Synthesis and crystal structures of the complexes [RhPt(µ-H)(µ-CO)(PEt₃)₂(PPh₃)(η⁵-C₂B₉H₁₁)] and [RhPt{σ-C(C₆H₄Me-4)C(C₆H₄Me-4)H}(CO)(PEt₃)(PPh₃)(η⁵-C₂B₉H₁₁)]

Synthesis of Mixed-Metal (Ru−Rh) Bimetallacarboranes viaexo-nido- andcloso-Ruthenacarboranes. Molecular Structures of (η4-C8H12)Rh(μ-H)Ru(PPh3)2(η5-C2B9H11) and (CO)(PPh3)Rh(μ-H)Ru(PPh3)2(η5-C2B9H11) and Their Anioniccloso-Ruthenacarborane Precursors

“…In fact, the Rh atoms are displaced from the least-squares planes including H(br)H(8)C(12M)C(56M) [C(12M) and C(56M) are the midpoints of the double bonds C(1)C(2) and C(5)C(6) in COD] and H(br)H(8)C(O)P(3) by 0.08 and 0.03 Å in 4 and 10 , respectively. Similar square-planar coordination around 16-electron metal centers was observed earlier for [RuRh(μ-Cl)(μ-H)(η 4 -COD)(dppm)]BF 4 , [Rh 2 (CO) 2 (PPh 3 ) 2 (η 5 -7,8-C 2 B 9 H 11 ), or RhPt(μ-H)(μ-CO)(PEt 3 )(PPh 3 )(η 5 -7,8-C 2 B 9 H 11 ), wherein the existence of a metal−metal bond has been assumed. In addition, according to the electron-counting formalism adopted for bimetallic complexes with bridging hydride ligands, compounds 4 and 10 should be considered as unsaturated species having 32 valence electrons, and it seemed, therefore, that there also should be a single metal− metal bond in these complexes.…”

“…As previously reported for a Rh−Ir cluster [RhIrH(μ−σ:η 5 -C 2 B 9 H 10 )(CO) 3 (PPh 3 ) 2 ], which contains a Ir−H terminal bond and at least one PPh 3 ligand at each of the metal centers, no additional splitting of this hydride resonance due to 1 H− 31 P(Rh) as well as 1 H− 103 Rh was observed in the 1 H NMR spectrum. At the same time, in the 1 H NMR spectrum of the bimetallic compound [RhPt(μ-H)(μ-CO)(PEt 3 )(η 5 -C 2 B 9 H 11 )], wherein the Rh−Pt unit is bridged by a hydrido ligand, the high-field resonance of this ligand was split by the three nonequivalent 31 P nuclei of the phosphine ligands attached to the different metal centers and by the 103 Rh nucleus as well. Additionally, examination of the 1 H{ 31 P} NMR spectrum of 4 revealed a doublet instead of a pseudoquartet in the same region, which was attributed to 1 H− 103 Rh coupling ( J H - Rh = 20.4 Hz).…”

“…Since structural characterization of the first two bimetallic rhodacarboranes [(Ph 3 PRhC 2 B 9 H 11 ] 2 1 and [(Et 3 P)RhC 2 B 9 H 10 ] 2 2 demonstrated their unique nature of bonding via exopolyhedral two-electron three-center (2e,3c) B−H···M bonds supporting the Rh−Rh single bond in the dimers, the chemistry of low-nuclearity homo- and heterometallic carborane-containing clusters has been extensively studied . Within this family numerous examples of homo- and mixed-metal bimetallacarboranes of the platinum group with Rh−Rh, − Rh−Ir, Rh−Pt, and other Rh−M fragments 5 , ,− have recently been synthesized and structurally characterized. All these species, however, are formally closo -rhodacarboranes since the dicarbollide ligand is η 5 -coordinated to the rhodium atom while the latter is simultaneously linked to a variety of other transition metals.…”

Hydrocarbyl Ligand Transformations on Heterobimetallic Complexes

“…Terminal platinum-bonded alkenyl complexes 331 with the expected stereochemistry (H cis to the Pt atom) ensue. There is an “agostic” B−H interaction from the carborane ligand to the electron-deficient platinum atom 202 Alkenyl Formation in a Platinum−Rhodium μ-Hydride Complex …”