Carbonylnickelates. 3. Synthesis and chemical characterization of the [Ni12(CO)21H4-n]n- (n=2, 3, 4) clusters.

The hydrolysis of the [Ni6(CO)12]2- dianion under buffered conditions results in the synthesis of the interstitial hydride derivatives [Ni12(CO)21H2]2- and [Ni12(CO)21H]3-. The two compounds are related by an easily reversible protonation-deprotonation equilibrium. In contrast, deprotonation of [Ni12(CO)21H]3- to the corresponding [Ni12(CO)21]4- tetraanion is possible only under severe conditions. The tetraanion has been obtained as a byproduct of the synthesis of [Ni6(CO)12]2- by reduction of Ni(CO)4 in KOH-saturated methanolic solution. The [Ni12(CO)21H4-n]n- (n = 2, 3, 4) derivatives have been isolated in pure crystalline form with a variety of tetrasubstituted ammonium or phosphonium cations. All these dodecanuclear nickel carbonyl clusters are rapidly degraded by carbon monoxide (25\ub0C, 1 atm) and possess limited thermal stability. Degradation of [Ni12(CO)21H2]2- by carbon monoxide in THF solution affords the binuclear hydride derivative [Ni2(CO)6H]- and Ni(CO)4. Degradation of [Ni12(CO)21H]3-, in addition to the former products, gives rise to [Ni5(CO)12]2-, which becomes the only product, together with Ni(CO)4, when starting from [Ni12(CO)21]4-

Hexagonal close packing of metal atoms in the new polynuclear anions [Rh13(CO)24H5-n]n- (n=2 or 3); x-ray structure of [(Ph3P)2N]2[Rh13(CO)24H3].

The [Rh13(CO)24H5-n]n- (n = 2 or 3) anions have been isolated from the reaction of the [Rh12(CO) 30]2- dianion with hydrogen; they are structurally related to a close hexagonal packing of rhodium atoms having mean distances of 2.81 \uc5

Synthesis and characterization of [Rh7(CO)16X]2- anions (X=Br,I)

The reaction of Rh6(CO)16 with an excess of tetraalkylammonium halides in tetrahydrofuran gives the heptanuclear [Rh7(CO)16X]2- anions (X = Br, I), which have been isolated and characterised. The same anions were obtained by condensation of the Rh2(CO)4X2 carbonyl halides with the hexanuclear [Rh6(CO)15]2- anion, or by reaction of the [Rh7(CO)16]3- anion with iodine

Synthesis of bimetallic Fe-Ni carbonyl clusters: crystal structure of [N(CH3)3CH2Ph][Fe3Ni(CO)8(\uf06d-CO)4(\uf06d-3-H)].

Redox condensation of [Fe3(CO)11]2- with Ni(CO)4 in tetrahydrofuran affords the tetranuclear dianion [Fe3Ni(CO)12]2-. Subsequent protonation with acids results in formation of the corresponding [Fe3Ni(CO)12H]- anion. This monoanionic species has also been obtained by reaction of [Fe3(CO)11]2- with NiCl2\ub7xEtOH. Both Fe3Ni systems have been isolated in the solid state in high yield with a variety of tetrasubstituted ammonium and phosphonium salts. An X-ray diffraction study of the trimethylbenzylammonium salt of [Fe3Ni(CO)12H]- reveals a structure with a tetrahedron of metal atoms surrounded by eight terminal and four edge-bridging carbonyl groups. The hydride ligand has been located over the center of an Fe2Ni face at a distance of 0.60 (3) \uc5 from the trimetal plane. The corresponding [Fe3Ni(CO)12]2- dianion is suggested to posses an analogous structure on the basis of its IR spectrum. Crystallographic data for [C10H16N]+[C12HFe 3NiO12]-: fw 713.64, triclinic, space group P1, Z = 2, a = 7.416 (1) \uc5, b = 13.849 (2) \uc5, c = 14.108 (2) \uc5, \u3b1 = 103.13 (2)\ub0, \u3b2 = 103.15 (2)\ub0, \u3b3 = 99.23 (2)\ub0, R(F2) = 0.030 for 3860 reflections measured at room temperature