Infinite Molecular {[Pt_3n(CO)_6n]^2–}_∞ Conductor Wires by Self‐Assembly of [Pt_3n(CO)_6n]^2– (n = 5–8) Cluster Dianions Formally Resembling CO‐Sheathed Three‐Platinum Cables

Abstract

Miscellaneous tetrasubstituted ammonium salts of [Pt 3n -(CO) 6n ]2-(n = 5-8) clusters, obtained by the stoichiometric oxidation of the corresponding [Pt 9 (CO) 18 ] 2-salts with tropylium tetrafluoroborate, self-assemble into infinite semicontinuous or continuous {[Pt 3n (CO) 3n (µ-CO) 3n ] 2-} ϱ conductor wiresOne dimensional molecular metal wires [1,2] and one-and two-dimensional superclusters that are assembled through M-M bonds [3,4] are interesting as low-dimensional molecular materials, and they may find applications in molecular electronics and nanolithography. [5][6][7] According to EHMO calculations, the LUMO of a Pt 3 (CO) 3 (µ-CO) 3 triangular moiety involves the combination of cyclopropenyl-like inphase Pt p z atomic orbitals. [8,9] For an infinite stack of neutral Pt 3 (CO) 3 (µ-CO) 3 or dianionic [Pt 3 (CO) 3 (µ-CO) 3 ] 2-moieties, the σMO band, which is generated along the C 3 axis by the cyclopropenyl-like MOs, should be empty or completely filled, respectively. Therefore, such a stack should not be stable. However, in the case where the stack is generated by the assembly of [Pt 3n (CO) 6n ] 2-(n Ͼ 1) cluster dianions, the above MO band would only be 1/n filled; therefore, the stack could be feasible and may behave as a conducting molecular wire.The first hint of a possible strategy that might favor selfassembly of [Pt 3n (CO) 2-dianions, it appeared more appropriate to substitute r -with the length of the dianion (L), and consequently, to replace r + by the diameter of the cation (D), and to use the L/D ratio as a rough guideline to achieve self-assembly of the dianions. In particular, it was speculated that a high L/D ratio would imply a great difference between the sizes of the dianion and the cation and a decreased repulsion between the dianions; the constant 2-charge would be delocalized over an increasing number of Pt 3 (CO) 6 units. Furthermore, in the case of self-assembly of continuous [Pt 3n (CO) 6n ] 2-stacks, L would also determine the amount of filling of the σMO band that develops along the C 3 axis.We have, therefore, reinvestigated the synthesis and structures of miscellaneous [NR 4 ] 2 [Pt 3n (CO) 6n ] salts to assess the effect of the L/D ratio on self-assembly. We report here some significant structural results, as well as preliminary resistivity measurements of the above salts, which point out that stacking of [Pt 3n (CO) 6n ] 2-dianions leads to conducting molecular wires.The investigated salts are collected in 2-salt [13] with tropylium tetrafluoroborate and crystallized from THF/toluene or acetone/2-propanol mixtures. The formulas of miscellaneous salts were established

Small Adsorbate‐Assisted Shape Control of Pd and Pt Nanocrystals

“…Many metallic Pd and Pt nanoclusters are able to crystallize into single crystals for total structure determinations. [113][114][115][116][117][118][119][120] Nanocluster chemistry could provide us important information on the adsorption structure of small adsorbates on the metal surface as well as the structure of nanocrystals at the very beginning of the control process. In the synthesis of nanocrystals, such information is usually hard to be acquired but critical to deeply understand how small adsorbates control the formation of nanocrystals.…”

Monomeric Chini‐Type Triplatinum Clusters Featuring Dianionic and Radical‐Anionic π*‐Systems

“…[3][4][5][6] With regard to topology and electronic structure,o ne of the most intriguing classes of such complexes are the so-called "Chini clusters," [Pt 3 (CO) 6 ] n 2À . [9][10][11] Many of the higher ordered structures display remarkable conductive properties,l eading to interest in their use as tunable conductive materials based off of am olecular platform. [9][10][11] Many of the higher ordered structures display remarkable conductive properties,l eading to interest in their use as tunable conductive materials based off of am olecular platform.…”

“…[9][10][11] Many of the higher ordered structures display remarkable conductive properties,l eading to interest in their use as tunable conductive materials based off of am olecular platform. [14] While the oligomeric members of [Pt 3 (CO) 6 ] n 2À with n = 2-8 have all been isolated and structurally characterized, [7][8][9][10][11]15] the parent species [Pt 3 (CO) 6 ] 2À (n = 1) has eluded complete characterization. [14] While the oligomeric members of [Pt 3 (CO) 6 ] n 2À with n = 2-8 have all been isolated and structurally characterized, [7][8][9][10][11]15] the parent species [Pt 3 (CO) 6 ] 2À (n = 1) has eluded complete characterization.…”

“…[6][7][8] In these clusters, triangulo-Pt 3 units bearing both terminal and bridging carbonyl ligands stack one on top of the other along ac ommon C 3 axis to form columnar structures bearing an overall doubly anionic charge.T he higher nuclearity oligomers (n = 5-8) can self-assemble into continuous chains,w ith the dimensionality of long-range ordering being highly dependent upon the identity of the charge-balancing cations. [9][10][11] Many of the higher ordered structures display remarkable conductive properties,l eading to interest in their use as tunable conductive materials based off of am olecular platform. [12,13] As such, af urthered understanding of the electronic structure and reactivity profiles available to these clusters continues to be of importance.…”

“…[12,13] As such, af urthered understanding of the electronic structure and reactivity profiles available to these clusters continues to be of importance. [14] While the oligomeric members of [Pt 3 (CO) 6 ] n 2À with n = 2-8 have all been isolated and structurally characterized, [7][8][9][10][11]15] the parent species [Pt 3 (CO) 6 ] 2À (n = 1) has eluded complete characterization. Although reportedly synthesized in situ via reduction of [Pt 3 (CO) 6 ] 2 2À with Na/K alloy, it could not be crystallized or precipitated from solution, with characterization relying solely upon IR and atomic absorption spectroscopies.Interestingly,a lthough several mixed carbonyl/phosphine clusters of the type Pt 3 (m-CO) 3 (PR 3 ) 3 have been long-known, [16][17][18][19][20] their reduction to the corresponding platinates has not been reported, potentially implying that the weak p-accepting properties of triorganophosphines are insufficient to stabilize the presence of two negative charge equivalents.…”