Protonation reactions of the salts [Na][Pt(PR3)2(η5-7-CB10H11)] (PR3 = PEt3 or PMe2Ph): synthesis and crystal structures of the platinacarborane complexes [PtCl(PMe2Ph)2(η5-7-CB10H11)], [Pt2{μ-σ,η5∶σ′,η5′-8,9′-(7-CB10H10)2}(PMe2Ph)4] and [Pt2(PEt3)4{η5∶η5′-9,9′-I(H)(7-CB10H10)2}] †

Abstract

Protonation of [Na][Pt(PMe 2 Ph) 2 (η 5 -7-CB 10 H 11 )] 1b with HCl in diethyl ether afforded a mixture of the complexes [PtX(PMe 2 Ph) 2 (η 5 -7-CB 10 H 11 )] (X = H 2b or Cl 3) and [Pt 2 {µ-σ,η 5 : σЈ,η 5 Ј-8,9Ј-(7-CB 10 H 10 ) 2 }(PMe 2 Ph) 4 ] 4. Singlecrystal X-ray diffraction studies established the structures of 3 and 4. In the former the platinum atom is coordinated on one side by the open CBBBB face of the nido-7-CB 10 H 11 cage and on the other by a chlorine atom and two PMe 2 Ph molecules. In the molecule 4 two nido-icosahedral CB 10 cage frameworks, each η 5 -co-ordinated by their open CBBBB faces to a platinum atom, are joined by a B᎐B connectivity and by two relatively long Pt᎐B connectivities.The B᎐B link is formed between a boron atom in a β site in one CBBBB ring and a boron in an α site in the other CBBBB ring. Each boron involved in this connectivity also forms a B᎐Pt linkage to the platinum atom in the adjacent closo-2,1-PtCB 10 sub-cluster. Thus the two metal atoms and the two borons form a 'butterfly' arrangement with the platinums at the wing-tips. Treatment of [Na][Pt(PEt 3 ) 2 (η 5 -7-CB 10 H 11 )] with HCl in diethyl ether gave [PtH(PEt 3 ) 2 (η 5 -7-CB 10 H 11 )] 2a as expected, but a complex mixture of other products was also formed. Addition of [NEt 4 ]I to this mixture allowed isolation of a species [Pt 2 (PEt 3 ) 4 {η 5 : η 5 Ј-9,9Ј-I(H)(7-CB 10 H 10 ) 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-PtCB 10 sub-clusters were bridged by an iodine atom.

Electronic Requirements for Macropolyhedral Boranes

“…In such complexes it is clear that the electrons in the multicenter bonding are involved in skeletal bonding. However, in metallaboranes it appears as though they are separate entities …”

Synthesis of Nickel−Monocarbollide Complexes by Oxidative Insertion

“…It was of interest to further investigate the protonation reactions of compound 1a and its analogues beyond those preliminary studies that gave rise to compounds 2a and 2b . It has previously been observed that whereas most { closo -MCB 10 H 11 } anions (M = Mo, , W, Fe, , and Co 15 ) undergo cage boron hydride abstraction upon protonation, for M = Pt protonation typically occurs at the metal center, forming Pt−H species. , Although compound 1a is quite stable, in contrast with the above reactions of 1b and 1c , attempted protonation of compound 1a led to decomposition via rapid CO evolution and formation of an intractable mixture in which the only identifiable species was the [ closo -2-CB 10 H 11 ] - anion, detected by 11 B{ 1 H} NMR spectroscopy. It is thought that in any initially formed products, which would presumably be neutral, the CO ligands are extremely labile and, thus, rapidly lost.…”

Construction of Metal Butterflies on a Metallacarborane Scaffold. 1. Synthesis and Structures of Bimetallic Precursors

“…While this feature may be useful in stabilizing the often unusual oxidation states accessible in such species, − its main utility lies in their reactions with electrophiles . With H + , for example, the metal center may simply be protonated to form a metal-hydride species, or the proton may behave as a hydride abstractor and thereby facilitate substitution at a {BH} vertex. − ,− Alternatively, when the electrophile is a cationic transition metal−ligand fragment, species containing multiple metal centers can result. ,5a,,,− …”