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152. Synthesis and characterization of hypoelectronic rhenaboranes. Analysis of the geometric and electronic structures of species following neither borane nor metal cluster electron-counting paradigms

Author

Guennic, Boris Le, Jiao, Haijun, Kahlal, Samia, Saillard, Jean-Yves, Halet, Jean-Francois, Ghosh, Sundargopal, Maoyu Shang, Beatty, Alicia M., Rheingold, Arnold L., and Fehlner, Thomas P.

Subjects
Rhenium -- Electric properties, Borane -- Electric properties, Chemical synthesis -- Research, Chemistry
Abstract

The synthesis of the characterization of a series of dirhenium metallaboranes containing 5-10m boron atoms is described. Competition between main group and transition metal electronic properties is also presented.

Published
2004

153. Cooperative B–H activation by Cp* based κ2-N,S-chelated Ru(II) and Mo(II) complexes (Cp* = η5-C5Me5).

Author

Saha, Suvam, Haridas, Anagha, Assanar, Faneesha, Bansal, Charu, Sudhadevi Antharjanam, P. K., and Ghosh, Sundargopal

Subjects
MOLYBDENUM, HIGH temperatures, BORANES, RUTHENIUM compounds, BORATES
Abstract

The chemistry of the Cp* based κ2-N,S-chelated ruthenium complex, [Cp*RuPPh3(κ2-N,S-(NC7H4S2)], 1 with different boranes has been explored. The room temperature reaction of 1 with BH3·THF and bulky boranes, such as MesBH2 and H2BArF, led to the formation of different dihydridoborate complexes, [{κ3-S,H,H-(NBH2R)(S2H4C7)}RuCp*], 2–4 (2: R = H, 3: R = Mes, and 4: R = ArF; Mes = 2,4,6-trimethylphenyl, and ArF = 3,5-bistrifluoromethyl-benzene). In contrast, the Cp* based κ2-N,S-chelated molybdenum complex, [Cp*Mo(CO)2{κ2-N,S-(NC7H4S2)}], 5, yielded the agostic borate species, [Cp*Mo(CO)2{κ2-S,H-(NBH2R) (NC7H4S2)}], 6 and 7 (6: R = Mes and 7: R = ArF) at elevated temperatures. [ABSTRACT FROM AUTHOR]

Published
2022
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161. Role of the transition metal in metallaborane chemistry. Reactivity of (Cp(super *)ReH2)2B4H4 with BH3.thf, CO and Co2(CO)8

Author

Ghosh, Sundargopal, Xinjian Lei, Maoyu Shang, and Fehlner, Thomas P.

Subjects
Rhenium -- Chemical properties, Borane -- Chemical properties, Chemistry
Abstract

The formation of (Cp(super *)ReH2)2B4H4(2) from Cp(super *)ReCl4 and its reaction with BH3.thf, CO and Co2(CO)8 are described. The characterizations of intermediates reveal mechanistic details.

Published
2000

167. Metal‐Stabilized [B8H8]2− Derivatives with Dodecahedral Structure in the Solid and Solution States: [(Cp2MBH3)2B8H6] (Cp=η5‐C5H5; M=Zr (1‐Zr) and Hf (1‐Hf))

Author

Kar, Sourav, Bairagi, Subhash, Joshi, Gaurav, Jemmis, Eluvathingal D., and Ghosh, Sundargopal

Subjects
SOLID solutions, STRUCTURAL stability, DIANIONS, POLYHEDRA, METALS
Abstract

Despite the synthesis and structural characterization of closo‐hydroborate dianions, [BnHn]2− (n=6–12) more than 50 years ago, some ambiguity remains about the structure of [B8H8]2−. Although the solid‐state structure of [B8H8]2− was established by single‐crystal X‐ray studies in 1969, fast rearrangements in solution at accessible temperatures prevented its detailed characterization. We therefore stabilized a derivative of [B8H8]2− by using Cp2MBH3 and structurally characterized two new octaborane analogues, [(Cp2MBH3)2B8H6] (Cp=η5‐C5H5; M=Zr (1‐Zr) and Hf (1‐Hf)), so that the dynamics of the B8 skeleton were arrested. The solid‐state structures of both 1‐Zr and 1‐Hf comprise a dodecahedron core protected by {Cp2MBH3} moieties on both sides of the cluster. Spectroscopic characterization (11B NMR) validates the intactness of the B8 dodecahedron core in solution as well. Theoretical calculations establish that the two exo‐{Cp2MBH3} fragments provide structural and electronic structural stability to the B8 core and its intact dodecahedral dianionic nature. Furthermore, we propose isodesmic equations for the formation of higher analogues of the Bn core (n>8) guarded by different group 4 transition metals. Our analysis suggests that, as we move to higher polyhedra (n>10), the formation becomes unfavourable irrespective of metal. [ABSTRACT FROM AUTHOR]

Published
2021
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168. Synthesis, Structural Characterization, and Theoretical Studies of Silver(I) Complexes of Dihydrobis(2-mercapto-benzothiazolyl) Borate

Author

Gomosta, Suman, Ramalakshmi, Rongala, Arivazhagan, Chinnappa, Haridas, Anagha, Raghavendra, Beesam, Maheswari, Kuppaiyandi, Roisnel, Thierry, Ghosh, Sundargopal, Indian Institute of Technology Madras (IIT Madras), Institut des Sciences Chimiques de Rennes (ISCR), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA), Council of Scientific and Industrial Research, CSIR, New Delhi, India [01(2837)/15/EMR-II], IIT Madras, UGC, CSIR, Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Silver, Scorpionate, Borates, [CHIM]Chemical Sciences, ComputingMilieux_MISCELLANEOUS, Amidine, Phosphine
Abstract

International audience

Published
2019

178. A covalently linked dimer of [Ag25(DMBT)18]−

Author

Bodiuzzaman, Mohammad, primary, Nag, Abhijit, additional, Pradeep Narayanan, Raghu, additional, Chakraborty, Ankush, additional, Bag, Ranjit, additional, Paramasivam, Ganesan, additional, Natarajan, Ganapati, additional, Sekar, Govindasamy, additional, Ghosh, Sundargopal, additional, and Pradeep, Thalappil, additional

Published
2019
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185. Chalcogen Stabilized bis‐Hydridoborate Complexes of Cobalt: Analogues of Tetracyclo[4.3.0.02,4.03,5]nonane.

Author

Joseph, Benson, Gomosta, Suman, Prakash, Rini, Roisnel, Thierry, Phukan, Ashwini K., and Ghosh, Sundargopal

Subjects
CONDUCTION electrons, BORON, CHEMICAL yield, ATOMS in molecules theory, CYCLOPENTANE
Abstract

Treatment of Li[BH3ER] (E=Se or Te, R=Ph; E=S, R=CH2Ph) with [Cp*CoCl]2 led to the formation of hydridoborate complexes, [{CoCp*Ph}{Cp*Co}{μ‐EPh}{μ‐κ2‐E,H‐EBH3}], 1a and 1 b (1 a: E=Se; 1 b: E=Te) and a bis‐hydridoborate species [Cp*Co{μ‐κ2‐Se,H‐SeBH3}]2, 2. All the complexes, 1 a, 1 b and 2 are stabilized by β‐agostic type interaction in which 1 b represents a novel bimetallic borate complex with a rare B−Te bond. QTAIM analysis furnished direct proof for the existence of a shared and dative B‐chalcogen and Co‐chalcogen interactions, respectively. In parallel to the formation of the hydridoborate complexes, the reactions also yielded tetracyclic species, [Cp*Co{κ3‐E,H,H‐E(BH2)2‐C5Me5H3}], 3 a and 3 b (3 a: E=Se and 3 b: E=S), wherein the bridgehead boron atoms are surrounded by one chalcogen, one cobalt and two carbon atoms of a cyclopentane ring. Molecules 3 a and 3 b are best described as the structural mimic of tetracyclo[4.3.0.02,4.03,5]nonane having identical structure and similar valence electron counts. [ABSTRACT FROM AUTHOR]

Published
2020
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189. Small Ring Molecules Comprising 3–6 Boron Atoms: An Account on Synthesis, Structure, and Orbital Engineering

Author

Kar, Sourav, Bairagi, Subhash, Joshi, Gaurav, Jemmis, Eluvathingal D., Himmel, Hans-Jörg, and Ghosh, Sundargopal

Abstract

Unlike carbon, boron does not usually form ring compounds due to its electron-deficiency-driven affinity toward polyhedral geometries. The polyhedral boranes having closo-, nido-, arachno-, or hypho-shapes can be structurally and electronically correlated using various electron counting rules developed by Wade, Mingos, and one of us. However, in the last few decades, boron chemistry progressed significantly toward ring systems. In this regard, three of our research groups have made significant contributions to the development of boron ring molecules through different synthetic approaches. While the Ghosh group generally starts from transition metal (TM) stabilized boron species, the Himmel group typically starts from electron-deficient TM-free boron ring compounds. On the other hand, the Jemmis group studies boron rings and their analogous structures computationally and develops electron counting rules to describe them. Over the past few years, through different synthetic approaches, several boron ring molecules have been prepared by our research groups and others. Recently, the Ghosh group has reported the synthesis of an almost planar B6-ring that is stabilized by a TM template. Similarly, the B3-, B4-, and B5-rings have also been stabilized in the coordination spheres of early and late TMs. The recent work of Himmel has uncovered some remarkable diversity in the structures and bonding of B3and B4rings, along with their redox reactions. The well-known hydrocarbon analogues of these borane rings, i.e., two-dimensional aromatic compounds [C3H3]+, [C5H5]−, [C6H6], etc., are governed by Hückel’s (4n+ 2) π-electron rule. However, planar or nearly planar borane rings are not seriously thought of as achievable targets. One of the reasons for this is the influence of the Rudolph diagram in the thought process of chemists that the nido- and arachno-structures generated from closo-polyhedral boranes must also be three-dimensional (3D) fragments. However, this is not the only possibility. Flat arachno- and nido-boranes reminiscent of their organic counterparts follow from an equivalent of the Rudolph diagram. Therefore, this Account is very much necessary for the boron community, in particular, to design and synthesize 3–6 membered boron rings or beyond. This Account aims to highlight significant ongoing experimental and theoretical results in this area from our groups, in addition to relevant works from other groups wherever appropriate. This will also bring into focus various ways in which the flat Bn-systems can be stabilized, such as the utilization of TM or main group caps, utilization of various Lewis bases, edge-condensation of small rings, control over the electron count, and orbital engineering.

Published
2024
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190. Cluster Fusion: Face-Fused Macropolyhedral Tetracobaltaboranes

Author

Zafar, Mohammad, Kar, Sourav, Nandi, Chandan, Ramalakshmi, Rongala, and Ghosh, Sundargopal

Abstract

In an effort to isolate the 16-vertex supraicosahedral cobaltaborane [(Cp*Co)3B12H12Co{Cp*CoB4H9}] (Cp* = η5-C5Me5), we have pyrolyzed an in situ generated intermediate, obtained from the fast metathesis of [Cp*CoCl]2and [LiBH4·THF], with an excess amount of [BH3·THF]. Although the objective of isolating the 16-vertex cobalt analogue was not achieved, the reaction yielded a closo-19-vertex face-fused cluster presenting icosahedral {Co3B9}, tetrahedral {B4}, and 10-vertex {CoB9} units. The reaction also yielded a 20-vertex face-fused cluster that contains icosahedral {Co4B8}, square-pyramidal {CoB4}, tetrahedral {Co2B2}, and nido-{CoB7} units.

Published
2024
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191. Synthesis, Structure, and Bonding of Group 8 Transition Metal Germyl Complexes, [Cp*M{κ2-Ge,S-GeCl2C7H4NS2}(PPh3)] (M = Ru or Os)

Author

Saha, Suvam, Assanar, Faneesha, Ahmad, Asif, Bains, Ajay, Nagendran, Selvarajan, and Ghosh, Sundargopal

Abstract

The hemilabilty of 1,3-S,N-chelated transition metal (TM) complexes [Cp*M{κ2-S,N-C7H4NS2}(PPh3)] (Cp* = η5-C5Me5) (1a: M = Ru and 1b: M = Os) allows them to capture GeCl2to generate TM–germyl complexes [Cp*M{κ2-Ge,S-GeCl2C7H4NS2}(PPh3)] (2a: M = Ru and 2b: M = Os). Based on the structural parameters, these complexes can be described as tethered germyl complexes. To investigate the bonding modes of these complexes, density functional theory (DFT) computations were carried out.

Published
2024
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192. Unusual Organic Chemistry of a Metallaborane Substrate: Formation of a Tantalaborane Complex with a Bridging Acyl Group (μ-η2)

Author

Bose, Shubhankar Kumar, Geetharani, K., Varghese, Babu, and Ghosh, Sundargopal

Abstract

The addition of LiBH4·THF to Cp*TaCl4(1; Cp* = η5-C5Me5) at −40 °C, followed by mild pyrolysis with excess BH3·THF, results in the formation of the μ-acyl complex (Cp*Ta)2B4H8(μ-η2-COCH3) (2). The title compound represents a novel class of μ-acyl complexes in which the bicapped-tetrahedral unit (Cp*Ta)2B4H8is bridged by a μ-η2-COCH3acyl ligand.

Published
2024
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193. Heterometallic Triply-Bridging Bis-Borylene Complexes.

Author

Bag, Ranjit, Kar, Sourav, Saha, Suvam, Gomosta, Suman, Raghavendra, Beesam, Roisnel, Thierry, and Ghosh, Sundargopal

Subjects
MASS spectrometry, NUCLEAR magnetic resonance spectroscopy, TRANSITION metals, FRONTIER orbitals, BAND gaps, CHEMICAL bonds
Abstract

Triply-bridging bis-{hydrido(borylene)} and bis-borylene species of groups 6, 8 and 9 transition metals are reported. Mild thermolysis of [Fe2(CO)9] with an in situ produced intermediate, generated from the low-temperature reaction of [Cp*WCl4] (Cp*=η5 -C5Me5) and [LiBH4·THF] afforded triply-bridging bis-{hydrido(borylene)}, [(μ3- BH)2H2{Cp*W(CO)2}2{Fe(CO)2}] (1) and bis-borylene, [(μ3- BH)2{Cp*W(CO)2}2{Fe(CO)3}] (2). The chemical bonding analyses of 1 show that the B H interactions in bis-{hydrido (borylene)} species is stronger as compared to the M H ones. Frontier molecular orbital analysis shows a significantly larger energy gap between the HOMO-LUMO for 2 as compared to 1. In an attempt to synthesize the ruthenium analogue of 1, a similar reaction has been performed with [Ru3(CO)12]. Although we failed to get the bis-{hydrido(borylene)} species, the reaction afforded triply-bridging bis-borylene species [(μ3- BH)2{WCp*(CO)2}2{Ru(CO)3}] (2’), an analogue of 2. In search for the isolation of bridging bis-borylene species of Rh, we have treated [Co2(CO)8] with nido-[(RhCp*)2(B3H7)], which afforded triply-bridging bis-borylene species [(μ3- BH)2(RhCp*)2Co2(CO)4(μ-CO)] (3). All the compounds have been characterized by means of single-crystal X-ray diffraction study; ¹ H, 11B, 13C NMR spectroscopy; IR spectroscopy and mass spectromet [ABSTRACT FROM AUTHOR]

Published
2020
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194. Stabilization of Classical [B2H5]−: Structure and Bonding of [(Cp*Ta)2(B2H5)(μ‐H)L2] (Cp*=η5‐C5Me5; L=SCH2S)

Author

Saha, Koushik, Ghorai, Sagar, Kar, Sourav, Saha, Suvam, Halder, Rajarshi, Raghavendra, Beesam, Jemmis, Eluvathingal D., and Ghosh, Sundargopal

Subjects
TANTALUM, METAL carbonyls, CHEMICAL adducts
Abstract

The room‐temperature reaction of [Cp*TaCl4] with LiBH4⋅THF followed by addition of S2CPPh3 results in pentahydridodiborate species [(Cp*Ta)2(μ,η2:η2‐B2H5)(μ‐H)(κ2,μ‐S2CH2)2] (1), a classical [B2H5]− ion stabilized by the binuclear tantalum template. Theoretical studies and bonding analysis established that the unusual stability of [B2H5]− in 1 is mainly due to the stabilization of sp2‐B center by electron donation from tantalum. Reactions to replace the hydrogens attached to the diborane moiety in 1 with a 2 e {M(CO)4} fragment (M=Mo or W) resulted in simple adducts, [{(Cp*Ta)(CH2S2)}2(B2H5)(H){M(CO)3}] (6: M=Mo and 7: M=W), that retained the diborane(5) unit. [ABSTRACT FROM AUTHOR]

Published
2019
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