The dialkyl malonate derived 1,3‐diphosphines R2C(CH2PPh2)2(R=
Reduction of the cobalt(II) chloride complex, Ph2B(tBuIm)2Co(THF)Cl (
- Award ID(s):
- 1908587
- NSF-PAR ID:
- 10390943
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- European Journal of Inorganic Chemistry
- Volume:
- 26
- Issue:
- 8
- ISSN:
- 1434-1948
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract a , Me;b , Et;c ,n ‐Bu;d ,n ‐Dec;e , Bn;f ,p ‐tolCH2) are combined with (p ‐tol3P)2PtCl2ortrans ‐(p‐ tol3P)2Pt((C≡C)2H)2to give the chelatescis ‐(R2C(CH2PPh2)2)PtCl2(2 a –f , 94–69 %) orcis ‐(R2C(CH2PPh2)2)Pt((C≡C)2H)2(3 a –f , 97–54 %). Complexes3 a –d are also available from2 a –d and excess 1,3‐butadiyne in the presence of CuI (cat.) and excess HNEt2(87–65 %). Under similar conditions,2 and3 react to give the title compounds [(R2C(CH2PPh2)2)[Pt(C≡C)2]4(4 a –f ; 89–14 % (64 % avg)), from which ammonium salts such as the co‐product [H2NEt2]+Cl−are challenging to remove. Crystal structures of4 a ,b show skew rhombus as opposed to square Pt4geometries. The NMR and IR properties of4 a –f are similar to those of mono‐ or diplatinum model compounds. However, cyclic voltammetry gives only irreversible oxidations. As compared to mono‐platinum or Pt(C≡C)2Pt species, the UV‐visible spectra show much more intense and red‐shifted bands. Time dependent DFT calculations define the transitions and principal orbitals involved. Electrostatic potential surface maps reveal strongly negative Pt4C16cores that likely facilitate ammonium cation binding. Analogous electronic properties of Pt3C12and Pt5C20homologs and selected equilibria are explored computationally. -
Abstract 3,3′,5,5′‐Tetra‐
tert ‐butyl‐2′‐sulfanyl[1,1′‐biphenyl]‐2‐ol (H2[t Bu4OS]) was prepared in 24 % yield overall from the analogous biphenol using standard techniques. Addition of H2[t Bu4OS] to Mo(NAr)(CHCMe2Ph)(2,5‐dimethylpyrrolide)2led to formation of Mo(NAr)(CHCMe2Ph)[t Bu4OS], which was trapped with PMe3to give Mo(NAr)(CHCMe2Ph)[t Bu4OS](PMe3) (1 (PMe3)). An X‐ray crystallographic study of1 (PMe3) revealed that two structurally distinct square pyramidal molecules are present in which the alkylidene ligand occupies the apical position in each. Both1 (PMe3)Aand1 (PMe3)Bare disordered. Mo(NAd)(CHCMe2Ph)(t Bu4OS)(PMe3) (2 (PMe3); Ad=1‐adamantyl) and W(NAr)(CHCMe2Ph)(t Bu4OS)(PMe3) (3 (PMe3)) were prepared using analogous approaches.1 (PMe3) reacts with ethylene (1 atm) in benzene within 45 minutes to give an ethylene complex Mo(NAr)(t Bu4OS)(C2H4) (4 ) that is isolable and relatively stable toward loss of ethylene below 60 °C. An X‐ray study shows that the bond distances and angles for the ethylene ligand in4 are like those found for bisalkoxide ethylene complexes of the same general type. Complex1 (PMe3) in the presence of one equivalent of B(C6F5)3catalyzes the homocoupling of 1‐decene, allyltrimethylsilane, and allylboronic acid pinacol ester at ambient temperature.1 (PMe3),2 (PMe3), and3 (PMe3) all catalyze the ROMP ofrac ‐endo ,exo ‐5,6‐dicarbomethoxynorbornene (rac ‐DCMNBE) in the presence of B(C6F5)3, but the polyDCMNBE that is formed has a random structure. -
Abstract A low‐spin and mononuclear vanadium complex, (Menacnac)V(CO)(η2‐P≡C
t Bu) (2 ) (Menacnac−=[ArNC(CH3)]2CH, Ar=2,6‐i Pr2C6H3), was prepared upon treatment of the vanadium neopentylidyne complex (Menacnac)V≡Ct Bu(OTf) (1 ) with Na(OCP)(diox)2.5(diox=1,4‐dioxane), while the isoelectronic ate‐complex [Na(15‐crown‐5)]{([ArNC(CH2)]CH[C(CH3)NAr])V(CO)(η2‐P≡Ct Bu)} (4 ), was obtained via the reaction of Na(OCP)(diox)2.5and ([ArNC(CH2)]CH[C(CH3)NAr])V≡Ct Bu(OEt2) (3 ) in the presence of crown‐ether. Computational studies suggest that the P‐atom transfer proceeds by [2+2]‐cycloaddition of the P≡C bond across the V≡Ct Bu moiety, followed by a reductive decarbonylation to form the V−C≡O linkage. The nature of the electronic ground state in diamagnetic complexes,2 and4 , was further investigated both theoretically and experimentally, using a combination of density functional theory (DFT) calculations, UV/Vis and NMR spectroscopies, cyclic voltammetry, X‐ray absorption spectroscopy (XAS) measurements, and comparison of salient bond metrics derived from X‐ray single‐crystal structural characterization. In combination, these data are consistent with a low‐valent vanadium ion in complexes2 and4 . This study represents the first example of a metathesis reaction between the P‐atom of [PCO]−and an alkylidyne ligand. -
Abstract A low‐spin and mononuclear vanadium complex, (Menacnac)V(CO)(η2‐P≡C
t Bu) (2 ) (Menacnac−=[ArNC(CH3)]2CH, Ar=2,6‐i Pr2C6H3), was prepared upon treatment of the vanadium neopentylidyne complex (Menacnac)V≡Ct Bu(OTf) (1 ) with Na(OCP)(diox)2.5(diox=1,4‐dioxane), while the isoelectronic ate‐complex [Na(15‐crown‐5)]{([ArNC(CH2)]CH[C(CH3)NAr])V(CO)(η2‐P≡Ct Bu)} (4 ), was obtained via the reaction of Na(OCP)(diox)2.5and ([ArNC(CH2)]CH[C(CH3)NAr])V≡Ct Bu(OEt2) (3 ) in the presence of crown‐ether. Computational studies suggest that the P‐atom transfer proceeds by [2+2]‐cycloaddition of the P≡C bond across the V≡Ct Bu moiety, followed by a reductive decarbonylation to form the V−C≡O linkage. The nature of the electronic ground state in diamagnetic complexes,2 and4 , was further investigated both theoretically and experimentally, using a combination of density functional theory (DFT) calculations, UV/Vis and NMR spectroscopies, cyclic voltammetry, X‐ray absorption spectroscopy (XAS) measurements, and comparison of salient bond metrics derived from X‐ray single‐crystal structural characterization. In combination, these data are consistent with a low‐valent vanadium ion in complexes2 and4 . This study represents the first example of a metathesis reaction between the P‐atom of [PCO]−and an alkylidyne ligand. -
Abstract We introduce the heterocumulene ligand [(Ad)NCC(
t Bu)]−(Ad=1‐adamantyl (C10H15),t Bu=tert ‐butyl, (C4H9)), which can adopt two forms, the azaalleneyl and ynamide. This ligand platform can undergo a reversible chelotropic shift using Brønsted acid‐base chemistry, which promotes an unprecedented spin‐state change of the [VIII] ion. These unique scaffolds are prepared via addition of 1‐adamantyl isonitrile (C≡NAd) across the alkylidyne in complexes [(BDI)V≡Ct Bu(OTf)] (A ) (BDI−=ArNC(CH3)CHC(CH3)NAr), Ar=2,6‐i Pr2C6H3) and [(dBDI)V≡Ct Bu(OEt2)] (B ) (dBDI2−=ArNC(CH3)CHC(CH2)NAr). ComplexA reacts with C≡NAd, to generate the high‐spin [VIII] complex with a κ1‐N ‐ynamide ligand, [(BDI)V{κ1‐N ‐(Ad)NCC(t Bu)}(OTf)] (1 ). Conversely,B reacts with C≡NAd to generate a low‐spin [VIII] diamagnetic complex having a chelated κ2‐C ,N ‐azaalleneyl ligand, [(dBDI)V{κ2‐N ,C ‐(Ad)NCC(t Bu)}] (2 ). Theoretical studies have been applied to better understand the mechanism of formation of2 and the electronic reconfiguration upon structural rearrangement by the alteration of ligand denticity between1 and2 .