Redox Chemistry and Group 10 Metal Complexes of Aromatic Compounds with Bulky Bicyclic Guanidino Groups

Wild, Ute; Kaifer, Elisabeth; Himmel, Hans‐Jörg

doi:10.1002/ejic.201100479

Cited by 13 publications

(3 citation statements)

References 69 publications

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“…323 and related bidentate systems, e.g., the guanidine–quinoline ligand 324 , were used by Herres-Pawlis and co-workers predominantly for the preparation of copper(I) − and zinc(II) − complexes, which were used, inter alia, as initiators for atom transfer radical polymerization (ATRP) of styrene and for the ring-opening polymerization (ROP) of lactide, respectively. For the latter application, zinc complexes with chiral bis(guanidine) ligands 325 and 326 and with camphor-derived guanidine ligands such as 327 were recently employed. , Himmel and co-workers developed several phenylene-bridged bis(imidazolidin-2-imine) ligands such as 328 and studied for instance their Ni(II), Co(II), Zn(II), and Cu(I)/Cu(II) complexes. − Bis(guanidines) with biphenyl, binaphthyl, and bipyridiyl cores, e.g., 329 were also prepared and used as proton sponges and chelate ligands, , while the guanidino-functionalized naphtyridine ligand 330 was used for the construction of copper chains in Cu 4 complexes . In addition, several electron-rich tetrakis- and even hexakis(guanidino) benzene systems such as 331 and 332 were prepared by the Himmel group ,− and used as redox-active compounds with multistage redox behavior or as ligands for the preparation of coordination polymers.…”

Section: N-heterocyclic Carbene Adducts Of Group 15 Elementsmentioning

confidence: 99%

N-Heterocyclic Carbene Adducts of Main Group Elements and Their Use as Ligands in Transition Metal Chemistry

2019

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N-Heterocyclic carbenes (NHC) are nowadays ubiquitous and indispensable in many research fields, and it is not possible to imagine modern transition metal and main group element chemistry without the plethora of available NHCs with tailor-made electronic and steric properties. While their suitability to act as strong ligands toward transition metals has led to numerous applications of NHC complexes in homogeneous catalysis, their strong σ-donating and adaptable π-accepting abilities have also contributed to an impressive vitalization of main group chemistry with the isolation and characterization of NHC adducts of almost any element. Formally, NHC coordination to Lewis acids affords a transfer of nucleophilicity from the carbene carbon atom to the attached exocyclic moiety, and low-valent and lowcoordinate adducts of the p-block elements with available lone pairs and/or polarized carbon-element π-bonds are able to act themselves as Lewis basic donor ligands toward transition metals. Accordingly, the availability of a large number of novel NHC adducts has not only produced new varieties of already existing ligand classes but has also allowed establishment of numerous complexes with unusual and often unprecedented element−metal bonds. This review aims at summarizing this development comprehensively and covers the usage of N-heterocyclic carbene adducts of the p-block elements as ligands in transition metal chemistry.

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Section: N-heterocyclic Carbene Adducts Of Group 15 Elementsmentioning

confidence: 99%

N-Heterocyclic Carbene Adducts of Main Group Elements and Their Use as Ligands in Transition Metal Chemistry

2019

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“…Platinum(II) imine complexes and imine-derived [ C , N ] and [ C , N,N ′] types of platinacycles have been studied intensively in the past due to their relevance in inorganic and organometallic syntheses, reactivity pattern, and structural aspects. − Further, these complexes exhibit interesting biological activity, , materials properties such as mesomorphism, liquid crystalline property, , and photophysical , and catalytic properties ). − Only two platinum(II) complexes of sym-N , N′,N″ -triphenylguanidine, PhNC(NHPh) 2 (LH 2 Ph ), have been structurally characterized, , although synthesis, reactivity studies, and structural aspects of platinum(II) complexes of other classes of guanidines have been steadily increasing since 1988. − …”

Section: Introductionmentioning

confidence: 99%

Dual Role of Acetate as a Nucleophile and as an Internal Base in Cycloplatination Reaction of sym-N,N′,N″-Triarylguanidines

2013

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Reaction of cis-[Cl(2)Pt(S(O)Me(2))(2)] with 1 equiv of sym-N,N',N″-triarylguanidines, ArN═C(NHAr)(2) (sym = symmetrical; Ar = 2-MeC(6)H(4) (LH(2)(2-tolyl)), 2-(MeO)C(6)H(4) (LH(2)(2-anisyl)), 4-MeC(6)H(4) (LH(2)(4-tolyl)), 2,5-Me(2)C(6)H(3) (LH(2)(2,5-xylyl)), and 2,6-Me(2)C(6)H(3) (LH(2)(2,6-xylyl))) in toluene under reflux condition for 3 h afforded cis- or trans-[Cl(2)Pt(S(O)Me(2))(ArN═C(NHAr)(2))] (Ar = 2-MeC(6)H(4) (1), 2-(MeO)C(6)H(4) (2), 4-MeC(6)H(4) (3), 2,5-Me(2)C(6)H(3) (4), and 2,6-Me(2)C(6)H(3) (5), respectively) in 83-96% yield. Reaction of cis-[Cl(2)Pt(S(O)Me(2))(2)] with 1 equiv of LH(2)(2-tolyl) and LH(2)(4-tolyl) in the presence of 1 equiv of NaOAc in methanol under reflux condition for 3 h afforded acetate-substituted products, cis-[(AcO)ClPt(S(O)Me(2))(ArN═C(NHAr)(2))] (Ar = 2-MeC(6)H(4) (6) and 4-MeC(6)H(4) (7)) in 83% and 84% yields, respectively. Reaction of cis-[Cl(2)Pt(S(O)Me(2))(2)] with 1 equiv of LH(2)(2-anisyl) and LH(2)(2-tolyl) in the presence of 1 equiv of NaOAc in methanol under reflux condition for 3 and 12 h afforded six-membered [C,N] platinacycles, [Pt{κ(2)(C,N)-C(6)H(3)R-3(NHC(NHAr)(═NAr))-2}Cl(S(O)Me(2))] (Ar = 2-RC(6)H(4); R = OMe (8) and Me (9)), in 92% and 79% yields, respectively. The new complexes have been characterized by analytical and spectroscopic techniques, and further the molecular structures of 1, 2, 4, 5, 6, and 8 have been determined by single-crystal X-ray diffraction. The platinum atom in 1, 4, and 5 exhibited the trans configuration, while that in 2, 6, and 8 exhibited the cis configuration. Complex 6 is shown to be the precursor for 9, and the former is suggested to transform to the latter possibly via an intramolecular C-H activation followed by elimination of AcOH. The solution behavior of new complexes has been studied by multinuclear NMR ((1)H, (195)Pt, and (13)C) spectroscopy. The new complexes exist exclusively as a single isomer (trans (1 and 5) and cis (6 and 7)), a mixture of cis and trans isomers with the former isomer being predominant in the case of 2 and the latter isomer being predominant in the case of 3. Complex 5 in the trans form revealed the presence of one isomer at 0.007 mM concentration and two isomers in about 1.00:0.12 ratio at 0.154 mM concentration as revealed by (1)H NMR spectroscopy, and this has been ascribed to the restricted Pt-S bond rotation at higher concentration. Platinacycle 8 exists as one isomer, while 9 exists as a mixture of seven isomers in solution. The influence of steric factor, π-acceptor property of the guanidine, subtle solid-state packing forces upon the configuration of the platinum atom, and the number of isomers in solution have been outlined. Factors that accelerate or slow down the cycloplatination reaction, the role of NaOAc, and a plausible mechanism of this reaction have been discussed.

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“…The structural characteristics of the anion are consistent within the observed values. (See for example, [63][64][65]).…”

Section: Compound (6)mentioning

confidence: 99%

Synthesis, Characterization and Photophysical Properties of Mixed Ligand (η3-Allyl)palladium(II) Complexes with N,N’Aromatic Diimines

Garypidou,

Ypsilantis,

Sifnaiou

et al. 2023

Chemistry

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Palladium(II) complexes of the general formula [Pd(η3-C3H5)(L)](PF6), where L is 4,7-diphenyl-1,10-phenanthroline (1), 2,9-dimethyl-1,10-phenanthroline (2), 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (3), 5-methyl-1,10-phenanthroline (4), 3,4,7,8-tetramethyl-1,10-phenanthroline (5), and 2-(2′-pyridyl) quinoxaline (6), were synthesized and characterized using high-resolution ESI-MS, NMR techniques and, in the case of (6), single-crystal X-ray diffraction methods. In addition, their photophysical properties were investigated. Complexes (1)–(6) were emitted in the greenish-blue region, with those containing methyl-substituted phenanthrolines having the higher quantum yield (≈14%) in the solid state.

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Redox Chemistry and Group 10 Metal Complexes of Aromatic Compounds with Bulky Bicyclic Guanidino Groups

Cited by 13 publications

References 69 publications

N-Heterocyclic Carbene Adducts of Main Group Elements and Their Use as Ligands in Transition Metal Chemistry

N-Heterocyclic Carbene Adducts of Main Group Elements and Their Use as Ligands in Transition Metal Chemistry

Dual Role of Acetate as a Nucleophile and as an Internal Base in Cycloplatination Reaction of sym-N,N′,N″-Triarylguanidines

Synthesis, Characterization and Photophysical Properties of Mixed Ligand (η3-Allyl)palladium(II) Complexes with N,N’Aromatic Diimines

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