Transition-Metal-like Behavior of Main Group Elements: Ligand Exchange at a Phosphinidene

Abstract

(Phosphino)phosphaketenes (>P-P═C═O) behave as (phosphino)phosphinidene-carbonyl adducts (>P-P←:C═O). CO scrambling was observed using C labeled CO, and exchange reactions with phosphines afford the corresponding (phosphino)phosphinidene-phosphine adducts (>P-P←:PR). The latter react with isonitriles and singlet carbenes giving (phosphino)phosphinidene-isonitrile (>P-P←:CNR) and -carbene adducts (>P-P←:C<). Based on experimental results and DFT calculations, it is shown that these "ligand" exchange reactions occur via an associative mechanism as classically observed with transition metal complexes.

(Phosphanyl)phosphaketenes as building blocks for novel phosphorus heterocycles

“…In contrast to our recent reported CO substitution approach, 12 this work demonstrates the feasibility of nucleophiles to add to carbon on the phosphaketene moiety. The endocyclic P center can either activate the phosphaketene by forming highly reactive diphosphirenium species or engage in ring closing reactions.…”

“…As isonitriles and carbon monoxide are isoelectronic, we were interested in the thermal substitution of the CO in phosphaketene 1 Dipp by an isonitrile, using our recently reported ligand exchange strategy. 12 Surprisingly, the isonitrile does not add at the phosphorus center of PCO to displace CO, as previously observed with phosphines, but attacks at the carbon. 25 This is followed by a cyclization involving the endocyclic P and the resulting heterocycle 8 was isolated in 85% yield ( δ 31 P 148.0 and 88.3 ppm, J = 370 Hz) (Scheme 5, Fig.…”

“…We have already reported that elimination of CO occurred under irradiation of 1 Ar** , affording the corresponding room temperature stable phosphinidene 2 Ar** , 10 a while addition of phosphines to 1 Ar** and 1 Dipp leads to adducts 3 . 12 In both of these reactions, the phosphaketene group acts as a phosphinidene-carbonyl adduct. This behavior is reminiscent of the chemistry of transition metal carbonyl complexes, and it is noteworthy that before our work the chemistry of main group carbonyl compounds 13 was essentially limited to boranes, 14 polyboranes 15 and carbenes.…”

The Chemistry of the 2‐Phosphaethynolate Anion

“…[48,49] Theu se of phosphaethynolate as source of P À has also been observed in the reaction between an unsaturated three-membered silicon ring (a cyclotrisilene) and Na(OCP) (Scheme 7). [48,49] Theu se of phosphaethynolate as source of P À has also been observed in the reaction between an unsaturated three-membered silicon ring (a cyclotrisilene) and Na(OCP) (Scheme 7).…”

“…[66] Formally this reaction, which proceeds under loss of CO, can be viewed as a[3+ +1] cycloaddition of the P À anion to the P=C=Ounit. [48,49] [66] Note that this reaction does not proceed under substitution of CO by the isonitrile to give [P]ÀP=C= NR as observed with the bulky derivative with R = Ar**.…”