PROTONATION REACTIONS OF THE SALTS [NA][PT(PR3)(2)(ETA(5)-7-CB10H11)](PR3 = PET3 OR PME2PH) - SYNTHESIS AND CRYSTAL-STRUCTURES OF THE PLATINACARBORANE COMPLEXES [PTCL(PME2PH)(2)(ETA(5)-7-CB10H11)], [PT-2(MU-SIGMA,ETA(5) SIGMA',ETA(5)'-8,9'-(7-CB10H10)(2))(PME2PH)(4)] AND PET3)(4)(ETA(5)/ETA(5)'-9,9'-I(H)(7-CB10H10)(2))]/

Protonation of [Na][Pt(PMe2Ph)(2)(eta(5)-7-CB10H11)] 1b with HCl in di ethyl ether afforded a mixture of the complexes [PtX(PMe2Ph)(2)(eta(5) -7-CB10H11)] (X = H 2b or Cl 3) and [Pt-2{mu-sigma,eta(5) : sigma' eta (5)'-8,9'-(7-CB10H10)(2)}(PMe2Ph)(4)] 4. Single-crystal X-ray diffract ion studies established the structures of 3 and 4. In the former the p latinum atom is coordinated on one side by the open CBBBB face of the nido-7-CB10H11 cage and on the other by a chlorine atom and two PMe2Ph molecules. In the molecule 4 two nido-icosahedral CB10 cage framework s, each eta(5)-co-ordinated by their open CBBBB faces to a platinum at om, are joined by a B-B connectivity and by two relatively long Pt-B c onnectivities. The B-B link is formed between a boron atom in a beta s ite in one CBBBB ring and a boron in an alpha site in the other CBBBB ring. Each boron involved in this connectivity also forms a B-Pt linka ge to the platinum atom in the adjacent closo-2,1-PtCB10 sub-cluster. Thus the two metal atoms and the two borons form a 'butterfly' arrange ment with the platinums at the wing-tips. Treatment of [Na][Pt(PEt3)(2 )(eta(5)-7-CB10H11)] with HCl in diethyl ether gave [PtH(PEt3)(2)(eta( 5)-7-CB10H11)] 2a as expected, but a complex mixture of other products was also formed. Addition of [NEt4]I to this mixture allowed isolatio n of a species [Pt-2(PEt3)(4)(eta(5) : eta(5)'-9,9'-I(H)(7-CB10H10)(2) }] 5. This unusual formulation is based principally on the results of an X-ray diffraction study which revealed that two icosahedral closo-2 ,1-PtCB10 sub-clusters were bridged by an iodine atom.