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1. Isocyanide Activation by Phosphinimide-Ligated Cr(II) Centers

   https://doi.org/10.1021/acs.organomet.5c00278  

   Rathke, Paul; Rittle, Jonathan (November 2025, Organometallics)

   NA (Ed.)

   This report describes the synthesis and reactivity of the heteroleptic phosphinimide/phosphinimine Cr(II) complex HL′CrAdHMDS, which was obtained by incomplete protonolysis of Cr(HMDS)2(THF)2 in the presence of the bisphosphinimine pro-ligand H2L′Ad. Addition of common ligands such as N-heterocyclic carbenes and isocyanides displaces the remaining HMDS ligand concomitant with complete deprotonation of the phosphinimine pro-ligand furnishing three- and four-coordinated complexes, respectively. The resulting tetrahedral chromium(II) bis(isocyanide) species was found to adopt an unusual S = 1 spin state at room temperature. Under certain reaction conditions, one coordinated isocyanide ligand was found to insert into a chromium-phosphinimide bond. The described compounds are characterized by single-crystal X-ray diffraction and solution-phase spectroscopy, and the mechanism for isocyanide insertion was investigated by DFT calculations. 

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2. Synthesis, characterization, and liquid injection field desorption ionization mass spectrometry analysis of pincer ligated group 6 (Cr, Mo, W) carbonyl complexes

   https://doi.org/10.1177/14690667221149498  

   Duletski, Olivia L.; Arulsamy, Navamoney; Mock, Michael T. (February 2023, European Journal of Mass Spectrometry)

   We report the synthesis of molybdenum and tungsten bromo dicarbonyl complexes (POCOP t Bu )M II Br(CO) 2 (M  =  Mo or W; POCOP t Bu   =  κ 3 -C 6 H 3 -1,3-[OP( tBu) 2 ] 2 ) supported by an anionic PCP pincer ligand, and the chromium complex (PNP t Bu )Cr 0 (CO) 3 (PNP t Bu   =  2,6-bis(di- tert-butyl-phosphinomethyl)pyridine) bearing a neutral PNP pincer scaffold. The three group six complexes described in this study have been characterized by Liquid Injection Field Desorption Ionization Mass Spectrometry (LIFDI-MS), NMR, and IR spectroscopy. Single crystal X-ray diffraction studies show the Mo II and W II complexes adopt a six-coordinate distorted trigonal prismatic geometry, whereas the Cr 0 complex exhibits a distorted octahedral geometry. 

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3. Synthesis and structure of a tetrahedral homoleptic Cu ^I complex with xylyl isocyanide

   https://doi.org/10.1107/S2056989025009867  

   Chandima, A_M Buddhika; Groysman, Stanislav; Ward, Cassandra L (December 2025, Acta Crystallographica Section E Crystallographic Communications)

   Treatment of the Cu^Iprecursor [Cu(NCMe)₄]PF₆with excess (10 equivalents) of relatively bulky xylyl isocyanide formed a tetra(isocyanide) complex, namely, tetrakis(2,6-dimethylphenylisocyanide)copper(I) hexafluorophosphate, [Cu(C₉H₉N)₄]PF₆or [Cu(CNXyl)₄]PF₆, in good yield. This is in contrast to the previously reported reactions of Cu^Iprecursors with approximately three equivalents of xylyl isocyanide, which led selectively to the formation of tris(isocyanide) complexes. The copper atom lies on a twofold axis and P atom on an inversion centre. The complex was characterized by X-ray crystallography, IR spectroscopy, and¹H/¹³C {¹H} NMR spectroscopy. In the crystal structure, each individual [Cu(CNXyl)₄]⁺molecule demonstrates two pairs of coplanar xylyl isocyanide ligands. This arrangement leads to intermolecular π-stacking interactions between nearby complex molecules. 

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4. 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 (August 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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5. N ₃ -Ligated nickel( ii ) diketonate complexes: synthesis, characterization and evaluation of O ₂ reactivity

   https://doi.org/10.1039/d0dt01338b  

   Elsberg, Josiah G.; Peterson, Austin; Fuller, Amy L.; Berreau, Lisa M. (January 2020, Dalton Transactions)

   Interest in O 2 -dependent aliphatic carbon–carbon (C–C) bond cleavage reactions of first row divalent metal diketonate complexes stems from the desire to further understand the reaction pathways of enzymes such as DKE1 and to extract information to develop applications in organic synthesis. A recent report of O 2 -dependent aliphatic C–C bond cleavage at ambient temperature in Ni( ii ) diketonate complexes supported by a tridentate nitrogen donor ligand [(MBBP)Ni(PhC(O)CHC(O)Ph)]Cl ( 7-Cl ; MBBP = 2,6-bis(1-methylbenzimidazol-2-yl)pyridine) in the presence of NEt 3 spurred our interest in further examining the chemistry of such complexes. A series of new TERPY-ligated Ni( ii ) diketonate complexes of the general formula [(TERPY)Ni(R 2 -1,3-diketonate)]ClO 4 ( 1 : R = CH 3 ; 2 : R = C(CH 3 ) 3 ; 3 : R = Ph) was prepared under air and characterized using single crystal X-ray crystallography, elemental analysis, 1 H NMR, ESI-MS, FTIR, and UV-vis. Analysis of the reaction mixtures in which these complexes were generated using 1 H NMR and ESI-MS revealed the presence of both the desired diketonate complex and the bis-TERPY derivative [(TERPY) 2 Ni](ClO 4 ) 2 ( 4 ). Through selective crystallization 1–3 were isolated in analytically pure form. Analysis of reaction mixtures leading to the formation of the MBBP analogs [(MBBP)Ni(R 2 -1,3-diketonate)]X (X = ClO 4 : 5 : R = CH 3 ; 6 : R = C(CH 3 ) 3 ; 7-ClO4 : R = Ph; X = Cl: 7-Cl : R = Ph) using 1 H NMR and ESI-MS revealed the presence of [(MBBP) 2 Ni](ClO 4 ) 2 ( 8 ). Analysis of aerobic acetonitrile solutions of analytically pure 1–3 , 5 and 6 containing NEt 3 and in some cases H 2 O using 1 H NMR and UV-vis revealed evidence for the formation of additional bis-ligand complexes ( 4 and 8 ) but suggested no oxidative diketonate cleavage reactivity. Analysis of the organic products generated from 3 , 7-ClO4 and 7-Cl revealed unaltered dibenzoylmethane. Our results therefore indicate that N 3 -ligated Ni( ii ) complexes of unsubstituted diketonate ligands do not exhibit O 2 -dependent aliphatic C–C bond clevage at room temperature, including in the presence of NEt 3 and/or H 2 O. 

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