Synthesis and Reactivity of Phosphinocarbyne Complexes

2016

Organometallics

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A range of chlorophosphinocarbyne complexes [W(CPClR)(CO) 2 (Tp*)] (R = Cl, Cy, Ph; Tp* = hydrotris-(3,5-dimethylpyrazol-1-yl)borate) has been prepared by reaction of chlorophosphines with the lithiocarbyne complex [W{ CLi(THF) n }(CO) 2 (Tp*)]. These complexes undergo nucleophilic substitution of chloride to enable the preparation of phosphinocarbynes bearing alkyl, aryl, alkynyl, aryloxy, and secondary phosphino substituents [W(CPRR′)(CO) 2 (Tp*)] (R = Ph, R′ = Me, Ph, CCPh, OPh, H; R = Cy, R′ = H). ■ INTRODUCTIONCarbynes L n MCR, as one of the simplest carbon-based ligands, and phosphines, as ubiquitous (spectator and noninnocent) ligands, both represent in their own way fundamental groups in organometallic chemistry. Despite dating back to Fischer's seminal report in 1973, 1 the appearance of carbyne complexes in the literature remains somewhat sporadic. A notable exception to this involves carbyne complexes serving as catalysts for alkyne metathesis, which continues to receive considerable attention. 2−8 Carbyne complexes bearing heteroatom carbyne substituents have been less studied, and in part this reflects limitations in synthetic methodologies that are typically distinct from classical Fischer or Schrock protocols. 9−16 We have enjoyed some success employing the "M-(CO) 2 (Tp*)" fragments (M = Mo, W; Tp* = 3,5-hydrotris-(dimethylpyrazolyl)borate)) for the construction of comparatively elaborate carbyne complexes, in particular those that bear heteroatomic carbyne subsitutents. 17−29 The combination of the bulky Tp* ligand (Tolman cone angle = 224°), 30 which affords kinetic stabilization, and the π-acidic CO coligands, which render the metal center relatively inert, allows modifications at the carbyne ligand to proceed, in many cases, without disruption of the MC linkage or M-(CO) 2 (Tp*) coordination sphere. In contrast to carbyne chemistry, phosphorus chemistry is very mature. Chlorophosphines are the quintessential building blocks for a myriad of phosphorus species due to the high reactivity of the P−Cl linkage and subsequent ease of nucleophilic substitution at this position.Combining these two principles we have considered the marriage of conventional organophosphorus chemistry with that of carbyne complexes. We have previously demonstrated that tertiary phosphinocarbyne complexes [M(CPPh 2 )-(CO) 2 (Tp*)] (M = W 2a, Mo 2b)) 21,29 and phosphonito carbynes [Mo{CP(O)(OEt) 2 }(CO) 2 (Tp*)] 21 are readily accessible from the bromocarbyne precursor [M(CBr)-(CO) 2 (Tp*)] (M = W 1a, Mo 1b) via lithium/halogen exchange with n BuLi and nucleophilic substitution of PClPh 2 or alternatively via palladium-catalyzed phosphination using PH-(O)(OEt) 2 , respectively. These complexes possess relatively inert phosphorus centers, undergoing conventional "phosphinetype" reactions with electrophiles, oxidants, and metal centers.In search of more versatile precursors, it has been found that the palladium-mediated protocol is also effective for the preparation of secondary phosphinocarbynes [W(CPHR)-(CO) 2 (Tp...

Section: Scheme 1 Phosphinocarbynes As Precursors To Phosphaisocyanimentioning

confidence: 99%

Section: Scheme 1 Phosphinocarbynes As Precursors To Phosphaisocyanimentioning

confidence: 99%

Section: ■ Conclusionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 98%

Section: ■ Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Chlorophosphino Carbyne Complexes of Tungsten

Colebatch

2016

Organometallics

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In Search of Fulminate Analogues: L_nM≡CP=NR

Frogley

Shang

et al. 2020

Chemistry A European J

The “CPNR” ligand may be viewed as being isolobal with fulminate, CNO; however, attempts to prepare a complex of such a ligand resulted instead in a range of novel imino and aminophosphinocarbyne complexes. Sequential treatment of [Mo(≡CBr)(CO)2(Tp*)] (Tp*=hydrotris(dimethylpyrazolyl)borate) with nBuLi and ClP=NMes* (Mes*=C6H2tBu3‐2,4,6) afforded mixtures of the complexes [Mo(≡CPnBuNHMes*)(CO)2(Tp*)] and traces of the bimetallic products [Mo2{μ2‐C2P2O(NHMes)2}(CO)4(Tp*)2] and [Mo2(μ2‐C2PNHMes)(CO)4(Tp*)2]. The reaction of [W(≡CBr)(CO)2(Tp*)] with nBuLi and ClP=NMes* afforded predominantly the mononuclear carbyne [W{≡CP(=NMes*)nBu2})(CO)2(Tp*)] and traces of the binuclear complex [W2(μ‐C2PNHMes)(CO)4(Tp*)2] which is also obtained when tBuLi is used. Although not isolable, the intended complexes [M(≡CPNMes*)(CO)2(Tp*)] could be generated in situ and spectroscopically characterized via the reactions of the stannyl carbynes [M(≡CSnnBu3)(CO)2(Tp*)] and ClP=NMes*. The preceding observations are mechanistically interpreted with reference to a computational interrogation of the model complex [Mo(≡CP=NCH3)(CO)2(Tp*)], the LUMO of which has considerable phosphorus character.

Pnictogen‐Functionalised C₁ Ligands: MC‐AR_n (n=0, 1, 2, 3)

Colebatch

Frogley

et al. 2021

Chemistry A European J

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The chemistryo ft ransitionm etal carbynes, L n M CR, has historically been dominated by speciesb earing hydrocarbyl or amino 'R' substituents, with other elements appearing only sporadically.I nr ecent years, carbynes and related 'C 1 's pecies bearing other main-group substituents, particularly heaviere lements of the p-block, have begun to emerge. This review details the chemistry of heavier pnicto-gen-functionalised C 1 ligands, MCAR n (A = P, As, Sb, Bi; n = 0-3), including their syntheses, properties andr eactivities,a nd how thesea re distinguished from more traditional carbyne complexes.R ecent developments in the closely related phospha-isonitrile L n M(CPR), cya-phosphide and cya-arside ligands,L n M(C A) (A = P, As), are also discussed.