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.

Sundargopal Ghosh

Department Of Chemistry

Rongala Ramalakshmi

Koushik Saha

Anamika Paul

Chalcogenides

lithium

Mass spectrometry

Molybdenum

Nuclear magnetic resonance spectroscopy

Organometallics

Sulfur

BORATE

BORATE COMPLEXES

CRYSTALLOGRAPHIC ANALYSIS

Ferrocenes

Metal chalcogenide

Multinuclear NMR spectroscopy

PIANO STOOL GEOMETRY

THIOACETATE

Iron compounds

Fulltext

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Journal of Chemical Sciences

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.

ACS Omega

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

In an effort to synthesize chalcogen-rich metallaheteroborane clusters of group 5 metals, thermolysis of [Cp∗TaCl4] (Cp∗ = n5-C5Me5) with thioborate ligand Li[BH2S3] was carried out, affording trimetallic clusters [(Cp∗Ta)3(μ-S)3(μ3-S)3B(R)], 1-3 (1, R = H; 2, R = SH; and 3, R = Cl). Clusters 1-3 are illustrative examples of cubane-type organotantalum sulfido clusters in which one of the vertices of the cubane is missing. In parallel to the formation of 1-3, the reaction also yielded tetrametallic sulfido cluster [(Cp∗Ta)4(μ-S)6(μ3-S)(μ4-O)], 6, having an adamantane core structure. Compound 6 is one of the rarest examples containing the μ4-oxo unit with a heavier early transition metal, i.e., tantalum. In an effort to isolate selenium analogues of clusters 1-3, we have isolated the trimetallic cluster [(Cp∗Ta)3(μ-Se)3(μ3-Se)3B(H)], 4, from the thermolytic reaction of [Cp∗TaCl4] and Li[BH2Se3]. In contrast, the thermolysis of [Cp∗TaCl4] with Li[BH2Te3] under the same reaction conditions yielded tantalum telluride complex [(Cp∗Ta)2(μ-Te)2], 5. Compounds 1-4 are hypo-electronic clusters with an electron count of 50 cluster valence electrons. All these compounds have been characterized by 1H, 11B{1H}, and 13C{1H} NMR spectroscopy; infrared spectroscopy; mass spectrometry; and single-crystal X-ray crystallography. The density functional theory calculations were also carried out to provide insight into the bonding and electronic structures of these molecules. Copyright © 2018 American Chemical Society.

Inorganic Chemistry

Trimetallic Cubane-Type Clusters: Transition-Metal Variation as a Probe of the Roots of Hypoelectronic Metallaheteroboranes

In an effort to synthesize trithiocarbonate complexes of molybdenum and ruthenium, we carried out the reaction of CS2 with the intermediates, obtained from the reaction of [Cp#ML3X], (1: Cp# = C5Me5, M = Mo, L1 = L2 = L3 = CO, X = Me; 2: Cp# = C5H5, M = Ru, L1 = L2 = PPh3, X = Cl and 3: Cp# = C5H5, M = Fe, L1 = L2 = CO, X = I) and [LiBH4⋅thf]. The reactions led to formation of the trithiocarbonate complexes [Cp*Mo(CO)2(μ-ɳ2:ɳ1-CS3)(CO)3MoCp*] (4) [Cp*Mo(CO)2(ɳ2-S2CSMe)] (5) and [Cp*Mo(CO)2(ɳ2-S2CMe)] (6) in moderate yields. Treatment of [CpRu(PPh3)2Cl] (2) with [LiBH4⋅thf] followed by mild pyrolysis of CS2 yielded the trithiocarbonate ruthenium complex [CpRuPPh3(ɳ2-S2CSMe)] (7). All the new compounds have been characterized by various spectroscopic techniques and the structures of compounds 4, 5 and 7 were unequivocally established by crystallographic analysis. © 2017

Journal of Organometallic Chemistry

Synthesis and structural characterization of trithiocarbonate complexes of molybdenum and ruthenium derived from CS2 ligand

The reaction of nido-[1,2-(Cp*RuH)2B3H 7] (1 a, Cp*=Î·5-C5Me 5) with [Mo(CO)3(CH3CN)3] under mild conditions yields the new metallaborane arachno-[(Cp*RuCO) 2B2H6] (2). Compound 2 catalyzes the cyclotrimerization of a variety of internal- and terminal alkynes to yield mixtures of 1,3,5- and 1,2,4-substituted benzenes. The reactivities of nido-1 a and arachno-2 with alkynes demonstrates that a change in geometry from nido to arachno drives a change in the reaction from alkyne-insertion to catalytic cyclotrimerization, respectively. Density functional calculations have been used to evaluate the reaction pathways of the cyclotrimerization of alkynes catalyzed by compound 2. The reaction involves the formation of a ruthenacyclic intermediate and the subsequent alkyne-insertion step is initiated by a [2+2] cycloaddition between this intermediate and an alkyne. The experimental and quantum-chemical results also show that the stability of the metallacyclic intermediate is strongly dependent on the nature of the substituents that are present on the alkyne. Everything changes but Ru: The reactivities of nido-[1,2-(Cp*RuH)2B3H7] and arachno-[(Cp*RuCO)2B2H6] with alkynes show that a change in geometry (nido to arachno) drives a change from alkyne-insertion to catalytic cyclotrimerization, respectively. Copyright © 2012 WILEY-VCH Verlag GmbH &amp; Co. KGaA, Weinheim.

Chemistry - A European Journal

A mechanistic study of the utilization of arachno-diruthenaborane [(Cp*RuCO)2B2H6] as an active alkyne-cyclotrimerization catalyst

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.

Angewandte Chemie - International Edition

A family of heterometallic cubane-type clusters with an exo-Fe(CO) 3 fragment anchored to the cubane

The reaction of [Cp*TaCl4], 1 (Cp* = η5-C5Me5), with [LiBH4· THF] at -78 °C, followed by thermolysis in the presence of excess [BH 3·THF], results in the formation of the oxatantalaborane cluster [(Cp*Ta)2B4H10O], 2 in moderate yield. Compound 2 is a notable example of an oxatantalaborane cluster where oxygen is contiguously bound to both the metal and boron. Upon availability of 2, a room temperature reaction was performed with [Fe2(CO) 9], which led to the isolation of [(Cp*Ta)2B 2H4O{H2Fe2(CO)6BH}], 3. Compound 3 is an unusual heterometallic boride cluster in which the [Ta 2Fe2] atoms define a butterfly framework with one boron atom lying in a semi-interstitial position. Likewise, the diselenamolybdaborane, [(Cp*Mo)2B4H4Se2], 4 was treated with an excess of [Fe2(CO)9] to afford the heterometallic boride cluster [(Cp*MoSe)2Fe6(CO) 13B2(BH)2], 5. The cluster core of 5 consists of a cubane [Mo2Se2Fe2B2] and a tricapped trigonal prism [Fe6B3] fused together with four atoms held in common between the two subclusters. In the tricapped trigonal prism subunit, one of the boron atoms is completely encapsulated and bonded to six iron and two boron atoms. Compounds 2, 3, and 5 have been characterized by mass spectrometry, IR, 1H, 11B, 13C NMR spectroscopy, and the geometric structures were unequivocally established by crystallographic analysis. The density functional theory calculations yielded geometries that are in close agreement with the observed structures. Furthermore, the calculated 11B NMR chemical shifts also support the structural characterization of the compounds. Natural bond order analysis and Wiberg bond indices are used to gain insight into the bonding patterns of the observed geometries of 2, 3, and 5. © 2011 American Chemical Society.

Synthesis, characterization, and electronic structure of new type of heterometallic boride clusters

Vanadaborane, [(CpV)2(B2H6)2] (Cp = η5-C5H5), 1 reacts with elemental sulfur to afford the hexasulflde cluster [(CpV)2S4(μ- η1-S2)], 2 In high yield. Compound 2 is a notable example of an organovanadium sulfide cluster In which the [V2S 4] atoms define a bicapped tetrahedron framework, with μ-η1-S2 ligand bridged the two (CpV) moieties. The sulfur atom In [V2S4] core in 2 Is a four-skeletal- electron donor isoelectronlc with the BH3 unit; therefore, the replacement of boron hydride in 1 by four sulfur atoms necessitates the formation of a bicapped tetrahedron [V2S4] framework. Furthermore, this Is the only reported example of a bimetallic hexasulflde cluster containing vanadium. Pyrolysls of 1 with bis-chalcogenide ligands such as Ph2S2 and Bz2Se2 (Bz = PhCH 2), results In the formation of substituted vanadahexaboranes [(CpV)2B4H12-xLx], 3-5 (3: L = SPh: x= 3; 4: L = SPh, x= 2; 5: L = SeBz: x= 1) in modest yield. All these new compounds have been characterized by mass, 1H, 11B, 13C NMR spectroscopy, and elemental analysis, and the structural types were unequivocally established by crystallographic analysis of compounds 2-5. © 2010 American Chemical Society.

Chemistry of vanadaboranes: Synthesis, structures, and characterization of organovanadium sulfide clusters with disulfido linkage

Reverse flow inside a parallel plate channel can be achieved by placing an obstruction at the entry. The present work is carried out to study the influence of (i) splitter plates behind the flat plate obstruction at the front end and (ii) splitter plates placed at the rear end of the channel in tandem with the obstruction at the front. The results show that the splitter plate at the front end has a slight unfavourable effect due to a little reduction in the reverse flow. However, when the splitter plate is placed at the rear end, it interferes with the alternate formation and shedding of vortices near the rear end. This interference depends upon the length of the splitter plate and also on its position relative to the exit of the test channel. The resulting flow field causes an increase in the magnitude of the reverse flow which remains constant over a wide range of splitter plate positions.

Journal	Data powered by TypesetJournal of Chemical Sciences
Publisher	Data powered by TypesetSpringer India
ISSN	09743626
Open Access	Yes