Peraurated nickel carbide carbonyl clusters: the cationic [Ni6(C)(CO)8(AuPPh3)8]2+ monocarbide and the [Ni12(C)(C2)(CO)17(AuPPh3)3]- anion containing one carbide and one acetylide unit.

Two new peraurated Ni-carbide carbonyl clusters have been prepared and structurally characterized, i.e. [Ni6(C)(CO)8(AuPPh3)8](2+) and [Ni12(C)(C2)(CO)17(AuPPh3)3](-). The latter is the first molecular cluster containing one carbide atom and one tightly bonded C2-unit. These display sub-van der Waals contacts suggesting the incipient formation of more extended C-C bonding.

Octahedral co-carbide carbonyl clusters decorated by [AuPPh3]⁺ fragments: synthesis, structural isomerism, and aurophilic interactions of Co6C(CO)12(AuPPh3)4.

The Co6C(CO)12(AuPPh3)4 carbide carbonyl cluster was obtained from the reaction of [Co6C(CO)15](2-) with Au(PPh3)Cl. This new species was investigated by variable-temperature (31)P NMR spectroscopy, X-ray crystallography, and density functional theory methods. Three different solvates were characterized in the solid state, namely, Co6C(CO)12(AuPPh3)4 (I), Co6C(CO)12(AuPPh3)4·THF (II), and Co6C(CO)12(AuPPh3)4·4THF (III), where THF = tetrahydrofuran. These are not merely different solvates of the same neutral cluster, but they contain three different isomers of Co6C(CO)12(AuPPh3)4. The three isomers I-III possess the same octahedral [Co6C(CO)12](4-) carbido-carbonyl core differently decorated by four [AuPPh3](+) fragments and showing a different Au(I)···Au(I) connectivity. Theoretical investigations suggest that the formation in the solid state of the three isomers during crystallization is governed by packing and van der Waals forces, as well as aurophilic and weak π-π and π-H interactions. In addition, the closely related cluster Co6C(CO)12(PPh3)(AuPPh3)2 was obtained from the reaction of [Co8C(CO)18](2-) with Au(PPh3)Cl, and two of its solvates were crystallographically characterized, namely, Co6C(CO)12(PPh3)(AuPPh3)2·toluene (IV) and Co6C(CO)12(PPh3)(AuPPh3)2·0.5toluene (V). A significant, even if minor, effect of the cocrystallized solvent molecules on the structure of the cluster was observed also in this case.

Homoleptic and heteroleptic Au(I) complexes containing the new [Co5C(CO)12](-) cluster as ligand.

The new [{Co5C(CO)12}Au{Co(CO)4}](-), , cluster has been obtained from the reaction of [Co6C(CO)15](2-) with two equivalents of [AuCl4](-). reacts with an excess of HBF4 resulting in the formation of [{Co5C(CO)12}2Au](-), . The new derivatives [Co5C(CO)12(AuPPh3)], , and [Co5C(CO)11(AuPPh3)3], , have been obtained by reacting with two and four equivalents of [Au(PPh3)Cl], respectively. All the new species have been structurally characterised by means of X-ray crystallography as their [NEt4][], [NEt4][], [NMe3(CH2Ph)][], and thf·0.5C6H14 salts and solvates. may be viewed as a homoleptic Au(i) complex containing two [Co5C(CO)12](-) clusters as ligands. Similarly, and are heteroleptic Au(i) complexes containing one [Co5C(CO)12](-) cluster ligand as well as [Co(CO)4](-) or PPh3. Conversely, contains the [Co5C(CO)11](3-) cluster stabilized by three [AuPPh3](+) fragments. and have been investigated in solution by means of electrochemical and spectroelectrochemical methods, revealing a very rich redox propensity to form the closely related (n = 1-3) and (n = 0-3) species.

Hydride migration from a triangular face to a tetrahedral cavity in tetranuclear iron carbonyl clusters upon coordination of [AuPPh(3)](+) fragments.

Metal hydrides are of fundamental importance in chemistry, both as solid-state materials and molecular compounds. The first low-valent molecular metal cluster containing an interstitial four-coordinate hydride in a tetrahedral site is decribed, which undergoes hydride migration from the surface to the tetrahedral cavity of the cluster upon coordination of a [AuPPh3 ](+) fragment. The [HFe4 (CO)12 (AuPPh3 )2 ](-) mono-anion, which contains a surface µ3 -H, was obtained from the reaction of [HFe4 (CO)12 ](3-) with two equivalents of [Au(PPh3 )Cl]. This is, in turn, transformed into the neutral [HFe4 (CO)12 (AuPPh3 )3 ] upon addition of a third [AuPPh3 ](+) fragment, with concomitant migration of the unique hydride from the surface of the cluster to its tetrahedral cavity. All of these species have been fully characterized in solution by means of IR and multinuclear NMR spectroscopy, and in the solid state by single-crystal X-ray diffractometry.

The redox chemistry of [Co6C(CO)15](2-): a synthetic route to new co-carbide carbonyl clusters.

The oxidation and reduction reactions of [Co6C(CO)15](2-) have been studied in detail, leading to the isolation of several new Co-carbide carbonyl clusters. Thus, [Co6C(CO)15](2-) reacts in tetrahydrofuran (THF) with oxidants such as HBF4·Et2O and [Cp2Fe][PF6], resulting first in the formation of the previously reported [Co6C(CO)14](-); then, in CH2Cl2, the new dicarbide [Co11C2(CO)23](2-) is formed. The latter may be further oxidized, yielding the isostructural monoanion [Co11C2(CO)23](-), whereas its reduction with (cyclopentadienyl)2Co affords the unstable trianion [Co11C2(CO)23](3-), which decomposes during workup. Oxidation of [Co6C(CO)15](2-) in CH3CN with [C7H7][BF4] affords the same major products, and besides, the new monoacetylide [Co10(C2)(CO)21](2-) was obtained as side-product. Conversely, the reduction of [Co6C(CO)15](2-) in THF with increasing amounts of Na/naphthalene results in the following species: [Co6C(CO)13](2-), [Co11(C2)(CO)22](3-), [Co7C(CO)15](3-), [Co8C(CO)17](4-), [Co6C(CO)12](3-), and [Co(CO)4](-). The new [Co11C2(CO)23](-), [Co11C2(CO)23](2-), [Co10(C2)(CO)21](2-), [Co8C(CO)17](4-), [Co6C(CO)12](3-), and [Co7C(CO)15](3-) clusters were structurally characterized. Moreover, the paramagnetic species [Co11C2(CO)23](2-) and [Co6C(CO)12](3-) were investigated by means of electron paramagnetic resonance spectroscopy. Finally, electrochemical studies were performed on [Co11C2(CO)23](n-) (n = 1-3).

Structural rearrangements induced by acid-base reactions in metal carbonyl clusters: the case of [H(3-n)Co15Pd9C3(CO)38]n- (n = 0-3).

The new bimetallic [HCo15Pd9C3(CO)38](2-) tri-carbide carbonyl cluster has been obtained from the reaction of [H2Co20Pd16C4(CO)48](4-) with an excess of acid in CH2Cl2 solution. The mono-hydride di-anion can be reversibly protonated and deprotonated by means of acid-base reactions leading to closely related [H(3-n)Co15Pd9C3(CO)38](n-) (n = 0-3) clusters. The crystal structures of the three anionic and the neutral clusters have been determined as their H3Co15Pd9C3(CO)38·2thf, [NEt4][H2Co15Pd9C3(CO)38]·0.5C6H14, [NMe3(CH2Ph)]2[HCo15Pd9C3(CO)38]·C6H14 and [NEt4]3[Co15Pd9C3(CO)38]·thf salts. They are composed of a Pd9(µ3-CO)2 core stabilised by three Co5C(CO)12 organometallic fragments. The poly-hydride nature of these clusters has been indirectly inferred via chemical, electrochemical and magnetic measurements. Besides, cyclic voltammetry shows that the [H(3-n)Co15Pd9C3(CO)38](n-) (n = 1-3) anions are multivalent, since they undergo two or three reversible oxidations. SQUID measurements of [HCo15Pd9C3(CO)38](2-) indicate that this even electron cluster is paramagnetic with two unpaired electrons, giving further support to its hydride nature. Finally, structural studies show that the Pd9 core of [H(3-n)Co15Pd9C3(CO)38](n-) (n = 0,1) is a tri-capped octahedron, which becomes a tri-capped trigonal prism in the more charged [H(3-n)Co15Pd9C3(CO)38](n-) (n = 2,3) anions. Such a significant structural rearrangement of the metal core of a large carbonyl cluster upon protonation-deprotonation reactions is unprecedented in cluster chemistry, and suggests that interstitial hydrides may have relevant stereochemical effects even in large carbonyl clusters.

Intramolecular d10-d10 interactions in a Ni6C(CO)9(AuPPh3)4 bimetallic nickel-gold carbide carbonyl cluster.

The Ni6C(CO)9(AuPPh3)4 bimetallic carbide carbonyl cluster was obtained from the reaction of [Ni9C(CO)17](2-) with Au(PPh3)Cl. It contains a rare carbon-centered (distorted) Ni6C octahedral core decorated by four Au(PPh3) fragments. These are µ3-bonded to four contiguous Ni3-triangular faces and display weak intramolecular Au···Au d(10)-d(10) interactions. The cluster has been characterized in the solid state on two different solvato crystals, i.e., Ni6C(CO)9(AuPPh3)4·THF and Ni6C(CO)9(AuPPh3)4·THF·0.5C6H14. The two solvates show some interesting differences concerning the weak Au···Au contacts. Density functional theory calculations have demonstrated that the presence of the two isomers is related to solid-state packing effects and not to the existence of two double minima in the potential energy surface. This, in turn, confirms that Au···Au d(10)-d(10) interactions are rather soft and thus influenced also by weak van der Waals forces because of the interaction of the cluster with the cocrystallized solvent molecules.

Selective synthesis of the [Ni36Co8C8(CO)48]6- octa-carbide carbonyl cluster by thermal decomposition of the [H2Ni22Co6C6(CO)36]4- hexa-carbide.

The thermal decomposition in thf solution of [H2Ni22Co6C6(CO)36](4-) results in the new [HNi36Co8C8(CO)48](5-) bimetallic Ni-Co octa-carbide, which can be converted into the closely related [H6-nNi36Co8C8(CO)48](n-) (n = 3-6) polyhydrides by means of acid-base reactions. The structure of the [Ni36Co8C8(CO)48](6-) hexa-anion has been established via X-ray crystallography, showing that the eight interstitial carbide atoms are lodged within different metal cages. Thus, two C-atoms are enclosed within regular square anti-prismatic Ni8C cages, four within irregular Ni8C square anti-prismatic cages, and the last two within mono-capped trigonal prismatic Ni5Co2C cages. The structure of [Ni36Co8C8(CO)48](6-) is non-compact and closely related to [Ni32C6(CO)38](6-) and [HNi38C6(CO)44](5-). [Ni36Co8C8(CO)48](6-) approaches the nanosize regime and the whole molecular ion has a diameter (measured from the outer oxygen atoms) of ca. 1.61 nm.

PPh3-derivatives of [Pt3n(CO)6n]2- (n = 2-6) Chini's clusters: syntheses, structures, and 31P NMR studies.

The reaction of the [Pt3n(CO)6n](2-) (n = 2-6) Chini's clusters with increasing amounts of PPh3 has been investigated in detail by combined FT-IR, (31)P{(1)H} NMR, and electrospray ionization-mass spectrometry (ESI-MS) studies, showing that up to three CO ligands are gradually substituted by PPh3, resulting in isonuclear phosphine-substituted anionic clusters of general formula [Pt3n(CO)(6n-x)(PPh3)(x)](2-) (n = 2-6; x = 1-3). Further addition of PPh3 results in the elimination of the neutral Pt3(CO)3(PPh3)3 species and formation of lower nuclearity anionic clusters. [Pt12(CO)22(PPh3)2](2-) and [Pt9(CO)16(PPh3)2](2-) have been structurally characterized, and they maintain the trigonal prismatic structures of the parent homoleptic clusters, with the two PPh3 ligands bonded to different external Pt3-triangles in relative cis-position. Conversely, the crystal structure of [Pt6(CO)10(PPh3)2](2-) shows that its metal cage is transformed from trigonal prismatic to trigonal antiprismatic after CO/PPh3 exchange.

Ni-Cu tetracarbide carbonyls with vacant Ni(CO) fragments as borderline compounds between molecular and quasi-molecular clusters.

The reaction of [Ni(9)C(CO)(17)](2-) with [Cu(CH(3)CN)(4)][BF(4)] (1.1-1.5 equiv.) afforded the first Ni-Cu carbide carbonyl cluster, i.e., [H(2)Ni(30)C(4)(CO)(34){Cu(CH(3)CN)}(2)](4-) ([H(2)1](4-)). This has been crystallised in a pure form with miscellaneous [NR(4)](+) (R = Me, Et) cations, as well as co-crystallised with [H(2)Ni(29)C(4)(CO)(33){Cu(CH(3)CN)}(2)](4-) ([H(2)2](4-)) which differs from [H(2)1](4-) by a missing Ni(CO) fragment. By increasing the [Cu(CH(3)CN)(4)](+)/[Ni(9)C(CO)(17)](2-) ratio to 1.7-1.8, the closely related [H(2)Ni(30)C(4)(CO)(35){Cu(CH(3)CN)}(2)](2-) ([H(2)3](2-)), [H(2)Ni(29)C(4)(CO)(34){Cu(CH(3)CN)}(2)](2-) ([H(2)4](2-)), and [H(2)Ni(29)C(4)(CO)(32)(CH(3)CN)(2){Cu(CH(3)CN)}(2)](2-) ([H(2)5](2-)) dianions have been obtained. Replacement of Cu-bonded CH(3)CN with p-NCC(6)H(4)CN afforded, after protonation of the tetra-anion, mixtures of [H(3)Ni(30)C(4)(CO)(34){Cu(NCC(6)H(4)CN)}(2)](3-) ([H(3)6](3-)) and [H(3)Ni(29)C(4)(CO)(33){Cu(NCC(6)H(4)CN)}(2)](3-) ([H(3)7](3-)). The species 1-7 display a common Ni(28)C(4)Cu(2) core and differ for the charge, the presence of additional Ni atoms, the number and nature of the ligands, even though they are obtained under similar experimental conditions and often in mixtures. Their nature in solution has been investigated via FT-IR, chemical and electrochemical methods. Electrochemical studies, besides confirming the poly-hydride nature of these clusters, show that they undergo different redox processes with features of chemical reversibility, and this might be taken as proof of the incipient metallisation of their metal cores.

Metal Segregation in Bimetallic CoPd Carbide Carbonyl Clusters: Synthesis, Structure, Reactivity and Electrochemistry of [H6-n Co20 Pd16 C4 (CO)48 ]n- (n=3-6).

Nanometric CoPd bimetallic [H6-n Co20 Pd16 C4 (CO)48 ]n- (n=3-6) tetracarbide carbonyl clusters have been prepared by redox condensation of [Co6 C(CO)15 ]2- with [PdCl2 (Et2 S)2 ]. The crystal structures of both the dihydride tetra-anion and monohydride penta-anion have been determined as their [NEt4 ]4 [H2 Co20 Pd16 C4 (CO)48 ]⋅4 CH3 COCH3 and [NMe3 (CH2 Ph)][NMe4 ]4 [HCo20 Pd16 C4 (CO)48 ]⋅5 CH3 COCH3 salts, respectively. The two species are isostructural and their structures display a perfect segregation of the two metals. They are composed of a cubic close-packed (ccp) Pd16 core stabilised on its surface by four {Co5 C(CO)12 } organometallic fragments. Their polyhydride nature has been corroborated by the study of their reactions with acids and bases, and confirmed by electrochemical studies. In addition, the reactions of [H2 Co20 Pd16 C4 (CO)48 ]4- with Na/naphthalene and PPh3 /CO allowed the isolation of other lower nuclearity homoleptic and heteroleptic clusters, that is, [H6-n Co16 Pd2 C3 (CO)28 ]n- (n=5, 6), [Co4 Pd2 C(CO)11 (PPh3 )2 ], [Co2 Pd5 C(CO)8 (PPh3 )5 ], and [Co4 Pd4 C2 (PPh3 )4 (CO)10 Cl]- . [H6-n Co16 Pd2 C3 (CO)28 ]n- (n=5, 6) represent the first homoleptic metal-carbonyl clusters containing three interstitial carbide atoms.

New high-nuclearity carbonyl and carbonyl-substituted rhodium clusters and their relationships with polyicosahedral carbonyl-substituted palladium- and gold-thiolates.

A reinvestigation of the synthesis of [H(5-n)Rh(13)(CO)(24)](n-) (n = 2, 3) led to isolation of a series of Rh(19), Rh(26), and Rh(33) high-nuclearity carbonyl and carbonyl-substituted rhodium clusters. The [Rh(19)(CO)(31)](5-) (1) is electronically equivalent with [Pt(19)(CO)(22)](4-), but poor crystal diffraction data of all salts obtained to date have prevented its geometrical analysis. The structures of Rh(26)(CO)(29)(CH(3)CN)(11) (2) as 2·2CH(3)CN and [Rh(33)(CO)(47)](5-) (3) as [NEt(4)](5)[3]·Me(2)CO were determined from complete X-ray diffraction determinations. The latter two species adopt polyicosahedral metal frameworks, and notably, [Rh(33)(CO)(47)](5-) represents the molecular group 9 metal carbonyl cluster of highest nuclearity so far reported.

Synthesis, structure, and electrochemistry of the Ni-Au carbonyl cluster [Ni12Au(CO)24]3- and its relation to [Ni32Au6(CO)44]6-.

A detailed study of the reaction between [Ni(6)(CO)(12)](2-) and [AuCl(4)](-) afforded the isolation of the new Ni-Au cluster [Ni(12)Au(CO)(24)](3-) as well as identifying an improved synthesis for the previously reported [Ni(32)Au(6)(CO)(44)](6-). The new [Ni(12)Au(CO)(24)](3-) cluster is composed by two [Ni(6)(CO)(12)](2-) moieties coordinated to a central Au(I) ion, as determined by X-ray diffraction. It is noteworthy that the two [Ni(6)(CO)(12)](2-) fragments display different geometries, i.e., trigonal antiprismatic (distorted octahedral) and distorted trigonal prismatic (monocapped square pyramidal). The chemical reactivity of these clusters and their electrochemical behavior have been studied. [Ni(12)Au(CO)(24)](3-) is irreversibly transformed, upon electrochemical reduction, into Au(0) and [Ni(6)(CO)(12)](2-), followed by the reversible reduction of the latter homometallic cluster. Conversely, [Ni(32)Au(6)(CO)(44)](6-) displays five reductions, with apparent features of reversibility, confirming the ability of larger metal carbonyl clusters to reversibly accept and release electrons.

Surface decorated platinum carbonyl clusters.

Four molecular Pt-carbonyl clusters decorated by Cd-Br fragments, i.e., [Pt(13)(CO)(12){Cd(5)(µ-Br)(5)Br(2)(dmf)(3)}(2)](2-) (1), [Pt(19)(CO)(17){Cd(5)(µ-Br)(5)Br(3)(Me(2)CO)(2)}{Cd(5)(µ-Br)(5)Br(Me(2)CO)(4)}](2-) (2), [H(2)Pt(26)(CO)(20)(CdBr)(12)](8-) (3) and [H(4)Pt(26)(CO)(20)(CdBr)(12)(PtBr)(x)](6-) (4) (x = 0-2), have been obtained from the reactions between [Pt(3n)(CO)(6n)](2-) (n = 2-6) and CdBr(2)·H(2)O in dmf at 120 °C. The structures of these molecular clusters with diameters of 1.5-2 nm have been determined by X-ray crystallography. Both 1 and 2 are composed of icosahedral or bis-icosahedral Pt-CO cores decorated on the surface by Cd-Br motifs, whereas 3 and 4 display a cubic close packed Pt(26)Cd(12) metal frame decorated by CO and Br ligands. An oversimplified and unifying approach to interpret the electron count of these surface decorated platinum carbonyl clusters is suggested, and extended to other low-valent organometallic clusters and Au-thiolate nanoclusters.

Nickel poly-acetylide carbonyl clusters: structural features, bonding and electrochemical behaviour.

The reactions of [NEt(4)](2)[Ni(6)(CO)(12)] with miscellaneous carbon halides (e.g. CCl(4), C(4)Cl(6)) in CH(2)Cl(2) have been extensively investigated particularly focusing on the stoichiometric ratio of the reagents and reaction temperature. This allowed the preparation of the previously known acetylide clusters [Ni(16)(C(2))(2)(CO)(23)](4-), [HNi(25)(C(2))(4)(CO)(32)](3-) and [Ni(22)(C(2))(4)(CO)(28)Cl](3-), as well as isolation and full characterisation of the closely related [Ni(17)(C(2))(2)(CO)(24)](4-) and [Ni(25)(C(2))(4)(CO)(32)](4-) tetraanions. From a structural point of view, all these clusters are based on a Ni(16) square orthobicupola which contain interstitial C(2), Ni(η(2)-C(2))(4) or Ni(2)(µ-η(2)-C(2))(4) moieties, displaying rather short C-C bonds. Electrochemical studies reveal that all these species undergo different redox processes, even if their stability is rather limited. This is corroborated by an extensive analysis of the interaction between interstitial C(2) acetylide units and the metal cluster cage by Extended Huckel Molecular Orbital (EHMO) calculations, which indicates that tightly bonded C-C units are less effective than isolated C-atoms in stabilising the cluster cage.

Electronic stabilization of trigonal bipyramidal clusters: the role of the Sn(II) ions in [Pt5(CO)5{Cl2Sn(µ-OR)SnCl2}3]3- (R = H, Me, Et, iPr).

The new [Pt(5)(CO)(5){Cl(2)Sn(µ-OR)SnCl(2)}(3)](3-) (R = H, Me, Et, (i)Pr; 1-4) clusters contain trigonal bipyramidal (TBP) Pt(5)(CO)(5) cores, as certified by the X-ray structures of [Na(CH(3)CN)(5)][NBu(4)](2)[1]·2CH(3)CN and [PPh(4)](3)[4]·3CH(3)COCH(3). The TBP geometry, which is rare for group 10 metals, is supported by an unprecedented interpenetration with a nonbonded trigonal prism of tin atoms. By capping all the Pt(3) faces, the Sn(II) lone pairs account for both Sn-Pt and Pt-Pt bonding, as indicated by DFT and topological wave function studies. In the TBP interactions, the metals use their vacant s and p orbitals using the electrons provided by Sn atoms, hence mimicking the electronic picture of main group analogues, which obey the Wade's rule. Other metal TBP clusters with the same total electron count (TEC) of 72 are different because the skeletal bonding is largely contributed by d-d interactions (e.g., [Os(5)(CO)(14)(PR(3))(µ-H)(n)](n-2), n = 0, 1, 2). In 1-4, fully occupied d shells at the Pt(ax) atoms exert a residual nucleophilicity toward the adjacent main group Sn(II) ions permitting their hypervalency through unsual metal donation.

Icosahedral Pt-centered Pt13 and Pt19 carbonyl clusters decorated by [Cd5(µ-Br)5Br(5-x)(solvent)x]x+ rings reminiscent of the decoration of Au-Fe-CO and Au-thiolate nanoclusters: a unifying approach to their electron counts.

The new [Pt(13)(CO)(12){Cd(5)(µ-Br)(5)Br(2)(dmf)(3)}(2)](2-) and [Pt(19)(CO)(17){Cd(5)(µ-Br)(5)Br(3)(Me(2)CO)(2)}{Cd(5)(µ-Br)(5)Br(Me(2)CO)(4)}](2-) clusters have been obtained in good yields by reaction of [Pt(12)(CO)(24)](2-) with CdBr(2)·H(2)O in dmf at 90 °C and structurally characterized by X-ray diffraction. Their structures consist of a Pt-centered Pt(13)(CO)(12) icosahedron and a Pt(19)(CO)(17) interpenetrated double icosahedron, respectively, decorated by two Cd(5)(µ-Br)(5)Br(5-x)(solvent)(x) rings. Their surface decoration may be related to that of Au-Fe-CO clusters as well as to the staple motifs stabilizing gold-thiolates nanoclusters. An oversimplified and unifying approach to interpret their electron count is suggested.

Synthesis, structure, and spectroscopic characterization of [H(8-n)Rh22(CO)35](n-) (n = 4, 5) and [H2Rh13(CO)24{Cu(MeCN)}2](-) clusters: assessment of CV and DPV as techniques to circumstantiate the presence of elusive hydride atoms.

The previously ill-characterized [H(x)Rh(22)(CO)(35)](4-/5-) carbonyl cluster has been obtained as a byproduct of the synthesis of [H(3)Rh(13)(CO)(24)](2-) and effectively separated by metathesis of their sodium salts with [NEt(4)]Cl. Although the yields are modest and never exceed 10-15% (based on Rh), this procedure affords spectroscopically pure [H(3)Rh(22)(CO)(35)](5-) anion. Formation of the latter in mixture with other Rh clusters was also observed by electrospray ionization-mass spectrometry (ESI-MS) in the oxidation of [H(2)Rh(13)(CO)(24)](3-) with Cu(2+) salts. The recovery of further amounts of [H(3)Rh(22)(CO)(35)](5-) was hampered by too similar solubility of the salts composing the mixture. Conversely, the reaction in CH(3)CN of [H(2)Rh(13)(CO)(24)](3-) with [Cu(MeCN)(4)](+)[BF(4)](-) leads to the [H(2)Rh(13)(CO)(24){Cu(MeCN)}(2)](-) bimetallic cluster. The X-ray crystal structures of [H(4)Rh(22)(CO)(35)](4-), [H(3)Rh(22)(CO)(35)](5-), and [H(2)Rh(13)(CO)(24){Cu(MeCN)}(2)](-) are reported. From a formal point of view, the metal frame of the former two species can be derived by interpenetration along two orthogonal axes of two moieties displaying the structure of the latter. The availability of [H(8-n)Rh(22)(CO)(35)](n-) salts prompted their detailed chemical, spectroscopic, and electrochemical characterization. The presence of hydride atoms has been directly proved both by ESI-MS and (1)H NMR. Moreover, both [H(4)Rh(22)(CO)(35)](4-) and [H(3)Rh(22)(CO)(35)](5-) undergo distinctive electrochemically reversible redox changes. This allows to assess electrochemical studies as indisputable though circumstantial evidence of the presence of (1)H NMR-silent hydride atoms in isostructural anions of different charge.

Self-assembly of [Pt(3n)(CO)(6n)]2- (n = 4-8) carbonyl clusters: from molecules to conducting molecular metal wires.

A comprehensive study discussing the different parameters that influence the self-assembly of [Pt(3n)(CO)(6n)](2-) (n = 4-8) clusters with miscellaneous mono- and dications into 0-D, 1-D, 2-D, and 3-D materials is herein reported. As an unexpected bonus, the use of Ru(II) dications allowed the first structural characterization of the previously unknown [Pt(21)(CO)(42)](2-) dianion. 0-D structures, which contain isolated ions, are electrical insulators in solid form. Conversely, as soon as infinite chains of clusters are formed, the electrical resistivity, measured in pressed pellets, decreases to 10(5)-10(6), 10(4), and 10(2) ohms cm for discontinuous, semicontinuous, and continuous chains, respectively. Therefore, the resemblance of these materials to molecular metal wires is not only morphological but also functional. Preliminary results of possible self-assembly phenomena in a solution of [Pt(15)(CO)(30)](2-) and [Pt(18)(CO)(36)](2-) according to dynamic light scattering experiments are also reported.

Magnetic behavior of odd- and even-electron metal carbonyl clusters: the case study of [Co(8)Pt(4)C(2)(CO)(24)](n-) (n = 1, 2) carbide cluster.

The reaction of [Co(6)C(CO)(15)](2-) with 2 equiv of PtCl(2)(Et(2)S)(2) affords the new heterobimetallic [Co(8)Pt(4)C(2)(CO)(24)](2-), [1](2-), carbonyl cluster. [1](2-) undergoes reversible chemical and electrochemical oxidation and reduction processes disclosing a complete series of [1](n-) (n = 1-4) clusters. The mono- and dianion of [1](n-) have been isolated as their tetra-substituted ammonium salts and fully characterized by means of IR, (13)C NMR, ESI-MS, and X-ray crystallography. Variable-temperature (VT) solid-state EPR studies on pure crystalline samples indicate that both [1](2-) and [1](-*) are paramagnetic, due to a doublet state of the latter and a triplet state of [1](2-). This conclusion is supported by SQUID measurements on the same crystalline sample of [1](2-). The present study indisputably demonstrates that even-electron transition metal carbonyl clusters (TMCC) can be magnetic.