Rhodium halo salts

The dimeric tetraacetato bridged Rh2(OCOCH3)4 has been obtained by the interaction of ammonium chlororhodate(III) or rhodium (III) hydroxide with acetic acid.1-3 Other (car-boxylato)rhodium(II) compounds were prepared directly in a similar way or from the acetate by exchange.2,3 Halo car-boxylates (RCOO, R = CC13, CF3, CH2C1, etc.) were prepared also by interaction of rhodium trichloride with the appropriate sodium salt in ethanol.4 The carboxylatcs are normally first isolated as a solvent adduct, e.g., [Rh(OCOR)2-C2H5OH]2 but are easily converted to the unsolvated complex. The acetate is readily prepared in a modification of this last procedure. A similar method is satisfactory for the preparation of other lower carboxylates as well as halo carboxylates. 

Relatively little has appeared in the past year on the synthesis and reactivity of the six membered, potentially aromatic, phosphinine ring system. A route to the first C2-asymmetric phosphinine (147), derived from (+ )-camphor, has been developed from the reaction of a pyrylium salt precursor with P(TMS)3. The chiral phosphinine is a crystalline, air-stable solid and forms complexes with metal ions, therefore having some potential as a ligand in homogeneous eatalysis." A pyrylium salt-P(TMS)3 final step was also used in the synthesis of a series of 2-(2 -halo)triarylphosphinines (148), subsequently shown to form a series of tungsten(0) and rhodium(I) complexes involving coordination of the phosphorus sp lone pair to the metal." Interest has continued in studies of the coordination chemistry of phosphabarrelenes, derived from the established reactions of phosphinines... 

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