Pentamethylcyclopentadienylrhodaborane chemistry. Part 1. High-yield planned synthesis, molecular structure, and nuclear magnetic resonance properties of the ten-vertex nido-6-rhodadecaborane [(η⁵-C₅Me₅)RhB₉H₁₃]

Abstract

The dimeric pentamethylcyclopentadienylrhodium complex [{ Rh(qS-C,Me,)CI,},] is potentially a high-yield rhodaborane synthon, and reacts quantitatively with arachno- [ B, H, , ] to give [6-(q5-C, Me, ) -nido-6-RhB9H,,] as an orange-red air-stable solid, which has been examined by X-ray crystallography. Crystals are orthorhombic, space group Pbca, with a = 1 977.2(3), b = 1 440.1 (2), c = 2 450.1 (4) pm, and Z = 16; the final R factor is 0.0429 for 3 678 observed reflections. N.m.r. data are also presented and briefly discussed; these together with the molecular structure confirm the complex to be a nido-decaborane analogue in which the HB(6) unit is replaced by an isolobal and isoelectronic R h(qS-C,Me,) centre.* nido-6-(q 5-Pentamethylcyclopentadienyl)-6-rhodadecaborane. Supplementary data available (No. SUP 56414, 9 pp.

Determination of 1J(59Co–59Co) scalar coupling constants in the tetrahedral mixed-metal cluster HFeCo3(CO)10(PCyH2)(PPh2[CH2C(O)Ph]) using COSY-type NMR experiments

“…Furthermore, the COSY and DQF-COSY experiments have been used to prove the existence of a J scalar coupling between quadrupolar nuclei. These qualitative investigations concern nuclei with small quadrupolar moments which give rise to relatively narrow lines in the conventional 1D spectrum [18][19][20][21][22][23][24][25][26][27][28][29][30][31].…”

Metallaborane reaction chemistry. Part 12. Some interactions of acetylenes and isocyanides with selected metallaboranes

“…There are relationships to the proposed intermediate 19 of formulation {(C 6 Me 6 )-RuB 9 H 11 (CH 2 NMe)} discussed above (Fig. 12), which appears to have a more straightforward {-CH 2 -} methylene unit [50,51] There is now only one bridging hydrogen atom, which is associated with the {NB 4 } five-membered open face. The isocyanide carbon atom is now more intimately associated with the structure than as in compound 25, and, in general terms, a mechanism can be envisaged in which dihydrogen loss would convert a structure with the general shape of that of compound 25 (schematic V) to one with a shape like that of compound 26 (schematic VIIA).…”

“…(4) (see also Fig. 12), it is of interest to examine the corresponding reactions of the rhodium congener [6-(g 5 -C 5 Me 5 )-nido-6-RhB 9 H 13 ] (compound 16) [51]. In our hands so far this has exhibited quite a different reactivity.…”

“…[6-(g 5 -C 5 Me 5 )-nido-6-RhB 9 H 13 ] 16 (prepared as in [51]; 50 mg, 140 lmol) was dissolved in toluene (20 ml) and a solution of EtNC (15 mg, 280 lmol) in toluene (1.0 ml) was added, whereupon the colour of the solution changed from yellow to red. The reaction mixture was stirred for 45 min, the volatile components removed in vacuo, the residue dissolved in minimum CH 2 Cl 2 , and subjected to separation by preparative TLC using CH 2 Cl 2 100% as liquid phase.…”

The DQF-COSY NMR Experiment, a Way to Detect Small J Couplings in the Case of Fast Relaxing Nuclei: Application to ⁵⁹Co in the Tetrahedral Mixed-Metal Cluster HRuCo₃(CO)₁₁(PPh₃)

“…The conventional COSY NMR experiment [1] is an efficient and powerful technique to prove qualitatively the existence of a coupling constant between quadrupolar nuclei. However, most of the investigations performed so far concern nuclei with small quadrupole moments such as 11 B [2]- [10], 51 V [11], 2 H [12], 6 Li [13]- [16] and 7 Li [14]- [16], whose lines are relatively narrow in the conventional 1D spectrum. The DQF-COSY NMR experiment has only been scarcely used in the field of quadrupolar nuclei, and only when the lines were broad in the 1D spectrum [17]- [19].…”