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1. Coinage Metal Complexes of a Sterically Encumbered Anionic Pyridylborate

   https://doi.org/10.1002/chem.202401204  

   Vanga, Mukundam; Muñoz‐Castro, Alvaro; Dias, H_V_Rasika (June 2024, Chemistry – A European Journal)

   Abstract Sterically loaded, anionic pyridine has been synthesized and utilized successfully in the stabilization of a isoleptic series of coinage metal complexes. The treatment of [4‐(Ph₃B)‐2,6‐Trip₂Py]K (Trip=2,4,6‐ⁱPr₃C₆H₂) with CuBr(PPh₃), AgCl(PPh₃) or AuCl(PPh₃) (Py=pyridine) afforded the corresponding [4‐(Ph₃B)‐2,6‐Trip₂Py]M(PPh₃) (M=Au, Ag, Cu) complexes, via salt metathesis, as isolable, crystalline solids. Notably, these reactions avoid the facile single electron transfer chemistry reported with the less bulky ligand systems. The X‐ray structures revealed that they are two‐coordinate metal adducts. The M−N and M−P bond distances are longest in the silver and shortest in the copper adduct among the three group 11 family members. Computational analysis revealed an interesting stability dependence on steric bulk of the anionic pyridine (i. e., pyridyl borate) ligand. A comparison of structures and bonding of [4‐(Ph₃B)‐2,6‐Trip₂Py]Au(PPh₃) to pyridine andm‐terphenyl complexes, {[2,6‐Trip₂Py]Au(PPh₃)}[SbF₆] and [2,6‐Trip₂Ph]Au(PPh₃) are also provided. The Au(I) isocyanide complex, [4‐(Ph₃B)‐2,6‐Trip₂Py]Au(CNBu^t) has been stabilized using the same anionic pyridylborate illustrating that it can support other gold‐ligand moieties as well. 

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2. A new supramolecular bonding motif involving NH bonds of ammonium salts and macrocycles derived from platinum corners and butadiynediyl linkers

   https://doi.org/10.1039/D2DT02680E  

   Collins, Brenna K.; Bhuvanesh, Nattamai; Gladysz, John A. (November 2022, Dalton Transactions)

   CuI catalyzes reactions of cis -(R 2 C(CH 2 PPh 2 ) 2 )Pt(CCCCH) 2 and cis -(R 2 C(CH 2 PPh 2 ) 2 )PtI 2 in secondary amine solvents HNR’ 2 to give the title adducts [(R 2 C(CH 2 PPh 2 ) 2 )Pt(CCCC)] 4 ·(H 2 NR’ 2 + I − ) n (R/R’/ n = Me/Et/1, Me/((CH 2 CH 2 ) 2 O) 0.5 /3, Et/Et/1, Et/CH 2 CHCH 2 /1; 92–42%). Crystal structures of these or closely related species establish folded Pt 4 cores containing ammonium cation guests, with NH/ and NCH/CC hydrogen bonding. DOSY NMR experiments show that the host/guest relationship can be maintained in solution. 

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3. Inorganic clusters as metalloligands: ligand effects on the synthesis and properties of ternary nanopropeller clusters

   https://doi.org/10.1039/D0DT02416C  

   Kephart, Jonathan A.; Boggiano, Andrew C.; Kaminsky, Werner; Velian, Alexandra (November 2020, Dalton Transactions)

   null (Ed.)

   Redox-active multimetallic platforms with synthetically addressable and hemilabile active sites are attractive synthetic targets for mimicking the reactivity of enzymatic co-factors toward multielectron transformations. To this end, a family of ternary clusters featuring three edge metal sites anchored on a [Co 6 Se 8 ] multimetallic support via amidophosphine ligands are a promising platform. In this report, we explore how small changes in the stereoelectronic properties of these ligands alter [Co 6 Se 8 ] metalloligand formation, but also substrate binding affinity and strength of the edge/support interaction in two new ternary clusters, M 3 Co 6 Se 8 L 6 (M = Zn, Fe; L (−) = Ph 2 PN (−)i Pr). These clusters are characterized extensively using a range of methods, including single crystal X-ray diffraction, electronic absorption spectroscopy and cyclic voltammetry. Substrate binding studies reveal that Fe 3 Co 6 Se 8 L 6 resists coordination of larger ligands like pyridine or tetrahydrofuran, but binds the smaller ligand CN t Bu. Additionally, investigations into the synthesis of new [Co 6 Se 8 ] metalloligands using two aminophosphines, Ph 2 PN(H) i Pr (L H ) and i Pr 2 PN(H) i Pr, led to the synthesis and characterization of Co 6 Se 8 L H 6 , as well as the smaller clusters Co 4 Se 2 (CO) 6 L H 4 , Co 3 Se(μ 2 -PPh 2 )(CO) 4 L H 3 , and [Co(CO) 3 ( i Pr 2 PN(H) i Pr)] 2 . Cumulatively, this study expands our understanding on the effect of the stereoelectronic properties of aminophosphine ligands in the synthesis of cobalt chalcogenide clusters, and, importantly on modulating the push–pull dynamic between the [Co 6 Se 8 ] support, the edge metals and incoming coordinating ligands in ternary M 3 Co 6 Se 8 L 6 clusters. 

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4. 4,5-Diazafluorene and 9,9’-Dimethyl-4,5-Diazafluorene as Ligands Supporting Redox-Active Mn and Ru Complexes

   https://doi.org/10.3390/molecules25143189  

   Henke, Wade C.; Hopkins, Julie A.; Anderson, Micah L.; Stiel, Jonah P.; Day, Victor W.; Blakemore, James D. (July 2020, Molecules)

   null (Ed.)

   4,5-diazafluorene (daf) and 9,9’-dimethyl-4,5-diazafluorene (Me2daf) are structurally similar to the important ligand 2,2’-bipyridine (bpy), but significantly less is known about the redox and spectroscopic properties of metal complexes containing Me2daf as a ligand than those containing bpy. New complexes Mn(CO)3Br(daf) (2), Mn(CO)3Br(Me2daf) (3), and [Ru(Me2daf)3](PF6)2 (5) have been prepared and fully characterized to understand the influence of the Me2daf framework on their chemical and electrochemical properties. Structural data for 2, 3, and 5 from single-crystal X-ray diffraction analysis reveal a distinctive widening of the daf and Me2daf chelate angles in comparison to the analogous Mn(CO)3(bpy)Br (1) and [Ru(bpy)3]2+ (4) complexes. Electronic absorption data for these complexes confirm the electronic similarity of daf, Me2daf, and bpy, as spectra are dominated in each case by metal-to-ligand charge transfer bands in the visible region. However, the electrochemical properties of 2, 3, and 5 reveal that the redox-active Me2daf framework in 3 and 5 undergoes reduction at a slightly more negative potential than that of bpy in 1 and 4. Taken together, the results indicate that Me2daf could be useful for preparation of a variety of new redox-active compounds, as it retains the useful redox-active nature of bpy but lacks the acidic, benzylic C–H bonds that can induce secondary reactivity in complexes bearing daf. 

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5. Platinum Elimination from Bis(triethylsilylpolyynyl) Complexes ( n ‐Bu ₂ C(CH ₂ PPh ₂ ) ₂ )Pt((C≡C) _n SiEt ₃ ) ₂ ( n =2, 3) and Macrocycles Comprised of Four L ₂ Pt Corners and Four C≡CC≡CC≡C Linkers; An Approach to Cyclo[24]carbon

   https://doi.org/10.1002/chem.202402833  

   Collins, Brenna_K; Gladysz, John_A (October 2024, Chemistry – A European Journal)

   Abstract The overarching goal of this study is to effect the elimination of platinum from adducts withcis–C≡C−Pt−C≡C‐ linkages, thereby generating novel conjugated polyynes. Thus, the bis(hexatriynyl) complextrans‐(p‐tol₃P)₂Pt((C≡C)₃H)₂is treated with 1,3‐diphosphines R₂C(CH₂PPh₂)₂to generate (R₂C(CH₂PPh₂)₂)₂Pt((C≡C)₃H)₂(14; R=c,n‐Bu;e,p‐tolCH₂). These condense with the diiodide complexes R₂C(CH₂PPh₂)₂PtI₂(9 a,c) in the presence of CuI (cat.) and excess HNEt₂to give the title macrocycles [(R₂C(CH₂PPh₂)₂)Pt(C≡C)₃]₄(16 c,e) as adducts of the byproduct [H₂NEt₂]⁺I⁻(30–66 %). DOSY NMR experiments establish that this association is maintained in solution, but NaOAc removes the ammonium salt. The bis(triethylsilylpolyynyl) complexes (n‐Bu₂C(CH₂PPh₂)₂)Pt((C≡C)_nSiEt₃)₂(n=2, 3) are synthesized analogously to14 c. They react with I₂at rt to give mainly the diiodide complex9 cand the coupling product Et₃Si(C≡CC≡C)_nSiEt₃. The possibility of competing reactions giving IC≡C species is investigated. Analogous reactions of the Pt₄C₂₄macrocycle16 calso give9 c, but no sp¹³C NMR signals or mass spectrometric C_x^z+ions (x=24–100) could be detected. It is proposed that some cyclo[24]carbon is generated, but then rapidly converts to other forms of elemental carbon. No cyclotetracosane (C₂₄H₄₈) is detected when this sequence is carried out in the presence of PtO₂and H₂. 

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