Recent Progress in the Chemistry of Metal Amidinates and Guanidinates

Edelmann, Frank T.

doi:10.1016/b978-0-12-407692-1.00002-3

Cited by 136 publications

(58 citation statements)

References 411 publications

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“…6b). Although the formation of this new anion is completely analogous to the widely employed reaction of carbodiimides with the M–C bonds of polar σ-organometallics5455, the only precedent for similar M–B insertion is provided by a scandium derivative, which was itself prepared from compound 1 (ref. 18).…”

Section: Resultsmentioning

confidence: 99%

Easy access to nucleophilic boron through diborane to magnesium boryl metathesis

et al. 2017

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Organoboranes are some of the most synthetically valuable and widely used intermediates in organic and pharmaceutical chemistry. Their synthesis, however, is limited by the behaviour of common boron starting materials as archetypal Lewis acids such that common routes to organoboranes rely on the reactivity of boron as an electrophile. While the realization of convenient sources of nucleophilic boryl anions would open up a wealth of opportunity for the development of new routes to organoboranes, the synthesis of current candidates is generally limited by a need for highly reducing reaction conditions. Here, we report a simple synthesis of a magnesium boryl through the heterolytic activation of the B–B bond of bis(pinacolato)diboron, which is achieved by treatment of an easily generated magnesium diboranate complex with 4-dimethylaminopyridine. The magnesium boryl is shown to act as an unambiguous nucleophile through its reactions with iodomethane, benzophenone and N,N′-di-isopropyl carbodiimide and by density functional theory.

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Section: Resultsmentioning

confidence: 99%

Easy access to nucleophilic boron through diborane to magnesium boryl metathesis

et al. 2017

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“…A generally applicable synthetic route to lithium amidinate precursors involves the addition of organolithium reagents to N,N -disubstituted carbodiimides, as shown in Scheme 2. The substituents R and R can be varied in a wide range and, consequently, a large library of amidinate ligands has become available [1][2][3][4][5][6][7][8][9]. Closely related guanidinate anions can be accessed in a similarly manner by adding lithium diorganoamides, LiNR 2 , to carbodiimides.…”

Section: Resultsmentioning

confidence: 99%

“…N,N -Chelating anionic ligands-such as the amidinates, [RC(NR ) 2 ] − , and guanidinates, [R 2 NC(NR ) 2 ] − (Scheme 1)-have become indispensable in various fields of organometallic and coordination chemistry [1][2][3][4][5][6][7][8][9]. These ligands form well-defined complexes with virtually every metallic element in the periodic system.…”

Section: Introductionmentioning

confidence: 99%

Unexpected Formation and Structural Characterization of a Dinuclear Sodium Half-Sandwich Complex

et al. 2018

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Treatment of N,N-diisopropylcarbodiimide with sodium cyclopentadienide (NaCp) in a molar ratio of 1:1 in THF solution resulted in formation of the unexpected dinuclear sodium half-sandwich complex [NaC 5 H 3 {C(NH i Pr)(=N i Pr)} 2-1,2] 2 (1) as colorless crystals in low yield. The newly formed ligand, which belongs to the group of 6-aminofulvene-2-aldiminate ligands, coordinates to sodium in an η 5-coordination mode via the cyclopentadienyl ring. Dimerization occurs through additional chelating κN,N-coordination of the amidine substituents. The NMR data of 1 indicated a slow dimer/monomer equilibrium in solution. A serendipitously isolated hydrolysis product, {µ-(i PrNH) 2 C=O} 2 [NaC 5 H 3 {C(NH i Pr)(=N i Pr)} 2-1,2] 2 (2), contains the new 6-aminofulvene-2-aldiminate ligand in the N,N-chelating coordination mode with the cyclopentadiene ring being uncoordinated. In this case, dimerization occurs through the presence of two bridging neutral N,N-diisopropylurea ligands. Both compounds have been structurally characterized by single-crystal X-ray diffraction.

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“…The chemistry of the neutral guanidines is very different from that of the formally related guanidinate anions which have already been known for a rich variety of coordination modes and excellent donor properties since the 1960s [2][3][4]. A special class of guanidinates are the imidazolin-2-iminato ligands which have been established as powerful ancillary ligands in catalysis [5].…”

Section: Introductionmentioning

confidence: 99%

Guanidine Metal Complexes for Bioinorganic Chemistry and Polymerisation Catalysis

Stanek

Rösener

Metz

et al. 2015

Topics in Heterocyclic Chemistry

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Guanidines are highly useful ligands which have conquered coordination chemistry within the last 20 years. Their CN 3 moiety allows multiple substitution patterns which enables tailoring them to a large variety of applications, ranging from bioinorganic coordination chemistry via medicinal chemistry to polymerisation catalysis. In bioinorganic chemistry, guanidines gave important stimuli in the modelling of copper type 1, 2 and 3 enzymes. This review provides with a comprehensive overview on complexes which have been reported with neutral guanidine ligands. Peralkylated guanidines as well as bicyclic or more complex guanidine-comprising entities are described in their coordination chemistry with transition and main-group metals. The structural features of the complexes as well as their most prominent features in bioinorganic chemistry or polymerisation catalysis are highlighted. Hereby, the role of the delocalisation of the positive charge within the guanidine unit gained during coordination is discussed in its importance for efficient and robust coordination. The delocalisation within the CN 3 unit can be measured by the structural value ρ which is discussed for numerous systems. The charge delocalisation makes neutral guanidines versatile and efficient for the stabilisation of highly different coordination modes and a large variety of oxidation states.

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Recent Progress in the Chemistry of Metal Amidinates and Guanidinates

Cited by 136 publications

References 411 publications

Easy access to nucleophilic boron through diborane to magnesium boryl metathesis

Easy access to nucleophilic boron through diborane to magnesium boryl metathesis

Unexpected Formation and Structural Characterization of a Dinuclear Sodium Half-Sandwich Complex

Guanidine Metal Complexes for Bioinorganic Chemistry and Polymerisation Catalysis

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