The Elusive Structures of Pentakis[(triphenylphosphine)gold]ammonium(2+) Bis[tetrafluoroborate(1−)]

Abstract

[Pentakis[(triphenylphosphine)gold(I)]ammonium(2+)] bis[(tetrafluoroborate)(1-)] was prepared from [tetrakis[(triphenylphosphine)gold(I)]-ammonium(1+)] [tetrafluoroborate(1-)] and [(triphenylphosphine)gold(I)] tetrafluoroborate in hexamethyl phosphoric triamide and tetrahydrofuran at 20 degrees C in 53% yield and crystallized from dichloromethane as the new solvate [[(Ph3P)Au]5N]3 [BF4]6 [CH2Cl2]4. The crystal structure of this product has been determined by single-crystal X-ray methods [monoclinic, P2(1/n), a = 34.200(3), b = 15.285(1), c = 53.127(3) A, beta = 107.262(2) degrees, V = 26521(3) A3, Z = 12, at 153 K]. The lattice contains three independent trinuclear dications that have no crystallographically imposed symmetry and are mutually similar in their molecular structure. The geometry of the [Au5N] core with pentacoordinate nitrogen atoms is intermediate between trigonal-bipyramidal and square pyramidal with severe distortions to minimize the Au-Au distances along some of the edges of the polyhedra. The three structures are thus different from that found previously in the tetrahydrofuran solvate [[(Ph3P)-Au]5N](BF4)2(C4H8O)2, where the geometry of the same trinuclear dication is closer to the trigonal-bipyramidal reference model. The new results are discussed in the light of the structures of tetra(gold)ammonium cations in salts of the type [[(Ph3P)Au]4N]+X- and of related tetra-, penta-, and hexacoordinate poly(gold)phosphonium, -arsonium, -sulfonium, and -selenonium cations.

Excimer and Exciplex Formation in Gold(I) Complexes Preconditioned by Aurophilic Interactions

“…In all cases, gold atoms are drawn together to sub‐van der Waals distances whenever this approach is allowed by the steric properties of the system. This attraction also leads to the unforced, counterintuitive gathering of complex gold(I) units [(L)Au] + at a given main‐group‐element or transition‐metal coordination center E in cations {E[Au(L)] n } m + …”

“…This attraction also leads to the unforced, counterintuitive gathering of complex gold(I) units [(L)Au] + at agiven maingroup-element or transition-metal coordination center Ei n cations {E[Au(L)] n } m+ . [71][72][73][74][75] As afirst criterion for further characterization, molecular and crystal structures were analyzed in order to determine the relevant range of Au-Aud istances.S urprisingly,f or gold(I) complexes the lower end of about 2.75 is already shorter than the sum of two metallic radii (2.88 in fcc gold metal) and not much larger than the distances found in diamagnetic dinuclear complexes of gold(0) (5d 10 6s 1 )a nd gold(II) (5d 9 ), which both feature acovalent AuÀAu bond (2.47-2.61 ;see above). At the upper end, significant attraction is still observed (and calculated) near 3.50 ,w hich is close to the sum of two van der Waals radii of gold(I) (ca.…”

Excimer‐ und Exciplex‐Bildung in durch aurophile Wechselwirkungen präkonditionierten Gold(I)‐ Komplexen

“…In allen Fällen werden die Goldatome auf Sub‐van‐der‐Waals‐Abstände aneinander geführt, sobald die sterischen Voraussetzungen des Systems eine derartige Annäherung erlauben. Diese Anziehung führt in Kationen des Typs {E[Au(L)] n } m + auch zur spontanen, anti‐intuitiven Anhäufung komplexer Gold(I)‐Einheiten [(L)Au] + an einem gegebenen Hauptgruppenelement‐ oder Übergangsmetall‐Koordinationszentrum E …”

Gold Clustering at Dimethylsulfoximine Me2S(O)NH

“…Clustering at nitrogen [6 ] is particularly com mon and was found to occur readily at ammonia [7], hydrazine [8 ], hydroxylamine [9], primary and secondary amines and amides [1 0 ], and a variety of imines [11]. This chemistry not only includes standard aldimines and ketimines (Schiff bases RR'C=NH), but also carbodiimines [12] and phos phinimines R 3P=NH [13].…”