Cyclooctadiene Rh(I) Bis- and Tris(pyrazolyl)aluminate Complexes and Their Catalytic Activity on the Polymerization of Phenylacetylene

In this work, we report the transfer of alkyl bis- and tris(pyrazolyl)aluminates metalloligands to an electron-rich organotransition metal center. The 16-electron heterobimetallic complexes rhodium [Rh(COD){Al(Ph2pz)2Me2}] (3) [Rh(COD){Al(Ph2pz)3Me}] (4) were obtained by metathesis reaction sodium (1) tris(pyrazolyl)aluminate (2) with [RhCl(COD)]2. For 3, 1H 13C NMR in solution along DFT calculations are consistent a ?2-coordination mode bis(pyrazolyl)aluminate square-planar Rh(I) X-ray structure 4 shows similar pendant pyrazolyl moiety. attempted synthesis aluminate-rhodium R = CF3, tBu on pyrazolate ring afforded [Rh(R2pz)(COD)]2 [R2pzAlMe2]2. Complexes 3 investigated as homogeneous catalysts polymerization phenylacetylene (PA). Both showed enhanced catalytic activity compared analogous poly(pyrazolyl)borates. Optimized gas-phase geometries 4, [Rh(COD){B(Ph2pz)2Me2}], [Rh(COD){B(Ph2pz)3Me}] used compare bite angles, while 3-CO, 4-CO, [Rh(CO)2{B(Ph2pz)2Me2}], [Rh(CO)2{B(Ph2pz)3Me}] employed probe electronic situation center through IR CO stretching modes. wider angles less poly(pyrazolyl)aluminates their borate analogues could be implicated better performance active species during PA.