A Triruthenium Complex Capped by a Triply Bridging Oxoboryl Ligand

Electrochemical atomic force microscopy of two-dimensional trinuclear ruthenium clusters molecular assembly and dynamics under redox state control

Mixed-valence ruthenium trinuclear clusters containing dichloroacetates were synthesized, and the self-assembly of a single molecular adlayer composed of these clusters on a graphite surface was investigated by atomic force microscopy (AFM). AFM clearly revealed the dynamics of two-dimensional (2D) structure formation as well as the molecular characteristics of the adlayers at different electrochemical interfaces. The results verified that the design of metal complexes is important not only for redox chemistry but also for molecular assembly and nanoarchitecture construction.

Structural Trends in Monoboronyl Compounds: Analysis of the Interaction of Second-Row Elements with BO

A theoretical study of the monoboronyl compounds of second-row elements, [XBO] (X = Na, Si, P, S, Cl), has been carried out. It is observed that the preference for the XBO arrangement is higher when moving to the right of the period. In the case of sodium monoboronyl three minima were characterized, all lying rather close in energy: linear NaBO, linear NaOB, and an L-shaped structure. Linear NaBO and the L-shaped structure are nearly isoenergetic, whereas linear NaOB is located 2.11 kcal/mol above linear NaBO. The barrier for the conversion of the L-shaped structure into linear NaBO is about 5.1 kcal/mol, suggesting that both species could be potential targets for experimental detection. For silicon monoboronyl, two minima, linear SiBO and linear SiOB, are found, the latter lying about 13 kcal/mol above SiBO. The barrier for the isomerization of SiOB into SiBO is estimated to be 11.4 kcal/mol. For phosphorus, sulfur, and chlorine monoboronyls the linear XBO isomer is clearly the most stable one, and the barriers for the conversion into XOB species are relatively high, suggesting that quite likely the linear XBO isomer should be the main experimental target. All studied monoboronyls are relatively stable, with dissociation energies increasing from left to right of the second-row (69.8 kcal/mol for NaBO and 118.98 kcal/mol for ClBO). An analysis of the bonding for second-row monoboronyls has been carried out, emphasizing the different characteristics of the X-B and X-O bonds along the second row.

Pathways to the polymerization of boron monoxide dimer to give low-density porous materials containing six-membered boroxine rings

Density functional theory has been used to examine the key mechanistic details of the polymerization of boron monoxide (BO) via its O≡B-B≡O dimer to give ultimately low-density porous polymeric (BO)n materials. The structures of such materials consist of planar layers of six-membered boroxine (B3O3) rings linked by boron-boron bonds. Initial cyclooligomerization of B2O2 leads to a B4O4 dimer with a four-membered B2O2 ring, a B6O6 trimer containing a six-membered B3O3 (boroxine) ring, a B8O8 tetramer containing an eight-membered B4O4 ring, and even a B10O10 pentamer containing a ten-membered B5O5 ring. However, an isomeric B10O10 structure containing two boroxine rings linked by a B-B bond is a much lower energy structure by ∼31 kcal/mol owing to the special stability of the aromatic boroxine rings. Rotation of the boroxine rings around the central B-B bond in this B10O10 structure has a low rotation barrier suggesting that further oligomerization to give products containing either perpendicular or planar orientations of the B3O3 rings is possible. However, the planar oligomers are energetically more favorable since they have fewer high-energy external BO groups bonded to the network of boroxine rings. The pendant boronyl groups are reactive sites that can be used for further polymerization. Mechanistic aspects of the further oligomerization of (BO)x systems to give a B24O24 oligomer with a naphthalene-like arrangement of boroxine rings and a B84O84 structure with a coronene-like arrangement of boroxine rings have been examined. Further polymerization of these intermediates by similar processes is predicted to lead ultimately to polymers consisting of planar networks of boroxine rings. The holes between the boroxine rings in such polymers suggests that they will be porous low-density materials. Applications of such materials as absorbents for small molecules are anticipated.

The siliconyl, boronyl, and iminoboryl ligands as analogues of the well-known carbonyl ligand: predicted reactivity towards dipolar cyclooligomerization in iron/cobalt carbonyl complexes

The Fe(CO)₄(SiO), Co(CO)₄(BO), and Co(CO)₄(BNSiMe₃), complexes akin to the well-known Fe(CO)₅ are predicted by density functional theory to undergo exothermic oligomerization to give the oligomers containing Si_nO_n/B_nO_n/B₂N₂ rings with single bonds.