Stereoisomerism of oxotrichlorobis(triphenylphosphine)rhenium(V), ReOCl₃(PPh₃)₂: a reinvestigation

Abstract

The various preparative procedures described in the literature for ReOCl,(PPh,), were rep~ated. The standard methods were found to yield a yellow triclinic material ( P l , a = 11.793, b = 14.300, c = 16.422 A, a = 64.04", P = 84.31°, y = 87.32", R = 0.064). The unit cell contains three discrete monomeric molecules with the trans-bis(phosphine) configuration, one of which has its C1-Re=O unit disordered over two opposite directions. Recrystallization in CH2C1, yielded crystals of the bright green monoclinic polymorph (C2/c, a = 24.347, b = 9.604, c = 15.666 A, P = 1 16.77", R = 0.025) containing the same monomeric molecule, but with a different conformation of the PPh, ligands and a different packing pattern. These two polymorphs actually correspond to "isomers" 1 and 2 described by Johnson, Lock, and Wilkinson in 1964. Attempts to prepare their third "isomer" yielded powders containing ReOC13(PPh3)2 (green polymorph) and ReNC1,(PPh3)2. The IR and ,'P NMR spectra of these samples are discussed. ANNE-MARIE LEBUIS et

(OC-6-14)-(7-Azaindole)dichloro(ethoxo)oxo(triphenylphosphine)rhenium(V)

“…Our Re---P distance [2.463 (2)]q is close to those found in both forms of the compound [2.465 (2) for (I), 2.482 (3)A for (II)]. This is definitely short when compared to those of bis(triphenylphosphine)-Re v complexes [2.52-2.55 A (Lebuis & Beauchamp, 1993a;Lebuis, Roux & Beauchamp, 1993;Ciani, D'Alfonso, Romiti, Sironi & Freni, 1983;Graziani, Casellato, Rossi & Marchi, 1985)]. On the other hand, the Re--N distance [2.185 (7) A] is significantly longer than those found for [ReC120(C2HsO)L2] with L= py [2.144 (7)A (Lock & Turner, 1977)] and L = Haza [2.136 (8) A (Lebuis & Beauchamp, 1993b)].…”

“…On the other hand, the Re--N distance [2.185 (7) A] is significantly longer than those found for [ReC120(C2HsO)L2] with L= py [2.144 (7)A (Lock & Turner, 1977)] and L = Haza [2.136 (8) A (Lebuis & Beauchamp, 1993b)]. The Re C1 distances are unequal [Re--CI(1) = 2.427 (2), Re C1(2) = 2.385 (2)A], but within the range (2.37-2.44A) observed for a series of ReV-mono-oxo complexes (Ehrlich & Owston, 1963;Sergienko & PoraiKoshits, 1982;Lebuis & Beauchamp, 1993a (Ciani et al, 1983;Lebuis & Beauchamp, 1993a,b;Graziani et al, 1985;Lock & Turner, 1977). The terminal atom C(41) in the ethyl group has large thermal parameters, but no resolved disorder was detected.…”

Oxo and Imido Complexes of Rhenium and Molybdenum in Catalytic Reductions

“…A series of imido and nitrido rhenium(V) catalysts (25)(26)(27)(28)(29)(30) have been examined and compared to their oxo analogues [17]. The imido compounds (25)(26)(27)(28) are comparable or more active than their oxo counterparts in aldehyde hydrosilylation; notably an amine-substituted complex 28 is quite effective.…”

“…The imido compounds (25)(26)(27)(28) are comparable or more active than their oxo counterparts in aldehyde hydrosilylation; notably an amine-substituted complex 28 is quite effective. The nitrido species 29 and 30 are five-coordinate, square-pyramidal complexes; however, they are rather sluggish catalysts.…”

X-ray structure of [Re(NO)2.09Br1.91(PPh3)2] and DFT studies of [Re(NO)2Br2(PPh3)2]

“…Refinement of the structure in non-centrosymmetric space groups C2 and Cc did not change the disordered atom composition and the Flack parameter was equal to 0.5 in both cases; thus space group C2/c was selected as the correct one. The complex is isomorphous with [ReX 3 (NO)(PPh 3 ) 2 ] (X ¼ Cl and Br) [22,23], [ReOCl 3 (PPh 3 ) 2 ] [38] and several similar ruthenium nitrosyl compounds [39,40]. The packing of the two bulky triphenylphosphine ligands, which lie trans to each other, seems to govern the solid state structure.…”