Reactions of 6,6′-bis(nido-decaboranyl) oxide and 6-hydroxy-nido-decaborane with dihalogenobis(phosphine) complexes of nickel, palladium, and platinum, and some related chemistry; nuclear magnetic resonance investigations and the crystal and molecular structures of bis(dimethylphosphine)-di-µ-(2,3,4-η3-nido-hexaboranyl)-diplatinum(Pt–Pt), [Pt2(µ-η3-B6H9)2(PMe2Ph)2], and of 2,4-dichloro-1,1-bis(dimethylphenylphosphine)-closo-1-nickeladecaborane, [(PhMe2P)2NiB9H7Cl2]

Abstract

A modified procedure for the preparation and isolation of 6,6′-(B₁₀H₁₃)₂O leads also to the isolation of the new compound 6-B₁₀H₁₃OH, which has been fully characterised by ¹¹B and ¹H n.m.r. and mass spectroscopy. The structures and some chemistry of these two related oxyboranes are compared. The reaction of either 6,6′-(B₁₀H₁₃)₂O or 6-B₁₀H₁₃OH with cis-[Pt₂Cl₂L₂](L = PMe₂Ph or PPh₃) gives three platinaboranes, arachno-[L₂PtB₈H₁₂](1), nido-[L₂PtB₁₀H₁₂], and [Pt₂(µ-η³-B₆H₉)₂L₂](2). The yellow needles of (2)(L = PMe₂Ph) are monoclinic, space group P2₁/c, with a= 1 014.0(2), b= 586.8(2), c= 2 316.9(6) pm, β= 91.66(2)°, Z= 2 and the molecular structure is that of a centrosymmetric 14-vertex arachno-diplatinaborane in which two B₆H₉ clusters are bonded above and below an almost linear P–Pt–Pt–P system. The bonding of each B₆H₉ unit is symmetrical trihapto. In sharp contrast the reaction of 6,6′-(B₁₀H₁₃)₂O with the corresponding nickel complex cis-[NiCl₂(PMe₂Ph)₂] gives mainly phosphine–boranes of known type, viz. PhMe₂P·BH₃, PhMe₂P·B₃H₇, and PhMe₂P·B₉H₁₃, together with a low yield of the new metallaborane closo-[(PhMe₂P)₂NiB₉H₇C₁₂](3). The red crystals of (3) are monoclinic, space group C2/c, with a= 1 341.2(2), b= 1 321.5(2), _c= 1 476.3(2) pm, β= 109.50(1)°, Z= 4 and the molecular structure is that of a bicapped square antiprismatic 1 0-vertex close-nickelaborane in which the Ni(PMe₂Ph)₂ group takes up a capping four-connected site. The reaction of 6,6′-(B₁₀H₁₃)₂O with cis-[PdCl₂L₂](L = PMe₂Ph or PPh₃) gives phosphine-boranes analogous to those from the reaction with cis-[NiCl₂(PMe₂Ph)₂], together with arachno-[L₂PdB₈H₁₂], the palladium analogues of (1). Treatment of (1) with KH followed by cis-[ PdCl₂(PMe₂Ph)₂] gives the moderately stable heterodimetallaborane cluster compound, [(PhMe₂P)₄PdPtB₈H₁₀], an arachno-palladaplatinaborane species and the first metallaborane of any kind to contain metals from two different periods in the Periodic Table. Treatment of (2) with base followed by cis-[ PdCl₂(PMe₂Ph)₂] gives the 15-vertex trimetallaborane cluster compound [ Pt₂(µ-η³- B₆H₉)(µ-{η³- B₆H₈-η²- PtH (PMe₂Ph)₂})(PMe₂Ph)₂]. The ¹H, ¹¹B, and ³¹P n.m.r. behaviour of these compounds have been investigated in detail using both single- and double-resonance techniques, and a number of interesting patterns emerge.