433713-03-2Relevant articles and documents
Pyridylazole chelation of oxorhenium(V) and imidorhenium(V). Rates and trends of oxygen atom transfer from ReVO to tertiary phosphines
Gangopadhyay, Jaydip,Sengupta, Suman,Bhattacharyya, Sibaprasad,Chakraborty, Indranil,Chakravorty, Animesh
, p. 2616 - 2622 (2002)
The concerned azoles are 2-(2-pyridyl)benzoxazole (pbo) and 2-(2-pyridyl)benzthiazole (pbt). These react with ReOCI3(PPh3)2 in benzene, affording ReVOCI3(pbo) and ReVOCI3(pbt), which undergo facile oxygen atom transfer to PPh2R (R = Ph, Me) in dichloromethane solution, furnishing ReIII(OPPh2R)CI3(pbo) and ReIII(OPPh2R)CI3(pbt). The oxo species react with aniline in toluene solution, yielding the imido complexes ReV(NPh)CI3(pbo) and ReV(NPh)CI3(pbt). The X-ray structures of pbt, ReOCI3(pbt), Re(OPPh3)CI3(pbt), and Re(NPh)CI3(pbo) are reported. The lattice of pbt consists of stacked dimers. In all the complexes the azole ligand is N,N-chelated and the ReCI3 moiety is meridionally disposed. In ReOCI3(pbt) the metal-oxo bond length is 1.607(9) A. The second-order rates and the associated activation parameters of the oxygen atom transfer reactions of the ReVO chelates with PPh2R are reported. The large and negative entropy of activation (～ -24 eu) is consistent with an associative pathway involving nucleophilic phosphine attack. The rate increases with phosphine basicity (PPh2Me > PPh3) and azole heteroatom electronegativity (O(pbo) > S(pbt)). Logarithmic rate constants for ReOCI3(pbo), ReOCI3(pbt), and ReOCI3-(pal) are found to correlate linearly with ReVIO/ReVO reduction potentials (pal is pyridine-2-(N-tolyl)aldimine). The relatively low rate constant of ReOCI3(pbt) compared to that of ReOCI3(pal) is consistent with the observed shortness of the metal-oxo bond in the former. Crystal data are as follows: (pbt) empirical formula -C12H8N2S, crystal system orthorhombic, space group Pca21, a = 13.762(9) A, b = 12.952(8) A, c = 11.077(4) A, V = 1974(2) A3, Z = 8; (ReOCI3(pbt)) empirical formula C12H8CI3N2OSRe, crystal system monoclinic, space group P21/c, a = 11.174(7) A, b = 16.403(10) A, c = 7.751(2) A, β = 99.35(4)°, V = 1401.8(13) A3, Z = 4; (Re(NPh)CI3(pbo)) empirical formula C18H13CI3N3ORe, crystal system monoclinic, space group P21/c, a = 9.566(6) A, b = 16.082(8) A, c = 11.841(5) A, β = 94.03(4)°, V = 1817(2) A3, Z = 4.
