Pentamethylcyclopentadienylrhodaborane chemistry. Part 2. The reaction of [6-(η5-C5Me5)-nido-6-RhB9H13] with dimethylphenylphosphine, and the characterization of [5-(η5-C5Me5)-nido-5-RhB9H11-7-(PMe2Ph)], [2-(η5-C5Me5)-closo-2-RhB9H7-3,10-(PMe2Ph)2],* and [2-(η5-C5Me5)-nido-2-RhB8H10-5-(PMe2Ph)] by X-ray diffraction analysis and nuclear magnetic resonance spectroscopy

Abstract

Reaction of [6-(η⁵-C₅Me₅)-nido-6-RhB₉H₁₃](1) with an excess of PMe₂Ph in CH₂Cl₂ solution at room temperature yields three air-stable compounds: red-orange [5-(η⁵-C₅Me₅)-nido-5-RhB₉H₁₁-7-(PMe₂Ph)](2; 35%), yellow [2-(η⁵-C₅Me₅)-closo-2-RhB₉H₇-3,10-(PMe₂Ph)₂](3; 25%), and orange [2-(η⁵-C₅Me₅)-nido-2-RhB₈H₁₀-5-(PMe₂Ph)](4; ca. 7%). Crystals of (2) are triclinic, space group P, with a= 940.9(2), b= 875.2(2), c= 1 561.4(2) pm, α= 99.06(2), β= 103.45(1), γ= 91.57(2)°, and Z= 2. Crystals of (3) are monoclinic, space group P2₁/a, with a= 1 406.4(3), b= 1 231.7(3), c= 1 812.3(3) pm, β= 94.01 (1)°, and Z= 4. These compounds, and compound (4), were also characterized by n.m.r. spectroscopy. Structural and bonding considerations are discussed and some mechanistic implications are briefly considered.