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Reaction of the bidentate Lewis acid 1,2-Fc(SnMe 2 Cl)(B(Me)Cl) ( 1 , Fc = 1,2-ferrocenylene) with 2-trimethylstannylpyridine gave a complex ( 2 ), in which the 2-pyridyl group forms a bridge between the Lewis acidic tin and boron centers. The structure of 2 was confirmed by multinuclear and two-dimensional NMR, single crystal X-ray diffraction, and elemental analysis. The crystal structure shows that the pyridyl moiety is positioned endo relative to the substituted Cp ring and UV–Vis spectroscopy revealed an enhancement of the ferrocene-centered dd transition in comparison to related complexes with pyridine as a terminal ligand.

A chiral 2-naphthylferrocenylcopper heteroaggregate (2) was prepared in high yield by reaction of (Sp-2-naphthylferrocenyl)trimethyltin with (C6F5Cu)4 and fully characterized by multinuclear NMR, single crystal X-ray diffraction, and elemental analysis. The reactivity of 2 toward boron halides was examined. Rearrangement reactions resulted in formation of 1,2-, 1,3-, and 1,1′-disubstituted naphthylferrocenylboranes.

The ferrocene-containing polymer [-fc-B(Br)-] n ( 6 ) with an average chain length of ca. 20 repeat units ( n = 20) is readily accessible from fc(BBr 2 ) 2 and HSiEt 3 [fc = (C 5 H 4 ) 2 Fe] via a novel polycondensation reaction. Treatment of 6 with excess THF yields the highly soluble alkoxy-substituted derivative [-fc-B(O(CH 2 ) 4 Br)-] n ( 10 ; n = 20).

The functionalization of polymeric materials with Lewis acidic boron sites has led to exciting new opportunities in diverse areas, ranging from new polymeric catalysts to the preparation of highly luminescent materials and the design of efficient sensor systems for nucleophiles. Recent advances in the preparation of these Lewis acidic boron polymers, their coordination behavior, and some of their intriguing applications are reviewed.

A comparative study on the reactivity and selectivity of arylcopper species in reactions with boron halides was performed. Mesitylcopper reacts with BX 3 (X=Cl, Br) in toluene at low temperature under highly selective formation of the monosubstituted boranes MesBX 2 . The dimesitylboranes Mes 2 BX are gradually formed with a twofold excess of the organocopper reagent at elevated temperature. In contrast, pentafluorophenylcopper shows a tendency for formation of B(C 6 F 5 ) 3 in reactions with BX 3 irrespective of the stoichiometry used, suggesting a strong impact of electronic factors on the selectivity of the aryl transfer reaction. New procedures for the synthesis of the pentafluorophenylboron halides C 6 F 5 BX 2 (X=Cl: 57%; X=Br: 62%) and of tris(pentafluorophenyl)borane (80%) and related mixed-substituted triarylboranes from the base-free isolable pentafluorophenylcopper precursor have been developed.

On the basis of intramolecular donor-acceptor pairing, a convenient way to realize important structural motifs in organometallic chemistry is presented. Ferrocene, bearing a (phosphino)boryl substituent (BRPPh2) at each of its cyclopentadienyl rings, was found to establish a novel type of ansa-structure through interannular head-to-tail bonding (1). This B2P2 bridge adopts an unusual non-planar conformation. For its two halves meeting in the B⋯B line the angle was found to be 45.0°. The cyclodiborataphosphoniane bridge shows a dynamic behaviour with an activation barrier ΔG‡ = 70 kJ mol−1 for the breaking of a PB bond. When the boron and phosphorus atoms are not directly attached to each other, but separated by an amino group (BRNPhPPh2), no donor-acceptor pairing takes place (2,3). The ligand properties of 1 and 2 towards the Cr(CO)5 fragment have been investigated.