The reactivity of Lewis base stabilized pnictogenylboranes towards transition metal complexes has been investigated.

Reaction of Lewis base stabilized phosphinoborane monomer tBuHPBH2NMe3 with catalytic amounts of bis(η5:η1-adamantylidenepentafulvene)titanium provide a convenient new route to polyphosphinoboranes [tBuPH-BH2]n. This method offers access to high molecular mass materials under mild conditions and short reaction times. It represents an unprecedented example of a transition-metal mediated polymerization of Lewis base stabilized Group 13/15 compounds. For this reaction a variety of different monomers of the type RR’EBH2NMe3 (E = P, As; R/R’ = H, alkyl, aryl) has been tested.

The structural and photophysical properties of a series of new Au(I) compounds have been studied. The reactions of AuCl(tht) with the phosphanyl- and arsanylboranes RR’EBH2NMe3 (E = P, As; R = H, Ph; R’ = H, Ph, tBu) afford the complexes [AuCl(RR’EBH2NMe3)]. In the solid state, [AuCl(H2PBH2NMe3)]2 is a dimer showing unsupported intermolecular aurophilic interactions with short Au…Au distances. In contrast, [AuCl(H2AsBH2NMe3)]n aggregates to form 1D chains. Organic substituents on the pnictogen atoms lead to discrete molecules in [AuCl(RR’PBH2NMe3)] (R = H, R’ = tBu or R = R’ = Ph). To increase the aurophilicity, the ionic homoleptic complexes [Au(RR’EBH2NMe3)2][AlCl4] have been synthesized for which 3a,b form chains in the solid state and exhibit luminescence. The emissions show a drastic redshift with temperature decrease correlating with decreasing Au...Au distances. DFT calculations provide insight into the bonding situation of the products.

Reactions of the pnictogenylboranes H2EBH2·NMe3 (E = P, As) and Ph2PBH2·NMe3 with [Cu(MeCN)4][BF4] afford the homoleptic complexes [Cu(H2EBH2·NMe3)4(BF4)] (E = P, As) and [Cu(Ph2PBH2·NMe3)3][BF4]. Compound [Cu(H2AsBH2·NMe3)4(BF4)] represents the first structurally characterized complex of a primary arsine coordinated to a Cu center. From reactions of Ph2PBH2·NMe3 with CuX, a series of 10 complexes [CunXn(Ph2PBH2·NMe3)m] (X = Cl, Br, I; n = 1-6, m = 2-4) were synthesized and compared to related complexes possessing Ph3P ligands. All complexes were characterized by single-crystal X-ray structure analysis, multinuclear NMR spectroscopy, IR spectroscopy and mass spectrometry.