Preparation and nuclear magnetic resonance properties of eleven-vertex closo-type osmaundecaboranes and the X-ray crystal structure of the ortho-cycloboronated compound [2,5-(OEt)2-1-(PPh3)-1-(o-Ph2PC6H4)-closo-1-OsB10H7-3]

Abstract

Reaction of the osmium(III) species [OsCl₃(PMe₂Ph)₃] with closo-[B₁₀H₁₀]^2– in EtOH gives red-orange [(PMe₂Ph)₂OsB₁₀H₈(OEt)₂](42%) identified by n.m.r. spectroscopy. By contrast, a similar procedure with the osmium(II) species [OsCl₂(PPh₃)₃] gives the P–phenylene ortho-cycloboronated amber-brown compound [(PPh₃)(Ph₂P[graphic omitted]H₇(OEt)₂](39%), identified by single-crystal X-ray crystallography. Crystals are monoclinic, space group P2₁/n, with a= 1 123.7(1), b= 2 092.4(3), c= 1 750.9(2) pm, β= 92.54(1)°, and Z= 4; the final R factor is 0.0283 for 4 623 observed reflections. These new eleven-vertex osmaboranes are air-stable as solids, and have closed eleven-vertex 1-metallaundecaborane geometries for which ‘isocloso’ electronic configurations have been proposed.