Metal-rich metallaboranes: An exo-Fe(CO)3 moiety linked to a cubane core is the most prominent feature of complexes [(Cp*M) 2(μ3-E)2B2H(μ-H){Fe(CO) 2}2Fe(CO)3] (M=Mo, E=S, Se; M=Ru, E=CO; Cp*=n5-C5Me5), which are the first heterobimetallic cubane-type clusters with a boride unit (see structure). © 2011 WILEY-VCH Verlag GmbH &amp; Co. KGaA, Weinheim.

Sundargopal Ghosh

Department Of Chemistry

Cluster compounds

HETEROBIMETALLICS

Heterometallics

Metallaboranes

PROMINENT FEATURES

Borides

Metallic compounds

Molybdenum

ruthenium

selenium

Selenium compounds

Iron compounds

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IIT Madras

Angewandte Chemie - International Edition

Room-temperature reactions between [Cp*CoCl]2 (Cp∗ = ν5-C5Me5) and large excess of [BH2E3]Li (E = S or Se) led to the formation of homocubane derivatives, 1-7. These species are bimetallic tetrahomocubane, [(Cp*Co)2(μ-S)4(μ3-S)4B2H2], 1; bimetallic trishomocubane isomers, [(Cp*Co)2(μ-S)3(μ3-S)4B2H2], 2 and 3; monometallic trishomocubanes, [M(μ-E)3(μ3-E)4B3H3] [4: M = Cp*Co, E = S; 5: M = Cp*Co, E = Se and 6: M = {(Cp*Co)2(μ-H)(μ3-Se)2}Co, E = Se], and bimetallic homocubane, [(Cp*Co)2(μ-Se)(μ3-Se)4B2H2], 7. As per our knowledge, 1 is the first isolated and structurally characterized parent prototype of the 1,2,2′,4 isomer of tetrahomocubane, while 3, 4, and 5 are the analogues of parent D3-trishomocubane. Compounds 2 and 3 are the structural isomers in which the positions of the μ-S ligands in the trishomocubane framework are altered. Compound 6 is an example of a unique vertex-fused trishomocubane derivative, in which the D3-trishomocubane [Co(μ-Se)3(μ3-Se)4B3H3] moiety is fused with an exopolyhedral trigonal bipyramid (tbp) moiety [(Cp*Co)2(μ-H)(μ3-Se)2}Co]. Multinuclear NMR and infrared spectroscopy, mass spectrometry, and single crystal X-ray diffraction analyses were employed to characterize all the compounds in solution. Bonding in these homocubane analogues has been elucidated computationally by density functional theory methods. © 2019 American Chemical Society.

Fulltext

ACS Omega

Homocubane Chemistry: Synthesis and Structures of Mono- And Dicobaltaheteroborane Analogues of Tris- And Tetrahomocubanes

In an effort to synthesize metallaheteroborane complexes of ruthenium, we carried out the reaction of ruthenium methanedithiolate complex, [(Cp∗Ru)2(B3H8)(CS2H)], (Cp∗ = η5-C5Me5) 1 with [BH3SPh]Li at elevated temperature that yielded a dinuclear bridged thiolate complex [Cp∗Ru(µ-SPh)2(µ-η1-S2)RuCp∗], 2. In a similar fashion, reaction of [Cp∗IrCl2]2 with [BH3TePh]Li yielded tellurolato-bridged diiridium half sandwich complex [Cp∗IrH(µ-TePh)2HIrCp∗], 5. All the compounds have been characterized by various spectroscopic techniques and the structures were unequivocally established by crystallographic analysis. Further, the density functional theory (DFT) calculations were performed to investigate the bonding and electronic properties of 2′ and 5′ (Cp analogues of 2 and 5). © 2018

Inorganica Chimica Acta

Chalcogenolato-bridged dinuclear half sandwich complexes of ruthenium and iridium

In an attempt to synthesize expanded-cage metallaheteroboranes containing heavier chalcogen atoms, the reaction of diruthenaborane analogue of pentaborane(9), nido-[1,2-(Cp*RuH)2B3H7] (1) with phenyl-chalcogenoborates Li[BH3(EPh)] (E = S, Se or Te) was carried out. Thermolysis of nido-1 with Li[BH3(SPh)] led to the formation of the dimetalla-pentaborane(11) analogue arachno-[(Cp*Ru)2B3H8(SPh)] (2). In parallel to the formation of 2, the reaction also yielded three B-H functionalized compounds, namely [(Cp*Ru)2B4H7(Ph)] (3), [(Cp*Ru)2B4H7(Cl)] (4) and [(Cp*Ru)2B4H6(SPh)(Cl)] (5). On the other hand, reaction of 1 with Li[BH3(SePh)] led to the formation of the diruthenium analogue of hexaborane(10) nido-[(Cp*Ru)2B4H9(SePh)] (6), whereas Li[BH3(TePh)] yielded the capped nido-pentagonal-pyramidal [(Cp*Ru)2B4H6Te] (7). Compound 7 is a rare ruthenaborane cluster containing a heavier chalcogen element (Te). All the compounds were characterized by mass spectrometry and 1H, 1H{11B}, 11B{1H} and 13C{1H}NMR spectroscopy. The solid state X-ray structures of all the compounds were unequivocally established by crystallographic analysis. Additionally, the electronic properties of compound 2 were analyzed. © 2017 Elsevier B.V.

Journal of Organometallic Chemistry

Synthesis and characterization of diruthenaborane analogues of pentaborane(11) and hexaborane(10)

To build upon our earlier results of heterometallic metallaboranes employing metal carbonyls, we performed the reaction of nido-[(Cp*Rh)2B3H7] (1) (nido-1) with [M(CO)5·THF] (M = Mo or W) that yielded the trimetallic metallaborane clusters [(Cp*Rh)2M(CO)3(μ-CO)(μ3-BH)(B2H4)] (3: M = Mo; 4: M = W) having a capped borylene fragment and trimetallic triply bridging borylene complexes [(Cp*Rh)2(μ3-BH)(μ-CO)M(CO)5] (5: M = Mo; 6: M = W). The chemistry of trimetallic triply bridging borylene complexes (5 and 6) were explored with Lewis bases such as tert-butyl isocyanide and bisphosphine ligands. Photolysis of 5 and 6 with tert-butyl isocyanide yielded [(Cp*Rh)2(μ3-BH)(μ-CO)M(CO)4(CN-tBu)] (7: M = Mo; 8: M = W) and with phosphines, PPh2(CH2)nPPh2 (n = 1, 2) they resulted in the formation of [(Cp*Rh)2(μ3-BH)(μ-CO)M(CO)4((PPh2)2(CH2)n)] (9: n = 1, M = Mo; 10: n = 1, M = W; 11: n = 2, M = Mo; 12: n = 2, M = W). All the new compounds have been characterized in solution by mass spectrometry and NMR spectroscopic techniques. The structural aspects were unambiguously established by X-ray crystallographic analysis of 3–4 and 7–10. © 2018 Elsevier B.V.

Synthesis and ligand substitution of tri-metallic triply bridging borylene complexes

Reactivity of [Cp*Mo(CO)3Me], 1 with various chalcogenide ligands such as Li[BH2E3] and Li[BH3EFc] (E = S, Se or Te; Fc = (C5H5-Fe-C5H4)) has been described. Room temperature reaction of 1 with Li[BH2E3] (E = S and Se) yielded metal chalcogenide complexes [Cp*Mo(CO)2(η2-S2CCH3)], 2 and [Cp*Mo(CO)2(η1-SeC2H5)], 3. In compound 2, {Cp*Mo(CO)2} fragment adopts a four-legged piano-stool geometry with a η2-dithioacetate moiety. In contrast, treatment of 1 with Li[BH3(EFc)] (E = S, Se or Te; Fc = C5H5-Fe-C5H4) yielded borate complexes [Cp*Mo(CO)2(μ-H)(μ-EFc)BH2], 4-6 in moderate yields. Compounds 4-6 are too unstable and gradual conversion to [{Cp*Mo(CO)2}2(μ-H)(μ-EFc] (7: E = S; 8: Se) and [{Cp*Mo(CO)2}2(μ-TeFc)2], 9 happened by subsequent release of BH3. All the compounds have been characterized by mass spectrometry, IR, multinuclear NMR spectroscopy and structures were unequivocally established by crystallographic analysis for compounds 2, 3 and 7. © Indian Academy of Sciences.

Journal of Chemical Sciences

Reactivity of [Cp*Mo(CO)3Me] with chalcogenated borohydrides Li[BH2E3] and Li[BH3EFc] (Cp* = (η5-C5Me5); E = S, Se or Te; Fc = (C5H5-Fe-C5H4))

Reaction of [1,2-(Cp*RuH)2B3H 7](1;Cp* = η-C5Me5) with [Mo(CO) 3(CH3CN)3] yielded arachno-[(Cp*RuCO) 2B2H6](2), which exhibits a butterfly structure, reminiscent of 7 sep B4H10. Compound 2 was found to be a very good precursor for the generation of bridged borylene species. Mild pyrolysis of 2 with [Fe2(CO)9] yielded a triply bridged heterotrinuclear borylene complex [(μ3-BH) (Cp*RuCO)2(μ-CO){Fe(CO)3}] (3) and bis-borylene complexes [{(μ3-BH)-(Cp*Ru)(μ-CO)}2Fe 2(CO)5](4) and [{(μ3-BH)(Cp*Ru)Fe(CO) 3}2(μ-CO)] (5). In a similar fashion, pyrolysis of 2 with [Mn2(CO)10] permits the isolation of μ3-borylene complex [(μ3-BH)-(Cp*RuCO) 2(μ-H)(μ-CO){Mn(CO)3}] (6) . Both compounds 3 and 6 have a trigonal-pyramidal geometry with the μ3-BH ligand occupying the apical vertex, whereas 4 and 5 can be viewed as bicapped tetrahedra, with two μ3-borylene ligands occupying the capping position. The synthesis of tantalum borylene complex [(μ3-BH)(Cp*TaCO) 2(μ-CO){Fe(CO)3}] (7) was achieved by the reaction of [(Cp*Ta)2B4H8(μ-BH4)] at ambient temperature with [Fe2(CO)9]. Compounds 2-7 have been isolated in modest yield as yellow to red crystalline solids. All the new compounds have been characterized in solution by mass spectrometry; IR spectroscopy; and 1H, 11B, and 13C NMR spectroscopy and the structural types were unequivocally established by crystallographic analysis of 2-6. © 2010 Wiley-VCH Verlag GmbH &amp; Co. KGaA.

Chemistry - A European Journal

From metallaborane to borylene complexes: Syntheses and structures of triply bridged ruthenium and tantalum borylene complexes

Reaction of [(η5-C5Me5)MCl4], 1-2 (1: M = Mo and 2: W) with six fold excess of [LiBH4·thf] followed by thermolysis with excess chalcogen powders (S, Se and Te) yielded dichalcomolybda- and tungstaboranes, [(η5-C5Me5M)2B4H4E2], 5-8 (5: M = Mo, E = S; 6: M = Mo, E = Se; 7: M = Mo, E = Te; 8: M = W, E = Se) in modest yields. The geometry of 5-8 resembles a hexagonal bipyramid with a missing connectivity of two chalcogen vertices and a very short cross cage metal-metal bonding. All these new dichalcometallaboranes have been characterized by mass, 1H, 11B, 13C NMR spectroscopy, and the structural types were unequivocally established by crystallographic analysis of compound 6. © 2009 Elsevier B.V. All rights reserved.

Direct insertion of sulfur, selenium and tellurium atoms into metallaborane cages using chalcogen powders

The reaction of the [(η5-C5Me5) MoCl4] complex with [LiBH4·THF] in toluene at -70 °C, followed by pyrolysis at 110 °C, afforded dark brown [(η5-C5Me5Mo)3MoB 9H18], 2, in parallel with the known [(η5- C5Me5Mo)2B5H9], 1. Compound 2 has been characterized in solution by 1H, 11B, and 10C NMR spectroscopy and elemental analysis, and the structural types were unequivocally established by crystallographic studies. The title compound represents a novel class of vertex-fused clusters in which a Mo atom has been fused in a perpendicular fashion between two molybdaborane clusters. Electronic structure calculations employing density functional theory yield geometries in agreement with the structure determinations, and on grounds of density functional theory calculations, we have analyzed the bonding patterns in the structure . © 2010 American Chemical Society.

Inorganic Chemistry

Vertex-fused metallaborane clusters: Synthesis, characterization and electronic structure of [(η5-C5Me5Mo) 3MoB9H18]

Reaction of [Cp*TaCl4] (Cp* = η5- C5Me5) with a sixfold excess of LiBH4· thf followed by BH3·thf in toluene at 100°C led to the isolation of hydrogen-rich metallaboranes [(Cp*Ta)2B 4H10] (1), [(Cp*Ta)2B5H 11] (2), [(Cp*Ta)2B5H10) (C6H4CH3)] (3), and [(Cp*TaCl) 2B5H11] (4) in modest yield. Compounds 1-3 are air- and moisture-sensitive but 4 is reasonably stable in air. Their structures are predicted by the electron-counting rules to be a bicapped tetrahedron (1), bicapped trigonal bipyramids (2, 3), and a nido structure based on a closo dodecahedron (4). Yellow tantalaborane 1 has a nido geometry with C2v symmetry and is isostructural with [(Cp*M)2B4H 8] (M = Cr and Re); whereas 2 and 3 are C3v-symmetric and isostructural with [(Cp*M)2B5H9] (M = Cr, Mo, W) and [(Cp*ReH)2B5Cl5]. The most remarkable feature of 4 is the presence of a hydride ligand bridging the ditantalum center to form a symmetrical tantalaborane cluster with a long Ta-Ta bond (3.22 Å). Cluster 4 is a rare example of electronically unsaturated metallaborane containing four TaHB bonds. All these new metallaboranes have been characterized by mass spectrometry, 1H, 11B, and 13C NMR spectroscopy, and elemental analysis, and the structural types were unequivocally established by crystallographic analysis of 1-4. © 2008 Wiley-VCH Verlag GmbH &amp; Co. KGaA.

Metallaboranes of the early transition metals: Direct synthesis and characterization of [{(η5-C5Me5)Ta} 2BnHm] (n=4, m = 10; n = 5, m = 11), [{(η5-C5Me5)Ta}2B 5H10(C6H4CH3)]

Journal	Angewandte Chemie - International Edition
ISSN	14337851
Open Access	No