Cristina Femoni

Synthesis and structural characterization of [NEt4][Fe3(μ3-O)(μ3-AuPPh3)(μ-CO)3(CO)6], the new [Au6(μ3-S)2(PPh3)6][Fe3(μ3-S)(μ-AuPPh3)(CO)9]2 and [Au6(μ3-S)2(PPh3)6][Fe5(μ3-S)2(CO)14] ionic solids containing assemblages of cluster-cations and cluster-anions

Abstract The new [Fe 3 (μ 3 -O)(μ 3 -AuPPh 3 )(μ-CO) 3 (CO) 6 ] − and [Fe 3 (μ 3 -S)(μ-AuPPh 3 )(CO) 9 ] − monoanionic congeners have been obtained by reacting the [Fe 3 (μ 3 -E)(CO) 9 ] 2− (E=O,xa0S) dianions with one equivalent of Au(PPh 3 )Cl. The gold adduct of the oxygen derivative has been crystallized as tetraethylammonium and trimethylbenzylammonium salt either from THF and n-hexane or acetone and isopropyl alcohol, and structurally characterized in its tetraethylammonium salt (monoclinic, C 2 /c (No. 15), a =15.859(2), b =12.859(2), c =40.217(8) A, β =96.41(1)° Z =8). The [Fe 3 (μ 3 -S)(μ-AuPPh 3 )(CO) 9 ] − gold adduct, in contrast, partially reverts to the parent dianion upon crystallization under the above experimental conditions, and could be precipitated only as the [Au 6 (μ 3 -S) 2 (PPh 3 ) 6 ][Fe 3 (μ 3 -S)(μ-AuPPh 3 )(CO) 9 ] 2 salt (triclinic, P 1 (No. 2), a =18.998(8), b =19.933(8), c =22.94(1) A, α =99.91(4), β =98.91(4), γ =107.42(3)°, Z =2), by addition of an equivalent of the [Au 3 (μ 3 -S)(PPh 3 ) 3 ] + sulfonium cation to the reaction mixture. The [Fe 5 (μ 3 -S) 2 (CO) 14 ] 2− dianion does not form a gold adduct even in the presence of the sulfonium cation and only the corresponding [Au 6 (μ 3 -S) 2 (PPh 3 ) 6 ][Fe 5 (μ 3 -S) 2 (CO) 14 ] salt could be obtained. The [Fe 3 (μ 3 -O)(μ 3 -AuPPh 3 )(μ-CO) 3 (CO) 6 ] − and [Fe 3 (μ 3 -S)(μ-AuPPh 3 )(CO) 9 ] − gold adducts are not isostructural and the possible factors leading to their structural diversities are discussed. The [Au 6 (μ 3 -S) 2 (PPh 3 ) 6 ][Fe 3 (μ 3 -S)(μ-AuPPh 3 )(CO) 9 ] 2 and [Au 6 (μ 3 -S) 2 (PPh 3 ) 6 ][Fe 5 (μ 3 -S) 2 (CO) 14 ] salts represent further examples of ionic solids assembled from cluster-cations and cluster-anions.

New Ni–Pt Carbonyl Clusters with a Tetrahedron of Platinum Atoms Encapsulated in an Incomplete Tetrahedron of Nickel Atoms: [Ni36Pt4(CO)45]6− and [Ni37Pt4(CO)46]6−

A fully encapsulated Pt4 tetrahedron in an incomplete tetrahedron of 36 nickel atoms is present in [Ni36 Pt4 (CO)45 ]6- (1; see picture for the metal framework), which is obtained as an inseparable mixture with [Ni37 Pt4 (CO)46 ]6- (2) by reaction of [Ni6 (CO)12 ]2- with K2 [PtCl4 ]. The trimethylbenzylammonium salts of 1 and 2 cocrystallize in a 1:1 ratio. The additional Ni atom of 2 caps the truncated vertex of 1.

Synthesis and chemical behavior of [MFe4(CO)16]n− (M=Au, Zn, Cd, Hg) clusters: X ray structure of [NMe3CH2Ph]2[Au{Fe2(CO)8}2]Cl and [PPh4]2[Cd{Fe2(CO)6(μ-CO)2}2]2CH3CN

Abstract The oxidation reaction of [Fe(CO)4]2−- with [AuBr2]−- or Au(SEt2)Cl complexes in its early stages parallels the corresponding oxidation with silver(I) derivatives by leading in sequence to [AuFe(CO)42]3− [Au4{Fe(CO)4}4]4− and the unstable [Au5Fe(CO)44]3− clusters. Further addition of gold(I) salts gives rise to formation of [AuFe2(CO)82]− and gold metal, rather than the expected gold congener of [Ag13Fe(CO)48]n−. The green [Au{Fe2(CO)8}2]− anion is also obtained by reaction of gold(III) halides with the [Fe(CO)4]2−, [Fe2(CO)8]2− or [Fe3(CO)11]2−- dianions, and it has been isolated as tetrasubstituded ammonium or phosphonium salts. The X ray structural study of its trimethylbenzylammonium salt disclosed a bow-tie metal framework centered by the unique gold atom, so that the compound may formally be considered a gold(III) complex of the [Fe2(CO)8]2− bidentate ligand. In keeping with the above description, the [Au{Fe2(CO)8}2]− anion can be reversibiy reduced to the corresponding [Au{Fe2(CO)8}2]2− and [Au{Fe2(CO)8}2]3− anions. Owing to their ready re-oxidation by moisture or air to the parent compound, both anions could not be isolated. The probable change of gold coordination in these formally Au(II) and Au(I) di- and tri-anions is suggested by their red color, whereas the change in the carbonyl stereochemistry is pointed out by the presence of edge bridging carbonyl ligands in their IR spectra. In the attempt to simulate the above structural changes, we tried the synthesis of related d9 Cu(II) and d10 Cu(I), Ag(I), Zn(II), Cd(II) and Hg(II) congener complexes of the [Fe2(CO)8]2−- ligand. The new red-orange [M{Fe2(CO)8}2]2− (M=Zn, Cd, Hg) dianions have been obtained in almost quantitative yields by reacting [Fe2(CO)8]2− with 0.5 equivalents of MCl2 and display infrared spectra identical to that of [Au{Fe2(CO)8}2]2− The structure of the [Cd{Fe2(CO)8}2]2− dianion in its PPh4+ salt confirmed both the presence of isomerized [Fe2(CO)6(μ-CO)2]2− ligands and their twist toward a tetrahedral coordination around the central cadmium atom.

Dirhodium(II) carboxylate complexes as building blocks. Synthesis and structures of square boxes with tilted walls

The crystal structures of four new molecular boxes with substituted benzene-1,4-dicarboxylate side walls are described, showing how substituents larger than hydroxyl cause the walls to tilt in the solid state.

Dirhodium(II) carboxylate complexes as building blocks. Synthesis of dimeric species as connectors for macrocycles

Abstract Two complexes of the form (AcO)2Rh2LRh2(OAc)2 in which two Rh24+ units are covalently linked have been prepared by reaction of Rh2(OAc)4 with bischelating tetracarboxylate ligand L =( − O 2 CC ( Me ) 2 O )) 2 PhPh ( OC ( CH 3 ) 2 CO 2 − ) 2 in N,N-dimethylaniline. A crystal structure of the major (kinetic) product showed, unexpectedly, that it contained two 14 membered chelate rings, with the isomeric minor (thermodynamic) product having two 12 membered chelate rings.

Dirhodium(II) carboxylates as building blocks. Macrocyclic dimers with vertically stacked Rh24+ units

Reaction of Rh2(OAc)4 and H2L (=2,7-di-tert-butyl-9,9-dimethyl-4,5-xanthenedicarboxylic acid) in N,N-dimethylaniline gave the singly bridged dimer (AcO)3Rh2LRh2(OAc)3 and three doubly bridged dimers, (AcO)2Rh2L2Rh2(OAc)2, (HL)(AcO)Rh2L2Rh2(OAc)2, and (HL)(AcO)Rh2L2Rh2(OAc)(HL). Crystal structures of the last two compounds showed a macrocyclic core with a trans arrangement of bridging dicarboxylates, with one or two of the four remaining acetate ligands replaced by a bridging ligand bound through one carboxylate only. The rhodium cages are separated by 4.5 A in the direction of the Rh–Rh axes, and offset horizontally by 2.5 A so that a rhodium atom of one cage lies over a carboxylate oxygen of the other, with Rh⋯O distances of 2.248–2.286 A.

New high-nuclearity Ni–Pt carbonyl clusters: synthesis and X-ray structure of the ordered [Ni24Pt14(CO)44]4− and the substitutionally Ni/Pt disordered [Ni10(Ni6−xPtx)Pt8(CO)30]4− (x = 1.92) tetraanions

The reaction of [NnBu4]2[Ni6(CO)12] in THF solution with 1.5-2 equivalents of K2PtCl4 leads to formation of the [Ni24Pt14(CO)44]4- and [Ni10(Ni6-xPtx)Pt8(CO)30]4- (x approximately 2) tetraanions, the latter presents a localised substitutional Ni/Pt disorder and an unprecedented close-packed metal structure.

Dirhodium(II) carboxylates as building blocks. Synthesis and structures of cis-chelate complexes

Dirhodium tetracarboxylate complexes (C)Rh2(OAc)2 and (C)2Rh2, where C is a chelating dicarboxylate of general form meta-C6H4(OC(CH3)2CO2−)2, were prepared by heating Rh2(OAc)4 and diacids in N,N-dimethylaniline. The structures of six new complexes with one or two chelate rings were obtained, with pyridine ligands (or in one case N,N-dimethylaniline) co-ordinated to rhodium. The geometries of the molecules are similar, with the aromatic part of the chelate ring tilted out of the plane of the Rh–O cage by 57.5 to 66.6°. The monochelate Rh2{C6H4(OC(CH3)2CO2)2-m}(OAc)2·2ButPy (ButPyxa0=xa04-tert-butylpyridine) packed in the crystal to generate a hexagonal network of channels of (minimum) diameter 5 A due to vertical stacking of its axial pyridine ligands. Several other instances of intramolecular CH–π and intermolecular π–π interactions were noted in the packing diagrams. The bischelate Rh2{Ar(OC(CH3)2CO2)2-m}2·PhNMe2, with Arxa0=xa04,6-di-tert-butylphenyl, has a polymeric structure displaying a new mode of arene co-ordination. The aromatic ring of the N-bound aniline co-ordinates to a neighbouring dirhodium complex via the para carbon atom with a Rh–C distance of 2.709 A.