Synthesis and characterization of a ‘3+2’ {Re(V)O}3+ core complex carrying the ONS/PO donor atom set

(2-Hydroxy-phenyl-imido-κN)(methano-lato-κO)[2-(2-oxidobenzyl-ideneamino)phenolato-κO,N,O'](triphenyl-phosphine-κP)rhenium(V)

In the neutral title compound, [Re(C(6)H(5)NO)(C(13)H(9)NO(2))(CH(3)O)(C(18)H(15)P)], an 18-valence-electron complex, the Re(V) ion lies in an octa-hedral coordination geometry with the tridentate dianionic Schiff base 2-(2-oxidobenzyl-idene-amino)phenolate ligand occupying three equatorial coordination sites, and with the triphenyl-phosphine ligand situated trans to the imine N atom. The Re(V) coordination is completed with a methano-late ligand and a 2-hydroxy-phenyl-imido(2-) ligand. There are two molecules in the asymmetric unit. The crystal structure involves O-H⋯O and C-H⋯O hydrogen bonds. One N and one C atom are disordered over two positions; the site occupancy factors are ca 0.7 and 0.3.

Synthesis and Characterization of Novel “3 + 2” Oxorhenium Complexes, ReO[SNO][NN]

The present paper deals with the synthesis and structural characterization of novel neutral oxorhenium(V) complexes of the general formula ReO[SNO][NN]. The simultaneous action of the tridentate SNO ligand, N-(2-mercaptoacetyl)glycine (1), and the bidentate NN ligand, N-phenylpyridine-2-aldimine (2), on ReOCl3(PPh3)2 leads to the formation of two isomers 4a and 4b of the general formula ReO[SNO][NN], as a result of the different orientations of the NN ligand. In both cases, the SNO donor atoms of the tridentate ligand occupy the three positions in the equatorial plane of the distorted octahedron, whereas the oxo group is always directed toward one of the apical positions. In the first isomer, 4a, the imino nitrogen of the NN ligand occupies the fourth equatorial position and the pyridine type nitrogen is directed trans to the oxo group, while in the second isomer, 4b, the imino nitrogen of the NN ligand occupies the apical position trans to the oxo group and the pyridine type nitrogen completes the equatorial plane of the distorted octahedron. The [SNO][NN] mixed-ligand system was applied in the synthesis of the oxorhenium complex 5 in which the 1-(2-methoxyphenyl)piperazine moiety, a fragment of the true 5-HT1A antagonist WAY 100635, has been incorporated in the NN bidentate ligand (NN is N-{3-[4-(2-methoxyphenyl)piperazin-1-yl]propyl}pyridine-2-aldimine). In this case, high-performance liquid chromatography and NMR showed the existence of one isomer, 5, in which the pyridine nitrogen is trans to the oxo core, as demonstrated by crystal structure analysis.

Rhenium(V) Complexes with Thiolato and Dithiolato Ligands: Synthesis, Structures, and Monomerization Reactions

The new compound {(PhS)(2)ReO(mu-SPh)}(2), 1, was synthesized from Re(2)O(7) and PhSH and then used as the synthon for a number of hitherto unknown oxorhenium(V) compounds. Reactions between dithiols and 1 (2:1 ratio) afford {PhSReO(dt)}(2), where the dithiols, dtH(2), are 1,2-ethanedithiol (edtH(2)), 1,3-propanedithiol (pdtH(2)), 1,3-butanedithiol (pdtMeH(2)), 1,2-benzenedithiol (bdtH(2)), 2-(mercaptomethyl)thiophenol (mtpH(2)), and 2-mercaptoethyl sulfide (mesH(2)). Similar reactions carried out with a 3:1 ratio of dtH(2) to 1 afford [(ReO)(2)(dt)(3)], dt = edt, pdt. When NEt(3) was introduced prior to the 3:1 reaction between edtH(2) and 1, a compound containing an anionic complex was isolated, [PPh(4)][ReO(edt)(2)]. The new compounds were characterized analytically, spectroscopically, and crystallographically. The Re-O groups in two of the compounds, 1 and {ReO(mu-SPh)(bdt)}(2), exist in rare anti orientations; the others adopt the more familiar syn geometry, as discussed. Selected monomerization reactions of {PhSReO(dt)}(2) were also carried out: {PhSReO(dt)}(2) + 2L = 2[PhSReO(dt)L]. The rate for L = 4-phenylpyridine is given by v = {k(a)[L] + k(b)[L](2)} x [{PhSReO(dt)}(2)], as it is for the reactions of {MeReO(dt)}(2); for all of these compounds, the reaction proceeds nearly entirely by the third-order pathway. Values of k(b)/L(2) mol(-2) s(-1) at 25.0 degrees C are 5.8 x 10(2) (mtp), 2.97 x 10(3) (pdt), 4.62 x 10(5) (edt), and 3.87 x 10(5) (bdt). The rate law for the reactions of {PhSReO(dt)}(2) with L = PAr(3) is v = k(a)[L]/{1 + kappa[L]} x [{PhSReO(dt)}(2)]. For PPh(3), values at 25.0 degrees C of k(a)/L mol(-1) s(-1) (kappa/L mol(-1)) for {PhSReO(dt)}(2) are 9.64 x 10(-2) (1.87) for mtp, 3.43 x 10(-2) (0.492) for pdt, 1.91 (1.42) for edt, 1.84 x 10(-2) (0.82) for bdt, and 1.14 x 10(3) (10.6) for 1. Mechanisms are proposed that are consistent with the data obtained and with earlier work.