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1. En route to diplatinum polyynediyl complexes trans,trans-(Ar)(R3P)2Pt(C≡C)nPt(PR3)2(Ar): Untold tales, including end-group strategies

   https://doi.org/10.1351/pac200880030459  

   Stahl, Jürgen; Bohling, James C.; Peters, Thomas B.; de Quadras, Laura; Gladysz, John A. (January 2008, Pure and Applied Chemistry)

   Reactions of {(C 6 F 5 )Pt[S(CH 2 CH 2 -) 2 ](μ-Cl)} 2 and R 3 P yield the bis(phosphine) species trans -(C 6 F 5 )(R 3 P) 2 PtCl [R = Et ( Pt'Cl ), Ph, ( p -CF 3 C 6 H 4 ) 3 P; 88-81 %]. Additions of Pt'Cl and H(C≡C) n H ( n = 1, 2; HNEt 2 , 20 mol % CuI) give Pt'C 2 H (37 %, plus Pt'I , 16 %) and Pt'C 4 H (88 %). Homocoupling of Pt'C 4 H under Hay conditions (O 2 , CuCl, TMEDA, acetone) gives Pt'C 8 Pt' (85 %), but Pt'C 2 H affords only traces of Pt'C 4 Pt' . However, condensation of Pt'C 4 H and Pt'Cl (HNEt 2 , 20 mol % CuI) yields Pt'C 4 Pt' (97 %). Hay heterocouplings of Pt'C 4 H or trans -( p -tol)(Ph 3 P) 2 Pt(C≡C) 2 H ( Pt*C 4 H ) and excess HC≡CSiEt 3 give Pt'C 6 SiEt 3 (76 %) or Pt*C 6 SiEt 3 (89 %). The latter and wet n -Bu 4 N + F - react to yield labile Pt*C 6 H (60 %). Hay homocouplings of Pt*C 4 H and Pt*C 6 H give Pt*C 8 Pt* (64 %) and Pt*C 12 Pt* (64 %). Reaction of trans -(C 6 F 5 )( p -tol 3 P) 2 PtCl ( PtCl ) and HC≡CH (HNEt 2 , 20 mol % CuI) yields only traces of PtC 2 H . However, an analogous reaction with HC≡CSiMe 3 gives PtC 2 SiMe 3 (75 %), which upon treatment with silica yields PtC 2 H (77 %). An analogous coupling of trans -(C 6 F 5 )(Ph 3 P) 2 PtCl with H(C≡C) 2 H gives trans -(C 6 F 5 )(Ph 3 P) 2 Pt(C≡C) 2 H (34 %). Advantages and disadvantages of the various trans -(Ar)(R 3 P) 2 Pt end-groups are analyzed. 

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2. Platinum( ii ) alkyl complexes of chelating dibridgehead diphosphines P((CH ₂ ) _n ) ₃ P ( n = 14, 18, 22); facile cis / trans isomerizations interconverting gyroscope and parachute like adducts

   https://doi.org/10.1039/D1DT02321G  

   Zhu, Yun; Ehnbom, Andreas; Fiedler, Tobias; Shu, Yi; Bhuvanesh, Nattamai; Hall, Michael B.; Gladysz, John A. (September 2021, Dalton Transactions)

   The gyroscope like dichloride complexes trans -Pt(Cl) 2 (P((CH 2 ) n ) 3 P) ( trans -2; n = c, 14; e, 18; g, 22) and MeLi (2 equiv.) react to yield the parachute like dimethyl complexes cis -Pt(Me) 2 (P((CH 2 ) n ) 3 P) ( cis -4c,e,g, 70–91%). HCl (1 equiv.) and cis -4c react to give cis -Pt(Cl)(Me)(P((CH 2 ) 14 ) 3 P) ( cis -5c, 83%), which upon stirring with silica gel or crystallization affords trans -5c (89%). Similar reactions of HCl and cis -4e,g give cis / trans -5e,g mixtures that upon stirring with silica gel yield trans -5e,g. A parallel sequence with trans -2c/EtLi gives cis -Pt(Et) 2 (P((CH 2 ) 14 ) 3 P) ( cis -6c, 85%) but subsequent reaction with HCl affords trans -Pt(Cl)(Et)(P((CH 2 ) 14 ) 3 P) ( trans -7c, 45%) directly. When previously reported cis -Pt(Ph) 2 (P((CH 2 ) 14 ) 3 P) is treated with HCl (1 equiv.), cis - and trans -Pt(Cl)(Ph)(P((CH 2 ) 14 ) 3 P) are isolated (44%, 29%), with the former converting to the latter at 100 °C. Reactions of trans -5c and LiBr or NaI afford the halide complexes trans -Pt(X)(Me)(P((CH 2 ) 14 ) 3 P) ( trans -9c, 88%; trans -10c, 87%). Thermolyses and DFT calculations that include acyclic model compounds establish trans > cis stabilities for all except the dialkyl complexes, for which energies can be closely spaced. The σ donor strengths of the non-phosphine ligands are assigned key roles in the trends. The crystal structures of cis -4c, trans -5c, trans -7c, and trans -10c are determined and analyzed together with the computed structures. 

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3. Dimetalloylene (M‐E‐M) Complexes of Heavier Main Group Elements Ge, Sn, Pb, Bi via Cleavage of E‐X Bonds (X=N(SiMe ₃ ) ₂ , O t Bu) with an Iridium Hydride

   https://doi.org/10.1002/chem.202301863  

   Saint‐Denis, Tyler G.; Zhang, Bowen; Settineri, Nicholas S.; Handford, Rex C.; Hall, Michael B.; Tilley, T. Don (September 2023, Chemistry – A European Journal)

   Abstract Reactions of the Ir V hydride [ Me BDI Dipp ]IrH 4 {BDI=(Dipp)NC(Me)CH(Me)CN(Dipp); Dipp=2,6‐ i Pr 2 C 6 H 3 } with E[N(SiMe 3 ) 2 ] 2 (E=Sn, Pb) afforded the unusual dimeric dimetallotetrylenes ([ Me BDI Dipp ]IrH) 2 ( μ 2 ‐E) 2 in good yields. Moreover, ([ Me BDI Dipp ]IrH) 2 ( μ 2 ‐Ge) 2 was formed in situ from thermal decomposition of [ Me BDI Dipp ]Ir(H) 2 Ge[N(SiMe 3 ) 2 ] 2 . These reactions are accompanied by liberation of HN(SiMe 3 ) 2 and H 2 through the apparent cleavage of an E−N(SiMe 3 ) 2 bond by Ir−H. In a reversal of this process, ([ Me BDI Dipp ]IrH) 2 ( μ 2 ‐E) 2 reacted with excess H 2 to regenerate [ Me BDI Dipp ]IrH 4 . Varying the concentrations of reactants led to formation of the trimeric ([ Me BDI Dipp ]IrH 2 ) 3 ( μ 2 ‐E) 3 . The further scope of this synthetic route was investigated with group 15 amides, and ([ Me BDI Dipp ]IrH) 2 ( μ 2 ‐Bi) 2 was prepared by the reaction of [ Me BDI Dipp ]IrH 4 with Bi(NMe 2 ) 3 or Bi(O t Bu) 3 to afford the first example of a “naked” two‐coordinate Bi atom bound exclusively to transition metals. A viable mechanism that accounts for the formation of these products is proposed. Computational investigations of the Ir 2 E 2 (E=Sn, Pb) compounds characterized them as open‐shell singlets with confined nonbonding lone pairs at the E centers. In contrast, Ir 2 Bi 2 is characterized as having a closed‐shell singlet ground state. 

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4. P-Alkynyl functionalized benzazaphospholes as transmetalating agents

   https://doi.org/10.1039/d0dt01367f  

   Zhou, Daniel Y.; Miura-Akagi, Preston M.; McCarty, Sierra M.; Guiles, Celeste H.; O'Donnell, Timothy J.; Yoshida, Wesley Y.; Krause, Colleen E.; Rheingold, Arnold L.; Hughes, Russell P.; Cain, Matthew F. (January 2021, Dalton Transactions)

   null (Ed.)

   Exposure of 10π-electron benzazaphosphole 1 to HCl, followed by nucleophilic substitution with the Grignard reagent BrMgCCPh afforded alkynyl functionalized 3 featuring an exocyclic –CC–Ph group with an elongated P–C bond (1.7932(19) Å). Stoichiometric experiments revealed that treatment of trans -Pd(PEt 3 ) 2 (Ar)( i ) (Ar = p -Me ( C ) or p -F ( D )) with 3 generated trans -Pd(PEt 3 ) 2 (Ar)(CCPh) (Ar = p -Me ( E ) or p -F ( F )), 5 , which is the result of ligand exchange between P–I byproduct 4 and C/D , and the reductively eliminated product (Ar–CC–Ph). Cyclic voltammetry studies showed and independent investigations confirmed 4 is also susceptible to redox processes including bimetallic oxidative addition to Pd(0) to give Pd( i ) dimer 6-Pd2-(P(t-Bu)3)2 and reduction to diphosphine 7 . During catalysis, we hypothesized that this unwanted reactivity could be circumvented by employing a source of fluoride as an additive. This was demonstrated by conducting a Sonogashira-type reaction between 1-iodotoluene and 3 in the presence of 10 mol% Na 2 PdCl 4 , 20 mol% P( t -Bu)Cy 2 , and 5 equiv. of tetramethylammonium fluoride (TMAF), resulting in turnover and the isolation of Ph–CC–( o -Tol) as the major product. 

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5. Macrocyclic Complexes Derived from Four cis-L2Pt Corners and Four Butadiynediyl Linkers; Syntheses, Electronic Structures, and Square versus Skew Rhombus Geometries

   https://doi.org/10.1002/chem.202100305  

   Collins, Brenna; Mastry, Melissa Clough; Ehnbom, Andreas; Bhuvanesh, Nattamai; Hall, Michael B.; Gladysz, John A. (January 2021, Chemistry)

   The dialkyl malonate derived 1,3-diphosphines R2C(CH2PPh2)2 (R=a, Me; b, Et; c, n-Bu; d, n-Dec; e, Bn; f, p-tolCH2) are combined with (p-tol3P)2PtCl2 or trans-(p-tol3P)2Pt((C≡C)2H)2 to give the chelates cis-(R2C(CH2PPh2)2)PtCl2 (2 a–f, 94–69 %) or cis-(R2C(CH2PPh2)2)Pt((C≡C)2H)2 (3 a–f, 97–54 %). Complexes 3 a–d are also available from 2 a–d and excess 1,3-butadiyne in the presence of CuI (cat.) and excess HNEt2 (87–65 %). Under similar conditions, 2 and 3 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 of 4 a,b show skew rhombus as opposed to square Pt4 geometries. The NMR and IR properties of 4 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 Pt4C16 cores that likely facilitate ammonium cation binding. Analogous electronic properties of Pt3C12 and Pt5C20 homologs and selected equilibria are explored computationally. 

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