Gold(I) and Silver(I) Complexes of Diphosphacyclobutadiene Cobaltate Sandwich Anions

Abstract

The synthesis and structural characterization of the first coordination compounds of bis(diphosphacyclobutadiene) cobaltate anions [M(P(2)(2)R(2))(2)](-) is described. Reactions of the new potassium salts [K(thf)(3){Co(η(4)-P(2)C(2)tPent(2))(2)}] (1) and [K(thf)(4){Co(η(4)-P(2)C(2)Ad(2))(2)}] (2) with [AuCl(tht)] (tht = tetrahydrothiophene), [AuCl(PPh(3))] and Ag[SbF(6)] afforded the complexes [Au{Co(P(2)C(2)tPent(2))(2)}(PMe(3))(2)] (3), [Au{Co(P(2)C(2)Ad(2))(2)}](x) (4), [Ag{Co(P(2)C(2)Ad(2))(2)}](x) (5), [Au(PMe(3))(4)][Au{Co(P(2)C(2)Ad(2))(2)}(2)] (6), [K([18]crown-6)(thf)(2)][Au{Co(P(2)C(2)Ad(2))(2)}(2)] (7), and [K([18]crown-6)(thf)(2)][M{Co(P(2)C(2)Ad(2))(2)}(2)] (8: M = Au 9: M = Ag) in moderate yields. The molecular structures of 2 and 3, and 6-9 were elucidated by X-ray crystallography. Complexes 4-9 were thoroughly characterized by (31)P and (13)C solid state NMR spectroscopy. The complexes [Au{Co(P(2)C(2)Ad(2))(2)}](x) (4) and [Ag{Co(P(2)C(2)Ad(2))(2)}](x) (5) exist as coordination polymers in the solid state. The linking mode between the monomeric units in the polymers is deduced. The soluble complexes 1-3, 6, and 7 were studied by multinuclear (1)H-, (31)P{(1)H}-, and (13)C{(1)H} NMR spectroscopy in solution. Variable temperature NMR measurements of 3 and 6 in deuterated THF reveal the formation of equilibria between the ionic species [Au(PMe(3))(4)](+), [Au(PMe(3))(2)](+), [Co(P(2)C(2)R(2))(2)](-), and [Au{Co(P(2)C(2)R(2))(2)}(2)](-) (R = tPent and Ad).

Solid state NMR studies and chemical shift calculations of a gold(I) complex with a diphosphacyclobutadiene cobaltate sandwich anion

“…Thus, this experiment confirms that the signal at −18.2 ppm must be assigned to P2. The results obtained on this material are completely analogous to those reported on compound 1 in reference [5], where the same assignment strategy was used. (No two-dimensional NMR work was possible on compound 1, owing to very fast spin-spin relaxation).…”

“…Table 3 indicates that similarly good agreement between theory and experiment is observed for the negatively charged anion of compound 1, where the simpler basis set TZP, in combination with the BP86 functional had to be used for reasons of limited computational capacity. All of these results now indicate unambiguously that the tentative 31 P NMR peak assignment made for compounds 1 and 2 in reference [5] and shown in Fig. 2 needs correction.…”

“…The synthesis, crystal structure and basic characterization of compounds 1-3 has been reported in [5]. Fig.…”

“…metal complexes where one or several carbon atoms in an organic ligand have been substituted by phosphorus, have been attracting considerable attention over the years [1][2][3][4]. Recently, the synthesis and structural characterization of the first coordination compounds of bis(diphosphacyclobutadiene) cobaltate anions [Co(P 2 C 2 R 2 ) 2 ] − has been described [5]. Specifically, [Au(PMe 3 ) 4 ][Au{Co(P 2 C 2 Ad 2 ) 2 } 2 ] (1), and [K(18-crown-6)(thf) 2 ][Au{Co(P 2 C 2 Ad 2 ) 2 } 2 ] (Ad¼adamantyl) (2) were characterized in detail by single-crystal X-ray crystallography and solid state NMR spectroscopy.…”

“…summarizes the one-dimensional 31 P MAS-NMR spectra of compounds 1 and 2[5]. Based on its spectral proximity with the [Au(PMe 3 ) 4 ] + resonance at −35.4 ppm we had previously assigned the resonance at −43.4 ppm to the Au(I) bonded phosphorus atom.…”