title: First-row transition-metal-diborane and -borylene complexes.
abstract: 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)4 Mn}(η(6) -B2 H6 ){Mn(CO)3 }2 (μ-H)] (1) and a triply bridged borylene complex [(μ3 -BH)(Cp*Co)2 (μ-CO)(μ-H)2 MnH(CO)3 ] (2). In a similar fashion, [Re2 (CO)10 ] generated [(μ3 -BH)(Cp*Co)2 (μ-CO)(μ-H)2 ReH(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)3 Ru3 (CO)9 B] (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 (1) H, (11) B, (13) C 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.
authors.affiliation: Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036 (India), Fax: (+91) 44 2257 4202.
authors.forename: Dudekula
authors.initials: D
authors.lastname: Sharmila
authors.forename: Bijan
authors.initials: B
authors.lastname: Mondal
authors.forename: Rongala
authors.initials: R
authors.lastname: Ramalakshmi
authors.forename: Sangita
authors.initials: S
authors.lastname: Kundu
authors.forename: Babu
authors.initials: B
authors.lastname: Varghese
authors.forename: Sundargopal
authors.initials: S
authors.lastname: Ghosh
keywords: X-ray diffraction; boranes; cobalt; density functional calculations; manganese