No abstract

Erfolgreiche Borversuche: Mit [μ‐BtBu{(η5‐C5H5)Mn(CO)2}2] wurde der erste Alkylborylenkomplex röntgenkristallographisch charakterisiert. Sein substituiertes Gegenstück [μ‐BtBu{(η5‐C5H4Me)Mn(CO)2}2] reagiert glatt mit [Pd(PCy3)2] (Cy=Cyclohexyl) unter Bildung des ersten heterometallischen μ3‐Borylenkomplexes 1 (siehe Bild; rot O, gelb P, schwarz C). DFT‐ und ELF‐Rechnungen belegen eine lokalisierte Bindungssituation für 1.

In 1995 we reported on the first spectroscopically characterized borylene complexes [m-BX{(h 5 -C 5 H 4 R)Mn(CO) 2 } 2 ] (1: X = NMe 2 , R = H; 2: X = tBu, R = Me) [1] and the molecular structure of 1. During the past decade, intense research efforts were focused on borylene complexes, [2] and many different coordination modes for ligands of the type BÀR were described and include terminal, [3] hetero-dinuclear, [4] and semibridging [5] species, thus experimentally proving the predicted close relationship between borylene ligands and CO. [6,7] More recent studies focused on the reactivity of borylene complexes and revealed some interesting characteristics of these species, for example, i) the potential of terminal borylene ligands to be transferred to metallic [8] and nonmetallic [9] substrates, ii) the strong tendency of some terminal borylene ligands to add metal bases of the type [M(PR 3 ) n ] (M = Pd, Pt), [5,10] and iii) the exceptional stability of the central Mn 2 B framework in 1.[7] This stability allowed for elusive substitution reactions at the borylene center without cleavage of the metal-boron framework.[11] Given the pronounced thermodynamic stability of these compounds with respect to M-B dissociation, [6,7] the latter finding may appear surprising; DFT calculations revealed a build-up of positive charge at the boron center, and hence, the M-B bond is kinetically labile and susceptible to nucleophilic cleavage.