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.

Sundargopal Ghosh

Department Of Chemistry

Chalcogen atoms

Chalcogens

CRYSTALLOGRAPHIC ANALYSIS

Metal-metal bonding

NMR spectroscopy

STRUCTURAL TYPE

boron

Boron Compounds

Molybdenum

Nuclear magnetic resonance spectroscopy

Powder metals

selenium

Sulfur

Tellurium

Tellurium compounds

Atoms

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 Organometallic Chemistry

Reaction of {η5 -C5Me5)MoCl 4 with a 10-fold excess of LiBH4 followed by thermolysis with excess BH3·THF in toluene led to the formation of two oxamolybdaborane clusters, (η5-C5Me 5Mo)2B5(μ3OEt)H6R (2, R = H; 3, R = n-BuO). Clusters 2 and 3 have been characterized by 1H, 11B, and 13C NMR spectra and X-ray crystal structure determinations. 2 and 3 are notable examples of oxametallaborane compounds where oxygen is contiguously bound to both the cluster metal (molybdenum) and the boron atom. © 2009 American Chemical Society..

Organometallics

Unusual open eight-vertex oxamolybdaboranes: Structural characterizations of (η5-C5Me5Mo)2B 5(μ-OEt)H6R (R = H and n-BuO)

Reaction of (η5-C5Me5)MoCl4 with 6-fold excess of LiBH4·thf followed by pyrolysis with BHCl2·SMe2 in toluene at 90 °C yielded known (η5-C5Me5Mo)2B5H9 (1) and B-Cl inserted (η5-C5Me5Mo)2B5H8Cl (2), (η5-C5Me5Mo)2B5H7Cl2 (3-5, three isomers) and (η5-C5Me5Mo)2B5H5Cl4 (6). In addition, reaction of (η5-C5Me5Mo)2B5H9 with 5-fold excess of n-BuLi followed by excess of MeI in THF yielded B-Me inserted metallaboranes (η5-C5Me5Mo)2B5H7(CH3)2 (7, 8 two isomers) and (η5-C5Me5Mo)2B5H6(CH3)3 (9, 10 two isomers). Isolated yields of 2-6 are poor but 7-10 are modest to good. Compounds 2-10 can be viewed as bicapped closo trigonal bipyramidal geometry. All the new compounds have been characterized in solution by IR, 1H, 11B, 13C NMR and mass spectroscopy as simple substitution derivatives of (η5-C5Me5Mo)2B5H9 and the structural types were unequivocally established by crystallographic analysis of compounds 2, 3, 5 and 6. © 2008 Elsevier B.V. All rights reserved.

Substitution at boron in molybdaborane frameworks: Synthesis and characterization of isomeric (η5-C5Me5Mo)2B5HnXm (when X = Cl: n = 5, 7, 8; m = 4, 2, 1 and X = Me: n = 6, 7; m = 3, 2)

In addition to (η 5-C 5Me 5W) 25H 9, (η 5-C 5Me 5W) 3(μ-H)B 8H 8, and (η 5-C 5Me 5W) 2B 7H 9 reported earlier, thermolysis of {η 5-C 5Me 5 W}H 3B 4H 8 (1) with BH 3·THF leads to the formation of bicapped closo-{η 5C 5Me 5W} 2B 6H 10 (2) in parallel with a B-B linked djmer of {η 5-C 5Me 5W} 2B 5H 9 (4) and bis-{η 5-C 5Me 5W) 2B 5H 8} 2 (3). Reaction of 4 with a 3-fold excess of Fe 2(CO) 9 in hexane generates an iron analogue of 2, (η 5-C 5Me 5W) 2B 5H 9Fe(CO) 3 (5) in-46% yield. AU the metallaboranes, 2, 3, and 5, have been characterized by 1H, 11B NMR spectra and crystal structure determinations. The structures of 2 and 5 appear to follow the regular electron counting rules as they possess seven skeletal electron pairs (sep) appropriate for bicapped octahedral structures. However, their electronic structures revealed by a molecular orbital analysis is more closely related to that of [{η 5-C 5Me 5Re} 2B 7H 7], a cluster that does not obey the classical electron counting rules. Clusters 2 and 5 are notable examples of closo clusters containing four bridging hydrogens. 3 is a coupled-cage structure in which two bicapped trigonal bipyramidal frameworks, W 2B 5, are joined by an exopolyhedral boron-boron bond. © 2007 American Chemical Society.

Linked and fused tungstaborane clusters: Synthesis, characterization, and electronic structures of bis(η 5C 5Me 55W) 2B 5H 8} 2 and (η 5-C 5Me 55W) 2{Fe(CO) 3} n,B 6-nH 10-n, n = 0, 1

European Journal of Inorganic Chemistry

Novel 1,2-Dicarba-closo-dodecaborane(12) Derivatives of Selenium

Journal of the American Chemical Society

Synthesis and Characterization of the Octahydrotriborate Complexes Cp*V(B3H8)2and Cp*Cr(B3H8)2and the Unusual Cobaltaborane Cluster Cp*2Co2(B6H14)

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

Journal	Journal of Organometallic Chemistry
ISSN	0022328X
Open Access	No