Coordination of a Di-<i>tert</i>-butylphosphidoboratabenzene Ligand to Electronically Unsaturated Group 10 Transition Metals

Macha, Bret B.; Boudreau, Josée; Maron, Laurent; Maris, Thierry; Fontaine, Frédéric‐Georges

doi:10.1021/om300668u

Cited by 26 publications

(13 citation statements)

References 65 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Conversion to this species was complete within 24 hours. This type of reactivity has been seen previously between platinum complexes of 1,5-hexadiene and secondary amines, [114][115][116] forming σ:η 2 -bound ammonium ions; and between platinum complexes of 1,5-cyclooctadiene and tertiary phosphines, [117][118][119][120] forming σ:η 2 -bound phosphonium ions. Unfortunately, the NMR data given for these complexes is sparse; however, when 3 J PtP coupling was reported it is in the range 156-223 Hz, similar to the 355 Hz coupling for complex 22.…”

supporting

confidence: 75%

Hybrid P,E Ligands: Synthesis, Coordination Chemistry and Catalysis

Allan¹

View full text Add to dashboard Cite

<p>This thesis provides an account of research into a family of novel hybrid P,E ligands containing an o-xylene backbone. A methodology for the synthesis of these ligands has been developed, and their coordination behaviour with platinum(II) and platinum(0) precursors has been explored, with particular focus on a phosphinethioether (P,S) ligand of this type. The coordination modes of this P,S ligand with palladium precursors have also been investigated, and the utility of the ligand in a palladium and copper co-catalysed Sonogashira carbon-carbon bond-forming reaction has been evaluated. A range of hybrid P,E ligands of the type o-C₆H₄(CH₂PBut₂)(CH₂E) (E = PR₂, SR, S(O)But, NR₂, SiPh₂H) have been synthesised in two or three steps from the novel substrate, o-C₆H₄(CH₂PBut₂(BH₃)}(CH₂Cl). The initial step involved treatment of the substrate with the appropriate nucleophilic reagent, or preparation of a Grignard reagent from o-C₆H₄{CH₂PBut₂(BH₃)}(CH₂Cl) and reaction with the appropriate electrophile. In most cases, this versatile strategy produced air-stable crystalline ligand precursors. Phosphine deprotection was achieved via one of three methods, dependent upon the properties of the second functional group. The reactivity of three of these ligands — o-C₆H₄{CH₂PBut₂)(CH₂SBut) (14a), o-C₆H₄{CH₂PBut₂){CH₂S(O)But} (16) and o-C₆H₄(CH₂PBut₂)(CH₂NMe₂) (18a) — with Pt(II) and Pt(0) precursor complexes has been investigated. Chelated [PtCl₂(P,E)] complexes were synthesised with P,S ligand 14a and P,N ligand 18a, but attempts to produce the equivalent species with P,S=O ligand 16 were unsuccessful. The X-ray crystal structure of [PtCl₂(P,S)] complex 21 displayed an unexpectedly small ligand bite angle of 86.1°. A series of platinum(II) hydride complexes of the types [PtHL(P,S)₂] and [PtHL(P,S)₂]CH(SO₂CF₃)₂ (L = Cl¯, H¯, NCMe, −CH₂SBut , CO, pta) have been synthesised, where ligand 14a binds in a monodentate fashion through the phosphorus donor atom. This work has demonstrated the hemilability of ligand 14a, via the facile and reversible conversion between [PtH(κ¹P-14a)(κ²P,S-14a)]CH(SO₂CF₃)₂ (26) and [PtH(NCMe)(κ¹P-14a)₂]CH(SO₂CF₃)₂ (28). The X-ray crystal structure of [PtH₂(P,S)₂] complex 25 was used to calculate a cone angle of 180° for the phosphine moiety in ligand 14a. Reaction of P,S ligand 14a and P,S=O ligand 16 with [Pt(alkene)₃] complexes (alkene = ethene, norbornene) gave the chelated [Pt(alkene)(P,E)] complexes 32–35; however, under similar conditions a [Pt(norbornene)(P,N)] complex did not form. A large ligand bite angle of 106.6° was observed in the X-ray crystal structure of [Pt(norbornene)(P,S)] complex 34. Reaction of two equivalents of each of the P,E ligands with [Pt(norbornene)₃] gave the corresponding 14-electron linear complexes [Pt(P,E)₂] (36–38) with the ligands coordinated through the phosphorus donor atoms only. The reactivity of [Pt(norbornene)(P,S)] complex 34 and [Pt(P,S)₂] complex 36 has been investigated, resulting in the complexes [PtH{CH(SO₂CF₃)₂}(P,S)] (39), [Pt(norbornyl)(P,S)] (40), [Pt(ethyne)(P,S)] (41) and [Pt(O₂)(P,S)₂] (42). The reactivity of P,S ligand 14a was investigated with Pd(II) and Pd(0) precursors, resulting in the identification of five coordination modes of this ligand. Monodentate binding was observed in [Pd(P,S)₂] complex 44, and chelation in the [Pd(alkene)(P,S)] complexes 47 (alkene = norbornene) and 48 (alkene = dba). Reaction of ligand 14a with [PdCl₂(NCBut)₂] at raised temperature resulted in S−C bond cleavage and the formation of palladium dimer 43 with bidentate coordination of the ligand through phosphine and bridging thiolate moieties. Reaction of ligand 14a with [Pd(OAc)₂] resulted in C−H activation of the aryl backbone and formation of [Pd(μ-OAc)(P,C)]₂ dimer 46. In the presence of excess [Pd(OAc)₂], palladium hexamer 45 was formed, with a combination of P,C palladacycle and monodentate thioether binding resulting in bridging P,C,S coordination of ligand 14a. The Sonogashira cross-coupling of 4-bromoanisole and phenylethyne was performed with 3 mol% of a pre-catalyst mixture containing P,S ligand 14a, [Pd(OAc)₂] and CuI, resulting in quantitative conversion to 4-(phenylethynyl)anisole in four hours. Two enyne by-products were also identified from the reaction. Variations to the pre-catalyst mixture and catalyst loading indicated there was a significant ligand dependence on the yield and selectivity of the reactions. Mercury drop tests and dynamic light scattering experiments confirmed the presence of palladium nanoparticles in the reaction solution; however, the active catalytic species in these reactions has not been identified.</p>

show abstract

supporting

confidence: 75%

Hybrid P,E Ligands: Synthesis, Coordination Chemistry and Catalysis

Allan¹

View full text Add to dashboard Cite

show abstract

“…In 2012, Fontaine and co-workers reported isolation of di-tert-butylphosphidoboratabenzene ([DTBB] -). 119 Reaction of 183 with t Bu 2 PCl afforded the adduct 246, which was reduced by liquefied potassium in benzene at 65 °C, resulting in the formation of the targeted compound 247 which exhibits limited solubility in the solution (Scheme 70). To increase the solubility, 18-crown-6 was added and compound 248 was obtained.…”

Section: Scheme 69 Synthesis Of Boratabenzene-phosphole Adductsmentioning

confidence: 99%

Construction of Boron-Containing Aromatic Heterocycles

Kinjo

2017

Synthesis

113

View full text Add to dashboard Cite

Boron-containing aromatic systems exhibit unique electronic properties and reactivities that have been extensively studied for a long time. This review highlights the recent developments in the synthesis of aromatic boron-containing heterocycles. The organization of the contents is based on the sizes of rings and the heteroatoms other than boron. Early work in the field is briefly introduced, but the main focus is on recent reports published during the period of 2008 through 2016.1 Introduction2 Five-Membered Rings2.1 Borole Derivatives2.2 B,N-Heterocycles2.3 B,O-Heterocycles3 Six-Membered Rings3.1 Borabenzene Derivatives3.2 Boratabenzene Derivatives3.3 1,4-Diborabenzene3.4 B,N-Heterocycles3.5 B,E-Heterocycles (E = O, S, P, Te)4 Three-Membered Rings4.1 Borirenes4.2 Azadiboriridines4.3 Triboracyclopropenyl Dianion5 Four-Membered Rings5.1 bicyclo-Tetraborane(4)5.2 1,3-Diborete5.3 B,E-Heterocycles (E = N, P, As, Sb, Bi, O, S, Se)6 Seven-Membered Rings (Borepines)7 Conclusion and Perspective

show abstract

“…In the latter case, the boron atom tends to be farther from the metal centre than the carbon atoms of the ring. It has been observed in some instances that the ring system can interact in an allylic‐like coordination; notably in a recent example reported by our research group of a platinum(II) di‐ tert ‐butylphosphido‐boratabenzene [Pt(DTBB) 2 ] species having a P–B–C interaction with the platinum centre (Figure 2, III ) 9. To the best of our knowledge, only two examples of an interaction between a boratabenzene ligand and a transition metal do not involve the π system of the heterocyclic ring.…”

Section: Introductionmentioning

confidence: 98%

Generation of Group VI Piano‐Stool and Triple‐Decker Complexes from [(IMes)₂PtH(Cl‐boratabenzene)] Species

2014

View full text Add to dashboard Cite

Species [(IMes)2Pt(H)(1‐Cl‐2‐SiMe3–BC5H4)] (1) was used as the source of the Cl‐boratabenzene anion for coordination to group VI transition metals, resulting in the formation of piano‐stool complexes [(η6‐1‐Cl‐2‐SiMe3–BC5H4)M(CO)3]– [M = Cr (2), Mo (4), W (5)] and a homodimetallic triple‐decker complex [(CO)3Cr(η6‐1‐Cl‐2‐SiMe3–BC5H4)Cr(CO)3]– (3). All species were spectroscopically characterized and the first X‐ray structure of a Cl‐boratabenzene species is reported.

show abstract

Coordination of a Di-tert-butylphosphidoboratabenzene Ligand to Electronically Unsaturated Group 10 Transition Metals

Abstract: This is the peer reviewed version of the following article: [Coordination to a Di-tertbutylphosphidoboratabenzene Ligand with Electronically Unsaturated Group 10 Transition Metals,

Cited by 26 publications

References 65 publications

Hybrid P,E Ligands: Synthesis, Coordination Chemistry and Catalysis

Hybrid P,E Ligands: Synthesis, Coordination Chemistry and Catalysis

Construction of Boron-Containing Aromatic Heterocycles

Generation of Group VI Piano‐Stool and Triple‐Decker Complexes from [(IMes)₂PtH(Cl‐boratabenzene)] Species

Contact Info

Product

Resources

About

Coordination of a Di-tert-butylphosphidoboratabenzene Ligand to Electronically Unsaturated Group 10 Transition Metals

Abstract: This is the peer reviewed version of the following article: [Coordination to a Di-tertbutylphosphidoboratabenzene Ligand with Electronically Unsaturated Group 10 Transition Metals,

Cited by 26 publications

References 65 publications

Hybrid P,E Ligands: Synthesis, Coordination Chemistry and Catalysis

Hybrid P,E Ligands: Synthesis, Coordination Chemistry and Catalysis

Construction of Boron-Containing Aromatic Heterocycles

Generation of Group VI Piano‐Stool and Triple‐Decker Complexes from [(IMes)2PtH(Cl‐boratabenzene)] Species

Contact Info

Product

Resources

About

Generation of Group VI Piano‐Stool and Triple‐Decker Complexes from [(IMes)₂PtH(Cl‐boratabenzene)] Species