53495-46-8Relevant articles and documents
Chemistry of coordinated nitroxyl. Reagent-specific protonations of trans-Re(CO)2(NO)(PR3)2 (R = Ph, Cy) that give the neutral nitroxyl complexes cis,trans-ReCl(CO)2(NH=O)(PR3)2 or the cationic hydride complex [trans,trans-ReH(CO)2(NO)(PPh3)2 +][SO3CF3-]
Southern,Green,Hillhouse,Guzei,Rheingold
, p. 6039 - 6046 (2008/10/08)
The reactions of hydrochloric and triflic acids with the five-coordinate nitrosyl complexes trans-Re(CO)2(NO)(PR3)2 (2a, R = Ph; 2b, R = Cy) have been investigated. Reaction of anhydrous HCl with 2 results in a formal protonation of the nitrosyl ligand and addition of chloride to the metal, giving the neutral nitroxyl complex cis,trans-ReCl(CO)2(NH=O)(PR3)2 (3a, R= Ph; 3b, R = Cy). Reaction of Bronsted bases with 3a or 3b results in clean conversion of 3 to 2 when the base is appropriately strong (pKb ? 7). Addition of HOSO2CF3 to solutions of 2a results in protonation at the metal and formation of the cationic rhenium hydride [trans,trans-ReH(CO)2(NO)(PPh3)2 +][SO3CF3-] (4) in 74% yield; the deuteride [trans, trans-Re(2H)(CO)2(NO)(Pph3)2 +][SO3CF3-] (4-d) was analogously prepared from 2HOSO2CF3. 4 crystallized from CH2Cl2/Et2O solution in the orthorhombic space group Pnma, with a = 17.2201(2) A, b = 23.6119(3) A, c = 9.2380(2) A, and Z = 4. The least-squares refinement converged to R(F) = 0.039 and R(wF2) = 0.063 for the 4330 unique data with I > 2σ(I). The structure of 4 shows that the hydride (Re - H = 1.74 A) occupies the position trans to the linear nitrosyl ligand (Re - N - O = 178.1(4)°) in the pseudooctahedral complex cation. Complex 4 does not react with chloride to give 3a. DFT calculations carried out on free nitroxyl and its model complexes [Re(CO)5(NH=O)+] (5), [mer, trans-Re(CO)3(NH=O)(PH3)2+] (6), and cis,trans-ReCl(CO)2(NH=O)(PH3)2 (7) indicate that coordinated nitroxyl acts as both a σ-donor and π-acceptor ligand, consistent with the observed trend for ν(NO) in free HN=O (1563 cm-1), [mer,trans-Re(CO)3(NH=O)(PPh3)2+] (1, 1391 cm-1), 3a (1376 cm-1), and 3b (1335 cm-1).
Nitrosyl complexes of rhenium. Synthesis of some fluoro complexes of rhenium(I), including the novel cationic complex fluorocarbonylnitrosyltris(triphenylphosphine)rhenium(I) tetrafluoroborate
Stanley Cameron,Grundy, Kevin R.,Robertson, Katherine N.
, p. 4149 - 4155 (2008/10/08)
The complex previously reported as ReCl2(NO)(PPh3)2 has been reformulated as a methoxide complex, ReCl2-(OCH3)(NO)(PPh3)2. ReCl2(OCH3)(NO)(PPh3)2 reacts with NaBH4 and PPh3 in ethanol to give much improved yields of ReH2(NO)(PPh3)3. ReH2(NO)(PPh3)3 reacts with HCl in ethanol suspension to form air-sensitive ReCl2(NO)(PPh3)3, which in turn reacts with CO or CNR (R = p-tolyl) to give ReCl2(CO)(NO)(PPh3)2 and ReCl2(CNR)2(NO)(PPh3), respectively. ReH2(NO)(PPh3)3 reacts with HBF4 (or HPF6) in the presence of CO to give the novel fluoro cation [ReF(CO)(NO)(PPh3)3]+, which reacts with certain coordinating anions to give neutral ReXF(CO)(NO)(PPh3)2 (X = H, OCH3, F). ReHF(CO)(NO)(PPh3)2 is unusual in that its stereochemistry can be determined absolutely by a combination of IR and 1H NMR spectroscopy. The structure has been determined of fluorocarbonylnitrosyltris(triphenylphosphine)rhenium(I) perchlorate, prepared from [ReF(CO)(NO)(PPh3)3]BF4 and NaClO4 in ethanol. Solvated crystals of [ReF(CO)(NO)(PPh3)3]ClO4 from dichloromethane-cyclohexane are monoclinic, with a = 14.981 (2) ?, b = 25.560 (3) ?, c = 15.133 (4) ?, β = 104.84°, space group P21/n, and Z = 4. Data were collected by four-circle diffractometry with 2092 reflections with I > σ(I) being observed. Refinement was by large-block least squares to R = 0.057. The unit cell contains molecules of crystallization disordered about a center of symmetry. There appears to be a random mixture of cyclohexane and dichloromethane, and atomic locations have not been assigned to the solvent atoms. The structure of the cation is that of a distorted octahedron with a meridional array of phosphine ligands and the fluoride ligand (r(ReF) = 1.973 (13) ?) trans to the linear nitrosyl group.
