Unusual Phosphorus−Phosphorus Double Bond Contraction upon Mono- and Di-auration of a Diphosphene

Abstract

The diphosphene Mes*P=Mes* (Mes* = 2,4,6-tri-tert-butylphenyl; 1) reacted with 1 or 2 equiv of Au(tht)Cl (tht = tetrahydrothiophene) to produce the stable monoaurated adduct Mes*{AuCl}P=PMes* (2) or diaurated adduct Mes*{AuCl}P=P{AuCl}Mes* (3) respectively. The products were characterized by X-ray crystallography, UV-visible, IR, Raman, and multinuclear NMR spectroscopies, as well as by density functional theory calculations. The crystallographic and Raman spectroscopic data provide physical evidence that the P=P bond grows shorter and increases in strength upon auration; these observations are further examined by DFT calculations for a series of model compounds CH(3){AuCl}(n)P=P{AuCl}(n')CH(3) 1'-3' (n, n' = 0 or 1). Compounds 1-3 represent a rare series of crystallographically characterized diphosphenes bearing zero, one, or two AuCl units on each phosphorus atom, allowing for a systematic analysis of the impact of Lewis acids on the phosphorus-phosphorus double bond.

Platinum(II) complexes of some unsymmetrical diphosphenes

“…For the new diphosphene 7, the 31 P peaks may thus be assigned with confidence. Similar computations were also carried out for known diphosphenes coordinated to cationic methyl group [25] or metals in an η 1 fashion [7,9,26] as listed in Table 2, and Figure 3 demonstrates the good agreement between observed and computed (GIAO) 31 P NMR data. Table 4.…”

“…[5,6] Occasionally it is possible to coordinate a metal to each of the phosphorus atoms in an η 1 mode, as in the mono-and di-AuCl complexes of Ar*P=PAr* 5 (Ar* = 2,4,6-t Bu 3 C 6 H 2 ). [7] For an unsymmetrical diphosphene R 1 P=PR 2 there is the additional possibility of η 1 coordination by either of the inequivalent phosphorus atoms. Cowley et al showed that the diphosphene 2,4,6-t Bu 3 C 6 H 2 P(1)=P(2)CH(SiMe 3 ) 2 reacted with Fe 2 (CO) 9 to afford a single product in 63% yield, with Fe(CO) 4 coordinated to P(2).…”

Constrained Digold(I) Diaryls: Syntheses, Crystal Structures, and Photophysics

“…Previous authors have suggested that Au···O distances of less than 3.5 may have a small influence on the observed solid-state conformation of similar diphosphine gold complexes [LA C H T U N G T R E N N U N G (AuCl) 2 ] (L= DPEphos, DBFphos, Xantphos). [31] However, other reports indicate much shorter Au···O distances are possible (as short as 2.922(1) in one report of a mononuclear gold(I) chloride complex [22] and 2.66 in a tBuXantphos-chelated complex), [30] suggesting that the Au···O distances observed here minimally influence the observed conformations. A complete list of geometric parameters of crystallographically characterized products is included as Table 6.…”

“…This distortion is measured by a parameter we have reported for similar gold-diphosphine complexes, the torsion angle P1-C ipso1 -C ipso2 -P2 (f 1 ). [30] Scheme 2 illustrates this angle (perspective down the C ipso1 À C ipso2 axis). The magnitude of this torsion angle is normally much greater for DPEphos derivatives relative to their closed-ring derivatives (e.g., Xantphos, tBuXantphos, DBFphos).…”

Anorganische Chemie 2009

“…Zwei phosphorbasierte Beispiele sind ebenfalls erwähnenswert: Die Stabilisierung des intermediären Li‐Cl‐Phosphenoids RP(Li)Cl‐(12‐Krone‐4) (R = CH(SiMe3)2, C5Me5) durch Komplexierung mit W(CO)562) und die ungewöhnliche P‐P‐Doppelbindungsverkürzung in Mes*‐P=P‐Mes* (Mes* = 2,4,6‐tri‐tBu‐C6H2) als Folge von Mono‐ oder Di‐Komplexierung mit AuCl 1_63…”