91580-98-2Relevant academic research and scientific papers
Synthesis of [Rh2(μ-OR)(CO)2(μ-PPh2CH 2PPh2)2]ClO4 (R = H, CH3, C2H5) and their use as synthetic precursors to other A-frame complexes
Deraniyagala, Samitha P.,Grundy, Kevin R.
, p. 50 - 56 (2008/10/08)
General preparative methods for the synthesis of a variety of A-frame complexes, [Rh2(μ-X)(CO)2(μ-dppm)2]+, are presented, including examples in which the bridgehead ligand X has an oxygen or nitrogen donor atom. The reaction of trans-[Rh2Cl2-(CO)2(μ-dppm)2] with excess RO- and NaClO4 in the appropriate alcohol suspension yields [Rh2(μ-OR)(CO)2(μ-dppm)2]ClO4 (R = Me, Et). Recrystallizing the alkoxide complexes in the presence of excess HClO4 gives [Rh2(μ-OH)(CO)2(μ-dppm)2]ClO4. A similar hydroxide complex [Rh2(μ-OHCl)(CO)2(μ-dppm)2]·H 2O results from the reaction of trans-[Rh2Cl2(CO)2(μ-dppm)2] with Na2CO3 in aqueous ethanol. The bridging ligands in [Rh2(μ-OR)(CO)2(μ-dppm)2]ClO4 (R = H, Me, Et) are acid labile, enabling a range of substitution reactions to be performed. Thus, complexes of the type [Rh2(μ-X)(CO)2(μ-dppm)2]ClO4 with X = Cl, Br, I, O2CH, O2CCH3, O2CCF3, NCO, and N3 can be synthesized. The trifluoroacetate group in [Rh2(μ-O2CCF3)-(CO) 2(μ-dppm)2]ClO4 is also labile, making this compound a useful synthon. With excess MX, complexes of the type [Rh2(μ-N3)(CO)2(μ-dppm) 2]ClO4 and [RhX(CO)(dppm)]2 (X = NCO, NCS) can be isolated. With 1 equiv of NH4NCS, [Rh2(μ-O2CCF3)(CO) 2(μ-dppm)2]ClO4 yields [Rh2(μ-NCS)(CO)2(μ-dppm)2]ClO 4. The N-bound isomer is also obtained when [Rh2-(μ-OEt)(CO)2(μ-dppm)2]ClO 4 reacts with NH4NCS in the presence of HClO4, but when the acid is omitted, the S-bound isomer [Rh2(SCN)(CO)2(μ-dppm)2]ClO4 results.
