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Thermolysisof [(Cp*RuCO)2B2H6] (1; Cp* = η5-C5Me5) with [Ru3(CO)12] yielded the trimetallaborane[(Cp*RuCO)3(μ3-H)BH] (2)and a number of homometallic boride clusters: [Cp*RuCO{Ru(CO)3}4B] (3), [(Cp*Ru)2{Ru2(CO)8}BH] (4), and [(Cp*Ru)2{Ru4(CO)12}BH] (5). Compound 2is isoelectronic and isostructural with the triply bridgedborylene compounds [(μ3-BH)(Cp*RuCO)2(μ-CO){Fe(CO)3}] (6) and [(μ3-BH)(Cp*RuCO)2(μ-H)(μ-CO){Mn(CO)3}] (7), where the [μ3-BH] moiety occupies the apicalposition. To test if compound 2undergoes hydroborationreactions with alkynes, as observed with 6, we performedthe reaction of 2with the same set of alkynes underphotolytic conditions. However, neither 2nor 7undergoes hydroboration to yield a vinyl–borylene complex.On the other hand, thermolysis of 6with trimethylsilylethyleneyielded the novel diruthenacarborane [1,1,7,7,7-(CO)5-2,3-(Cp*)2-μ-2,3-(CO)-μ3-1,2,3-(CO)-5-(SiMe3)-pileo-1,7,2,3,4,5-Fe2Ru2C2BH] (8). The solid-state X-ray diffractionresults suggest that 8exhibits a pentagonal -bipyramidalgeometry with one additional CO capping one of its faces. Cluster 3is a boride cluster where boron is in the interstitial positionof a square-pyramidal geometry, whereas compound 4canbe described as a tetraruthenium boride in which the Ru4butterfly skeleton has an interstitial boron atom. Electronic structurecalculations of compound 2employing density functionaltheory (DFT) generate geometries in agreement with the structure determinations.The existence of a large HOMO–LUMO gap in 2isin agreement with its high stability. Bonding patterns in the structurehave been analyzed on the grounds of DFT calculations. Furthermore,the B3LYP-computed 11B and 1H chemical shiftsfor compound 2precisely follow the experimentally measuredvalues. All the compounds have been characterized by IR and 1H, 11B, and 13C NMR spectroscopy, and the geometriesof the structures were unambiguously established by crystallographicanalyses of 2–4and 8. [ABSTRACT FROM AUTHOR]

We present the results of our investigation of a thermally driven cluster expansion of rhodaborane systems with BH₃-THF. Four novel rhodaborane clusters, for example, nido-[(Cp*Rh)₂B₆H10], 1; nido-[(Cp*Rh)B⁸H13], 2; nido-[(Cp*Rh)2-B⁷H12], 3; and mdo-[(Cp*Rh)₃B⁷H⁸], 4 (Cp* = η⁵-C₅Me₅), have been isolated from the thermolysis of [Cp*RhCl₂]₂ and borane reagents in modest yields. Rhodaborane 1 has a nido geometry and is isostructural with [B⁷H12]. The low temperature "B and 'H NMR data demonstrate that compound 1 exists in two isomeric forms. The framework geometry of 2 and 3 is similar to that of [B10H14] with one BH group in 2 (3-position), and two BH groups in 3 (3, 4-positions) are replaced by an isolobal {Cp*Rh} fragment. The 11 vertex cluster 4 has a nido structure based on the 12 vertex icosahedron, having three rhodium and eight boron atoms. In addition, the reaction of rhodaborane 1 with [Fe₂(CO)⁷] yielded a condensed cluster [(Cp*Rh)₂{Fe(CO)₃}₂B₆H10], 5. The geometry of 5 consists of [Fe₂B₂] tetrahedron and an open structure of [(Cp*Rh)₂B₆], fused through two boron atoms. The accuracy of these results in each case is established experimentally by spectroscopic characterization in solution and structure determinations in the solid state. [ABSTRACT FROM AUTHOR]

Abstract: The reactivity of two isoelectronic and isostructural metallaboranes, nido-[(Cp*Rh)2B6H10], 1 and nido-[(Cp*Ru)2B6H12], 2 with alkynes demonstrates that a change in metal from group 9 to group 8 creates difference in the reactivity pattern. Compound 1 catalyzes the cyclotrimerization of a variety of internal and terminal alkynes to yield 1,3,5- and 1,2,4-substituted benzene. In contrast, compound 2 shows no reactivity toward alkynes. A set of alkynes have been verified with nido-1 that yielded several benzene derivatives in satisfactory yields. [Copyright &y& Elsevier]

Recent years have witnessed rapid advances in the field of BN/CC isosterism, particularly in the case of azaborinines. Examples of each isomer have now been synthesized and characterized. This review provides a survey of the latest methods for the synthesis of new monocyclic B,N heterocycles, their reactivities, and potential applications in biomedical and materials science. [ABSTRACT FROM AUTHOR]

Abstract: Mild thermolysis of arachno-[(Cp*RuCO)2B2H6], 1 in presence of GeCl2·dioxane yielded di-μ-germylene complex [(Cp*Ru)2(μ-GeCl2)2(CO)2], 2 (Cp* = η5-C5Me5). The molecular structure of 2 exhibits a diruthenium unit bridged by a pair of μ-GeCl2 moieties. The Cp* and the terminal CO ligands are oriented in anti fashion with respect to Ru–Ru bond. In addition, the reaction of 2 with arachno-[CpFe(CO)B3H8] (Cp = η5-C5H5) transformed to germenocene, [Cp2Ge:], 3 via an unstable intermediate [CpFe(CO)B2H5GeCl2], I. The 11B NMR spectroscopy was used as a tool to establish a probable reaction pathway for the formation of germenocene 3. Cluster 2 has been characterized by IR and NMR spectroscopy, and the geometric structure was unequivocally established by crystallographic analysis. [Copyright &y& Elsevier]

The Cover Feature shows a range of interesting boron‐containing compounds that have emerged over the years. The central focus is on the family of azaborinines, upon which our Microreview in this issue is based. Azaborinines, BN analogues of benzene, come in three forms depending on the relative position of the B and N atoms, as depicted on the central watch face. More information can be found in the Microreview by H. Braunschweig et al. [ABSTRACT FROM AUTHOR]