Some palladium(II) and platinum(II) derivatives of pentaborane(9)

Abstract

Metathesis of potassium nido-octahydropentaborate, K[B₅H₈], with numerous cis-bis(phosphine) complexes of palladium(II) and platinum(II) halides affords cis-[M(B₅H₈)(PR₃)₂X] in good yields (X = Cl, Br, I, or Me; PR₃= PPh₃, PMe₂Ph, PMe₃, or ½Ph₂PCH₂CH₂PPh₂). The platinum complexes are more stable than those of pailadium and can be stored unchanged for long periods at room temperature. Similar reactions with appropriate starting materials lead to cis-[Pt(B₅H₈)Cl(AsPh₃)₂], cis-[{Pt(B₅H₈)(PMe₂Ph)(µ-SMe)}₂], and the less-stable trans-[Pt(B₅H₈)I(PMe₂Ph)₂] and trans-[Pt(B₅H₈)Me(PMe₂Ph)₂]. In all cases the B₅H₈ ligand is η²-bonded to the metal via two of the basal boron atoms B(2) and B(3). Hydrogen-1, ¹¹B, ³¹P, and ¹⁹⁵Pt n.m.r. data for the cis complexes are discussed in terms of the detailed geometrical structure and the nature of the metal–borane bonding.