New Iron(II)- and Gold(I)-Containing Metallocenes. X-ray Structure of a Three-Coordinate Gold(I) Ferrocenophane-Type Representative

Abstract

The metallophosphines l,l'-bis(diphenylphosphino)octamethylferrocene (dppomf) ( 5) and (l,T-octamethylferrocenediyljphenylphosphane (4) have been synthesized by reacting FeCla with lithium (diphenylphosphino)tetramethylcyclopentadienide and bis(tetramethylcyclopentadienyl)phenylphosphine dilithium salt, respectively. When 5 was reacted with ClAu(tht) (tht = tetrahydrothiophene) in a 1:2 ratio, 6 was obtained in which one AuCl unit is coordinated to each phosphine group. The proportion 1:1 led to the three-coordinate gold(I) monomer complex 7, of which the X-ray structure has been established. It crystallizes in space group P2\/c, monoclinic, with a = 23.153(4) Á, b = 9.070(4) Á, c = 20.414(3) Á, ß = 114.2(1)°, and Z = 4. The gold atom is trigonal planar, the Au-P and Au-Cl bond lengths are greater than those in linear P-Au-Cl complexes. The cyclopentadienyl rings are planar, parallel, and staggered by 17°, and the methyl substituents deviate slightly both sides from the plane. The pseudotriplets observed in 13C NMR for the cyclopentadienyl part are the result of long-range coupling with the two phosphorus atoms through gold. The stability of 7 in solution is shown by finding the same spectrum again after several hours. Electrochemistry showed the formation of Fe(III) derivatives of the metallophosphine gold(I) complexes, which can also be obtained by direct reaction of the precursors with electrochemically generated [Cp2Fe]+. The 197Au Mossbauer parameters for 6 and 8 are typical for linear twocoordination of gold(I), and the particularly small IS value for 7 can be explained by the strained P-Au-P angle which decreases the s-character of the P-Au bond. The reactivity of 6 and 7 was shown by the substitution of the chlorine atoms by the nucleophile CeFsaffording the fluorine-containing complexes 8 and 9, respectively. Compound 9 represents the first example of a P-Au(-P)-C tricoordinate gold(I). Complexes 5-8 have been tested in vitro against various human cancer cells. The cytotoxicity, although improved by the presence of gold, is not better than that of drugs already known.

Perfluoroarylgold complexes

“…For the isolation of perfluorophenylgold derivatives ligands with different donor atoms, such as sulfur [Fc(S 2 CNEt 2 ) 2 , Fc(SPh) 2 Tables 1 and 2 [151][152][153][154][155][156][157][158][159][160][161][162][163].…”

Bis(diphenylphosphino)-ferrocene or -dicarba-closo-dodecaborane as ligands in gold and silver chemistry

“…19,20 With the related diphosphine 1,1'-bis(diphenylphosphino) octamethylferrocene (dppomf), other similar dinuclear complexes, [(AuX) 2 [(dppomf)] (X = Cl, C 6 F 5 ), can be obtained. 21 Electrochemical studies show the formation of iron(III) derivatives of the metallophosphine gold(I) complexes, which can also be obtained by direct reaction of the precursors with electrochemically generated [FeCp 2 ] . 21 Substitution reactions from [(AuCl) 2 (13), is obtained from the reaction of [(AuCl) 2 (dppf)] and dppf, in a 1:1 molar ratio.…”

“…21 Electrochemical studies show the formation of iron(III) derivatives of the metallophosphine gold(I) complexes, which can also be obtained by direct reaction of the precursors with electrochemically generated [FeCp 2 ] . 21 Substitution reactions from [(AuCl) 2 (13), is obtained from the reaction of [(AuCl) 2 (dppf)] and dppf, in a 1:1 molar ratio. 25 Some interesting derivatives have been reported where [Au 2 (dppf)] 2 fragments coordinate around a central sulfur or selenium atom.…”

“…32 The reaction of the closo-diphosphine dppcc with [AuCl(AsPh 3 )] gives two very different complexes, depending on the molar ratio used. With an excess of phosphine (2:1 molar ratio), the four-coordinate [Au(dppnc)(dppcc)] (21), which contains the partially degraded dppnc phosphine, is obtained. However, when the molar ratio is 1:2, the tetranuclear cluster [Au 4 (dppnc) 2 (AsPh 3 ) 2 ] (22) is formed.…”

Electrochemistry and UV/visible spectroscopy of phosphino-substituted bis(η5-indenyl)iron(II) complexes

“…This reaction may be a dimerization, a reaction with adventitious water, or reaction with perchlorate electrolyte [9,10]. Other ferrocenes containing a phosphine directly attached to the ring generally show unusual electrochemistry also [4,11], with notable exceptions being (diphenylphosphino)ferrocene [11][12][13][14] [16]. Given the generally complicated electrochemistry of phosphine-substituted ferrocenes and the tendency of indenyl complexes to be more sensitive than their cyclopentadienyl analogues (due to their ability to undergo facile ring-slippage reactions), we expected the electrochemistry of the diindenyl analogue of dppf to be similarly complicated: at least reversible followed by a fast chemical reaction, if not irreversible-especially since a cationic oxidation product should be more susceptible to nucleophilic attack and subsequent decomposition processes via ring-slippage reactions.…”