139870-66-9Relevant academic research and scientific papers
Synthesis and characterization of Re(VII) alkylidene alkylidyne complexes of the type Re(CR′)(CHR′)(OR)2and related species
Toreki, Robert,Schrock, Richard R.,Davis, William M.
, p. 3367 - 3380 (2007/10/02)
A convenient one pot synthesis of Re(NAr)2(py)Cl3 consists of addition of excess trimethylchlorosilane, pyridine, and 2,6-dimethylaniline (ArNH2) to Re2O7 or [NH4][ReO4] in dichloromethane. Re(N-2,6-C6H3-i-Pr2)2(py)Cl 3 and Re(N-t-Bu)2Cl3 can be prepared similarly in high yield. Alkylation of these species with dineopentyl or dineophyl zinc or Grignard reagents affords complexes of the formula Re(NR)2(CHR′)(CH2R′) (R = 2,6-C6H3Me2, 2,6-C6H3-i-Pr2 or terf-butyl; R′ = CMe3 or CMe2Ph). Treatment of Re(NR)2(CHR′)(CH2R′) complexes with an appropriate HCl source yields dimers of the general formula [Re(CR′)(CHR′)(RNH2)Cl2]2, which exist as a mixture of two isomers. An X-ray study of [Re(C-t-Bu)(CH-t-Bu)(ArNH2)Cl2]2 (a = 10.05 (1) ?, b = 21.65 (3) ?, c = 10.99 (1) ?, β= 98.28 (9)°, Z = 2, fw = 1031.08, (calcd) = 1.446 g/cm3, space group = P21/n) showed it to contain two bridging halides with mutually cis alkylidene and alkylidyne ligands trans to the bridging halides. Several monomeric derivatives having the general formula Re(C-t-Bu)(CH-t-Bu)L2Cl2 (L = t-BuNH2, pyridine, 1/2TMEDA, 1/2phenylenediamine (pda)) were prepared, and related monoadducts, Re(C-t-Bu)(CH-t-Bu)(L)Cl2, have been observed in solution. Treatment of Re(C-t-Bu)(CH-t-Bu)(pda)Cl2 with HCl(g) in dimethoxyethane affords air- and water-stable [Re(C-t-Bu)(CH-t-Bu)Cl2]x (x > 1). An alternative route to [Re(C-t-Bu)(CH-t-Bu)Cl2]x consists of treatment of Re(O)2(CH-t-Bu)(CH2-t-Bu) with HCl(g) in dimethoxyethane. Re(O)2(CH-t-Bu)(CH2-t-Bu) is prepared by the acid-catalyzed hydrolysis of Re(NAr)2(CH-t-Bu)(CH2-t-Bu) via intermediate Re(NAr)(O)(CH-t-Bu)(CH2-t-Bu). Re(NAr)2(CH-t-Bu)(CH2-t-Bu) and Re(O)2(CH-t-Bu)(CH2-t-Bu) conproportionate in solution to give Re(NAr)(O)(CH-t-Bu)(CH2-t-Bu). [Re(C-t-Bu)(CH-t-Bu)Cl2]x is a versatile precursor to a variety of bisalkoxide complexes of the general formula Re(C-t-Bu)(CH-t-Bu)(OR)2 (OR = O-t-Bu, OCMe2(CF3), OCMe(CF3)2, O-2,6-C6H3-i-Pr2, OSi(t-Bu)3). Syn and anti rotameric forms of the Re(C-t-Bu)(CH-t-Bu)(OR)2 complexes interconvert thermally or photochemically. In syn rotamers usually JCH = 120-135 Hz and in anti rotamers JCH = 157-184 Hz. An X-ray study of syn-Re(C-t-Bu)(CH-t-Bu)[OCMe(CF3)2]2(THF) (a = 9.891 (1) ?, b = 17.543 (2) ?, c = 16.570 (2) ?, β= 95.90 (2)°, Z = 4, fw = 759.69, = 1.764 g/cm3, space group = P21/n) showed it to have a structure approximately halfway between a face-capped tetrahedron (THF trans to the neopentylidyne ligand) and a trigonal bipyramid.
