO)21]2- and [Co10P(CO)22]3- in acetonitrile solution undergo either a one-electron oxidation or a two-electron reduction. This latter process appears as a single step in the case of the dianion and as two separated one-electron steps in the case of the trianion. All the processes are accompanied by slow chemical complications, thus testifying that no stable redox congeners exist for these phosphide clusters.
Settore CHIM/03 - Chimica Generale e Inorganica
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2434/188294
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