Getting a Clue to the Hydrolytic Activation of White Phosphorus: The Generation and Stabilization of P(OH)2PHPHPH(OH) at Ruthenium Centers

Functionalization of Tetraphosphido Ligands by Heterocumulenes

Although numerous polyphosphido complexes have been accessed through the transition-metal-mediated activation and functionalization of white phosphorus (P4), the selective functionalization of the resulting polyphosphorus ligands in these compounds remains underdeveloped. In this study, we explore the reactions between cyclotetraphosphido cobalt complexes and heterocumulenes, leading to functionalized P4 ligands. Specifically, the reaction of carbon disulfide (CS2) with [K(18c-6)][(Ar*BIAN)Co(η4-P4)] ([K(18c-6)]1, 18c-6 = [18]crown-6) affords the adduct [K(18c-6)][(Ar*BIAN)Co(η3:η1-P4CS2)] ([K(18c-6)]3), in which CS2 is attached to a single phosphorus atom (Ar* = 2,6-dibenzhydryl-4-isopropylphenyl, BIAN = 1,2-bis(arylimino)acenaphthene diimine). In contrast, the insertion of bis(trimethylsilyl)sulfur diimide S(NSiMe3)2 into a P-P bond of [K(18c-6)]1 yields [K(18c-6)][(Ar*BIAN)Co(η3:η1-P4SN2(SiMe3)2)] (K(18c-6)]4). This salt further reacts with Me3SiCl to form [(Ar*BIAN)Co(η3:η1-P4SN2(SiMe3)3] (5), featuring a rare azatetraphosphole ligand. Moreover, treatment of the previously reported complex [(Ar*BIAN)Co(η3:η1-P4C(O)tBu)] (2) with isothiocyanates results in P-C bond insertion, yielding [(Ar*BIAN)Co(η3:η1-P4C(S)N(R)C(O)tBu)] (6a,b; R = Cy, Ph).

Cobalt-Mediated [3+1] Fragmentation of White Phosphorus: Access to Acylcyanophosphanides

Despite the accessibility of numerous transition metal polyphosphido complexes through transition-metal-mediated activation of white phosphorus, the targeted functionalization of Pn ligands to obtain functional monophosphorus species remains challenging. In this study, we introduce a new [3+1] fragmentation procedure for cyclo-P4 ligands, leading to the discovery of acylcyanophosphanides and -phosphines. Treatment of the complex [K(18c-6)][(Ar*BIAN)Co(η4 -P4 )] ([K(18c-6)]3, 18c-6=[18]crown-6, Ar*=2,6-dibenzhydryl-4-isopropylphenyl, BIAN=1,2-bis(arylimino)acenaphthene diimine) with acyl chlorides results in the formation of acylated tetraphosphido complexes [(Ar*BIAN)Co(η4 -P4 C(O)R)] (R=tBu, Cy, 1-Ad, Ph; 4 a-d). Subsequent reactions of 4 a-d with cyanide salts yield acylated cyanophosphanides [RC(O)PCN]- (9 a-d- ) and the cyclo-P3 cobaltate anion [(Ar*BIAN)Co(η3 -P3 )(CN)]- (8- ). Further reactions of 4 a-d with trimethylsilyl cyanide (Me3 SiCN) and isocyanides provide insight into a plausible mechanism of this [3+1] fragmentation reaction, as these reagents partially displace the P4 C(O)R ligand from the cobalt center. Several potential intermediates of the [3+1] fragmentation were characterized. Additionally, the introduction of a second acyl substituent was achieved by treating [K(18c-6)]9b with CyC(O)Cl, resulting in the first bis(acyl)monocyanophosphine (CyC(O))2 PCN (10).

Transition-Metal-Mediated Functionalization of White Phosphorus

Recently there has been great interest in the reactivity of transition-metal (TM) centers towards white phosphorus (P4 ). This has ultimately been motivated by a desire to find TM-mediated alternatives to the current industrial routes used to transform P4 into myriad useful P-containing products, which are typically indirect, wasteful, and highly hazardous. Such a TM-mediated process can be divided into two steps: activation of P4 to generate a polyphosphorus complex TM-Pn , and subsequent functionalization of this complex to release the desired phosphorus-containing product. The former step has by now become well established, allowing the isolation of many different TM-Pn products. In contrast, productive functionalization of these complexes has proven extremely challenging and has been achieved only in a relative handful of cases. In this review we provide a comprehensive summary of successful TM-Pn functionalization reactions, where TM-Pn must be accessible by reaction of a TM precursor with P4 . We hope that this will provide a useful resource for continuing efforts that are working towards this highly challenging goal of modern synthetic chemistry.

Reactivity of Phosphanylphosphinidene Complex of Tungsten(VI) toward Phosphines: A New Method of Synthesis of catena-Polyphosphorus Ligands

The reactivity of an anionic phosphanylphosphinidene complex of tungsten(VI), [(2,6-i-Pr2C6H3N)2(Cl)W(η(2)-t-Bu2P═P)]Li·3DME toward PMe3, halogenophosphines, and iodine was investigated. Reaction of the starting complex with Me3P led to formation of a new neutral phosphanylphosphinidene complex, [(2,6-i-Pr2C6H3N)2(Me3P)W(η(2)-t-Bu2P═P)]. Reactions with halogenophosphines yielded new catena-phosphorus complexes. From reaction with Ph2PCl and Ph2PBr, a complex with an anionic triphosphorus ligand t-Bu2P-P((-))-PPh2 was isolated. The main product of reaction with PhPCl2 was a tungsten(VI) complex with a pentaphosphorus ligand, t-Bu2P-P((-))-P(Ph)-P((-))-P-t-Bu2. Iodine reacted with the starting complex as an electrophile under splitting of the P-P bond in the t-Bu2P═P unit to yield [(1,2-η-t-Bu2P-P-P-t-Bu2)W(2,6-i-Pr2C6H3N)2Cl], t-Bu2PI, and phosphorus polymers. The molecular structures of the isolated products in the solid state and in solution were established by single crystal X-ray diffraction and NMR spectroscopy.

Iodine activation of coordinated white phosphorus: formation and transformation of 1,3-dihydride-2-iodidecyclotetraphosphane

Double stabilization: Previously unknown polyphosphorus compounds are obtained by activation of white phosphorus (P(4)) coordinated between two CpRu(PPh(3))(2) moieties with iodine, and subsequent hydrolysis. The polyphosphorus compounds (P(4) H(2) I, P(4) H(2), P(3) H(5); see scheme, Cp=cyclopentadienyl) are all stabilized by coordination to two ruthenium centers.