Reductive Elimination at Pb(II) Center of an (Amino)plumbylene‐Substituted Phosphaketene: New Pathway for Phosphinidene Synthesis

Abstract

A stable (amino)plumbylene-substituted phosphaketene 3 was synthesized by the successive reactions of PbCl 2 with two anionic reagents (lithium amidophosphine and NaPCO). Of particular interest, the thermal evolution of 3, at 80 °C, leads to the transient formation of corresponding amino-and phosphanylidene-phosphaketenes (6 and 7), via a reductive elimination at the Pb II center forming new NÀ P and PÀ P bonds. Further evolution of 6 gives a new cyclic (amino)phosphanylidene phosphorane 4, which shows a unique reactivity as a phosphinidene. This result provides a new synthetic route to phosphinidenes, extending and facilitating further their access.

Photolysis of Phosphaketenyltetrylenes with a Carbazolyl Substituent

“…All 1 H NMR resonances are broadened which indicates hindered molecular motion. Thus, not reductive elimination of Pb 0 occurred as previously observed by Kato [27] …”

“…These coupling constants are considerably larger than observed for 1 J CP in phosphines (i. e. PMe 3 10.9 Hz), [38] but agrees well with the 1 J CP observed in other P=C double bond species such as NHC-phosphinidene adducts [39,40] or other phosphaketenes (i. e. HPCO). [41] The 31 P NMR data show that in 1E, the nucleus is less shielded than base-stabilised phosphaketenyltetrylenes, [24,25,27,32] but more shielded than in dicoordinated arylsilylamido-stabilised phosphaketenyl tetrylenes. In the IR spectrum, the v(C=O) mode was detected at 1915, 1897, and 1882 cm À 1 for 1Ge, 1Sn, and 1Pb.…”

“…Thus, not reductive elimination of Pb 0 occurred as previously observed by Kato. [27] The compound 3 also crystallised out of the reaction mixture and allowed the elucidation of its molecular structure (Figure 4). The central structural motif is a Pb 2 P 2 CO core, which has two dtbp Cbz substituents bonded to one P and one Pb atom and thus can be envisaged as comprising a [( dtbp Cbz)PPb] and a [( dtbp Cbz)PbPCO] moiety.…”

“…[21][22][23] Among the group 14 derivatives, there are base-stabilised (i. e. tricoordinated tetrylenes) and base-free examples with dicoordinated tetrylenes. The tricoordinated species were investigated by the groups of Driess (C), [24,25] Kato (D), [26,27] Goicoechea, [28] Zhao, [29] and Aldridge, [30] and gave interesting products after decarbonylation. There is less precedence for base-free phosphaketenyl tetrylenes.…”

Lewis Base Adducts of Phosphine-Stabilized Pb(II) Cations: Synthesis and Catalytic Hydroamination of Alkynes

“…The reaction of phosphine stabilized chloroplumbylene complex 1 with KB­(C 6 F 5 ) 4 or NaB­[3,5-(CF 3 ) 2 C 6 H 3 ] 4 (MBAr F 4 ) readily generates the Pb­(II) cation 2 as a complex with chloroplumbylene 1 via the coordination of the chlorine atom to the cationic Pb­(II) center (Scheme ). Even with an excess amount of borate salt (5 equiv), the free two-coordinate Pb­(II) cation cannot be obtained, probably due to its excessively high electrophilic character.…”