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A series of novel isocloso-diiridaboranes [(Cp*Ir)2B6H6], 1, 2; [1,7-(Cp*Ir)2B8H8], 4; [1,4-(Cp*Ir)2B8H8], 5; [(Cp*Ir)2B9H9], 8; isonido-[(Cp*Ir)2B7H7], 3; and 10-vertex cluster [5,7-(Cp*Ir)2B8H12], 6 (Cp* = η5-C5Me5) have been isolated and structurally characterized from the pyrolysis of [Cp*IrCl2]2 and BH3·thf. On the other hand, the corresponding rhodium system afforded 10- and 11-vertices clusters [5-(Cp*Rh)B9H13)], 7, and [(Cp*Rh)2B9H9], 9, respectively. Clusters 1 and 2 are topological isomers. The geometry of 1 is dodecahedral, similar to that of its parent borane [B8H8]2-, in which two of the [BH] vertices are replaced by two [Cp*Ir] fragments. The geometry of 2 can be derived from a nine-vertex tricapped trigonal prism by removing one of the capped vertices. Compounds 4 and 5 are 10-vertex isocloso clusters based on a 10-vertex bicapped square antiprism structure. The only difference between them is the presence of a metal-metal bond in 5. The solid-state structures of 8 and 9 attain an 11-vertex geometry in which a unique six-membered B6H6 moiety is bonded to the metal center. In addition, quantum-chemical calculations have been used to provide further insight into the electronic structure and stability of the clusters. All the compounds have been characterized by IR and ¹H, 11B, and 13C NMR spectroscopy in solution, and the solid-state structures were established by X-ray crystallographic analysis. [ABSTRACT FROM AUTHOR]

This work describes the synthesis, structural characterizations, and electronic structures of a series of novel homometallic cubane clusters [(Cp*Ru)2{Ru(CO)2}2BH(μ3-E)(μ-H)B(μ-H)3M], (2, M = Cp*Ru, E = CO; 3, M = Ru(Cp*Ru)2(μ-CO)3(μ-H)BH), E = BH), [(Cp*Ru)3(μ3-CO)(BH)3(μ3-H)3], 4, and [(Cp*Ru)2(μ3-CO){Ru(CO)3}2(BH)2(μ-H)B], 5 (Cp* = η5-C5Me5). These cubane clusters have been isolated from a thermally driven reaction of diruthenium analogue of pentaborane(9) [(Cp*RuH)2B3H7], 1, and [Ru3(CO)12]. Structural and spectroscopic studies revealed the existence of triply bridged hydrogen (μ3-H) atoms that participate as a vertex in the cubane core formation for compounds 2, 3, and 4. In addition, the crystal structure of these clusters clearly confirms the presence of an electron precise borane ligand (borylene fragment) which is triply bridged to the trimetallic units. Bonding of these novel complexes has been studied computationally by DFT methods, and the studies demonstrate that the cubane clusters 2 and 3 possess 60 cluster valence electrons (cves) with six metal-metal bonds. All the new compounds have been characterized in solution by mass spectrometry; IR; and ¹H, 11B, and 13C NMR studies, and the structural types were unequivocally established by crystallographic analysis of compounds 2-5. [ABSTRACT FROM AUTHOR]

The first example of a homometallic neutral zirconaborane, [(Cp2Zr)2B5H11], 1, has been prepared through the thermolysis of [Cp2Zr(BH4)2], generated from the fast metathesis reaction of [Cp2ZrCl2] and LiBH4·thf with BH3·thf. The solid-state structure of 1 shows an open geometry with a planar B3 ring. The bonding between the Zr center and the central B3 ring was studied computationally by DFT methods, and based on the combined experimental and computational results compound 1 can be defined as a metal-stabilized arachno-B3H9. Further, in an attempt to synthesize a hybrid analogue of 1 by introducing two electron fragments into arachno-[(Cp2Zr)(Cp*Ir)B4H10], 2, we have performed the reaction of 2 with [Ru3(CO)12]. However, the reaction led to the formation of a hybrid metallaborane, [(Cp*Ir){Ru3(CO)8}B4H10], 3. [ABSTRACT FROM AUTHOR]

Metal assisted borane condensationmethod has been employed forthe preparation of novel metallaborane cluster containing group 4metal. Pyrolysis of [Cp*IrB3H9], 1, with in situ generated zirconium bisborohydrate [Cp2Zr(BH4)2], produced from the fast metathesisreaction of [Cp2ZrCl2] and LiBH4,and excess of BH3·THF yielded arachno-[(Cp2Zr)(Cp*Ir)B4H10], 2, in 56% yield. Compound 2constitutes the first crystallographicstructure determination of hexaborane(12) metal analogue containingzirconium. The observed geometry of 2can be generatedfrom a dodecahedron by removing two vertices and an edge. Anticipatinga straight metal fragment substitution/addition reaction, mild thermolysisof 2with [Fe2(CO)9] was carriedout. However, the reaction led to the formation of known trimetallic[Cp*IrFe2(CO)9] cluster via cluster degradation.In addition, density functional theory (DFT) calculations have beencarried out for 2and other hypothetical early–latecombinations of hexaborane(12) metal analogues to reveal the electronicstructures. [ABSTRACT FROM AUTHOR]

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]

The preparation, characterization, and electronic structure of the first heterometallic μ9-boride cluster [(Cp*Rh)2{Co6(CO)I2}(μ-H)(BH)B)] has been reported. The interstitial boron atom in the title cluster is within the bonding contact of eight metal and one boron atom in a unique tricapped trigonal prism geometry. [ABSTRACT FROM AUTHOR]

We report the synthesis and characterization of bis(diiminate)-supported tricoordinated zinc complexes ( 1-4 ) and demonstrate the catalytic activity of one representative compound in the hydroboration of nitriles and carbodiimides using pinacolborane (HBpin). Experimental and theoretical studies were performed to elucidate the reaction mechanism. Our findings indicate that the hydroboration reaction initiates with the formation of a tricoordinated zinc hydride intermediate, followed by the subsequent attack of nitriles and carbodiimides. This leads to the formation of a four-membered metallacycle before the release of the diborylated amine. This work provides access to new types of zinc complexes and highlights its effectiveness in the hydroboration of nitriles and carbodiimides, offering a milder alternative to existing reduction methods., Competing Interests: The authors declare no competing financial interest., (© 2025 The Authors. Published by American Chemical Society.)

Syntheses and structural characterization of supraicosahedral rhodaborane clusters are reported. Reaction of [(Cp*RhCl2)2], (Cp* = η(5)-C5Me5) with [LiBH4·thf] followed by thermolysis with excess of [BH3·thf] afforded 16-vertex closo-[(Cp*Rh)3B12H12Rh{Cp*RhB4H9}], 1, 15-vertex [(Cp*Rh)2B13H13], 2, 12-vertex [(Cp*Rh)2B10Hn(OH)m], (3a: n = 12, m = 0; 3b: n = 9, m = 1; 3c: n = 8, m = 2) and 10-vertex [(Cp*Rh)3B7H7], 4, and [(Cp*Rh)4B6H6], 5. Cluster 1 is the unprecedented 16-vertex cluster, consists of a sixteen-vertex {Rh4B12} with an exo-polyhedral {RhB4} moiety. Cluster 2 is the first example of a carbon free 15-vertex supraicosahedral metallaborane, exhibits icosihexahedron geometry (26 triangular faces) with three degree-six vertices. Clusters 3a-c have 12-vertex isocloso geometry, different from that of icosahedral one. Clusters 4 and 5 are attributed to the 10-vertex isocloso geometry based on 10-vertex bicapped square antiprism structure. In addition, quantum-chemical calculations with DFT methods at the BP86 level of theory have been used to provide further insight into the electronic structure and stability of the optimized structures which are in satisfactory agreement with the structure determinations. All the compounds have been characterized by IR, (1)H, (11)B, (13)C NMR spectroscopy in solution, and the solid state structures were established by crystallographic analysis of compounds 1-5.