Diborane(4) and diborane(6) molecules are demanding renewed interest due to their varied reactivity towards diverse substrates. The chemistry of molecules comprising electron-precise B-B bonds has witnessed swift developments in the recent years. In spite of the continuous interest and extensive efforts in the synthesis of diborane compounds, the formation of boron-boron bonds is still difficult and uncontrolled. On the other hand, the diborene molecules (R-B[dbnd]B-R′; R, R′ = H, phosphine, amine, NHC etc), are also of significant interest owing to their ability to regulate the property of biradicals by changing the substituents of the parent diborene(2), HB[dbnd]BH. In addition, transition metal diborene species exhibit fascinating photo-physical properties. In this review, we have delivered a background of B-B bond formation and a synopsis of the latest developments in the synthesis of boron-boron single and multiple bonds. The reactivity of diborane/diborene complexes towards various transition metals has also been discussed in detail. © 2019 Elsevier B.V.

Sundargopal Ghosh

Department Of Chemistry

Rosmita Borthakur

Koushik Saha

Sourav Kar

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

Coordination Chemistry Reviews

The reaction of [(Cp*Mo)2(μ-Cl)2B2H6] (1) with CO at room temperature led to the formation of the highly fluxional species [{Cp*Mo(CO)2}2{μ-η2:η2-B2H4}] (2). Compound 2, to the best of our knowledge, is the first example of a bimetallic diborane(4) conforming to a singly bridged Cs structure. Theoretical studies show that 2 mimics the Cotton dimolybdenum–alkyne complex [{CpMo(CO)2}2C2H2]. In an attempt to replace two hydrogen atoms of diborane(4) in 2 with a 2e [W(CO)4] fragment, [{Cp*Mo(CO)2}2 B2H2W(CO)4] (3) was isolated upon treatment with [W(CO)5⋅thf]. Compound 3 shows the intriguing presence of [B2H2] with a short B−B length of 1.624(4) Å. We isolated the tungsten analogues of 3, [{Cp*W(CO)2}2B2H2W(CO)4] (4) and [{Cp*W(CO)2}2B2H2Mo(CO)4] (5), which provided direct proof of the existence of the tungsten analogue of 2. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Angewandte Chemie - International Edition

Synthesis, Structure, Bonding, and Reactivity of Metal Complexes Comprising Diborane(4) and Diborene(2): [{Cp*Mo(CO)2}2{μ-η2:η2-B2H4}] and [{Cp*M(CO)2}2B2H2M(CO)4], M=Mo,W

A combined experimental and quantum chemical study of Group 7 borane, trimetallic triply bridged borylene and boride complexes has been undertaken. Treatment of [{Cp∗CoCl}2] (Cp∗=1,2,3,4,5-pentamethylcyclopentadienyl) with LiBH4·thf at -78°C, followed by room-temperature reaction with three equivalents of [Mn2(CO)10] yielded a manganese hexahydridodiborate compound [{(OC)4Mn}(η6-B2H6){Mn(CO)3}2(μ-H)] (1) and a triply bridged borylene complex [(μ3-BH)(Cp∗Co)2(μ-CO)(μ-H)2MnH(CO)3] (2). In a similar fashion, [Re2(CO)10] generated [(μ3-BH)(Cp∗Co)2(μ-CO)(μ-H)2ReH(CO)3] (3) and [(μ3-BH)(Cp∗Co)2(μ-CO)2(μ-H)Co(CO)3] (4) in modest yields. In contrast, [Ru3(CO)12] under similar reaction conditions yielded a heterometallic semi-interstitial boride cluster [(Cp∗Co)(μ-H)3Ru3(CO)9B] (5). The solid-state X-ray structure of compound 1 shows a significantly shorter boron-boron bond length. The detailed spectroscopic data of 1 and the unusual structural and bonding features have been described. All the complexes have been characterized by using 1H, 11B, 13C NMR spectroscopy, mass spectrometry, and X-ray diffraction analysis. The DFT computations were used to shed light on the bonding and electronic structures of these new compounds. The study reveals a dominant B-H-Mn, a weak B-B-Mn interaction, and an enhanced B-B bonding in 1. © 2015 Wiley-VCH Verlag GmbH & Co. KGaA.

Chemistry - A European Journal

First-Row Transition-Metal-Diborane and -Borylene Complexes

A series of novel Cp*-based (Cp*=η5-C 5Me5) agostic, bis(σ-borate), and boratrane complexes have been synthesized from diruthenium and dirhodium analogues of pentaborane(9). The synthesis and structural characterization of the first neutral ruthenadiborane(6) analogue are also reported. This new route offers a very efficient method for the isolation of bis(σ-borate) and agostic complexes from diruthenapentaborane(9). © 2014 WILEY-VCH Verlag GmbH &amp; Co. KGaA, Weinheim.

Journal	Data powered by TypesetCoordination Chemistry Reviews
Publisher	Data powered by TypesetElsevier B.V.
ISSN	00108545
Open Access	No