An official website of the United States government
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(CNBut) has been stabilized using the same anionic pyridylborate illustrating that it can support other gold‐ligand moieties as well.
more »
« less
Hydrogen bonds and dispersion forces serving as molecular locks for tailored Group 11 bis(amidine) complexes
A flexible polydentate bis(amidine) ligand LH 2 , LH 2 = {CH 2 NH( t Bu)CN-2-(6-MePy)} 2 , operates as a molecular lock for various coinage metal fragments and forms the dinuclear complexes [LH 2 (MCl) 2 ], M = Cu (1), Au (2), the coordination polymer [{(LH 2 ) 2 (py) 2 (AgCl) 3 }(py) 3 ] n (3), and the dimesityl-digold complex [LH 2 (AuMes) 2 ] (4) by formal insertion of MR fragments (M = Cu, Ag, Au; R = Cl, Mes) into the N–H⋯N hydrogen bonds of LH 2 in yields of 43–95%. Complexes 1, 2, and 4 adopt C 2 -symmetrical structures in the solid state featuring two interconnected 11-membered rings that are locked by two intramolecular N–H⋯R–M hydrogen bonds. QTAIM analyses of the computational geometry-optimized structures 1a, 2a, and 4a reveal 13, 11, and 22 additional bond critical points, respectively, all of which are related to weak intramolecular attractive interactions, predominantly representing dispersion forces, contributing to the conformational stabilization of the C 2 -symmetrical stereoisomers in the solid state. Variable-temperature 1 H NMR spectroscopy in combination with DFT calculations indicate a dynamic conformational interconversion between two C 2 -symmetrical ground state structures in solution (Δ G ‡c = 11.1–13.8 kcal mol −1 ), which is accompanied by the formation of an intermediate possessing C i symmetry that retains the hydrogen bonds.
more »
« less
- Award ID(s):
- 1800332
- PAR ID:
- 10330598
- Date Published:
- Journal Name:
- Inorganic Chemistry Frontiers
- ISSN:
- 2052-1553
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Transition metal interactions with Lewis acids (M → Z linkages) are fundamentally interesting and practically important. The most common Z-type ligands contain boron, which contains an NMR active 11 B nucleus. We measured solid-state 11 B{ 1 H} NMR spectra of copper, silver, and gold complexes containing a phosphine substituted 9,10-diboraanthracene ligand (B 2 P 2 ) that contain planar boron centers and weak M → BR 3 linkages ([(B 2 P 2 )M][BAr F 4 ] (M = Cu (1), Ag (2), Au (3)) characterized by large quadrupolar coupling ( C Q ) values (4.4–4.7 MHz) and large span ( Ω ) values (93–139 ppm). However, the solid-state 11 B{ 1 H} NMR spectrum of K[Au(B 2 P 2 )] − (4), which contains tetrahedral borons, is narrow and characterized by small C Q and Ω values. DFT analysis of 1–4 shows that C Q and Ω are expected to be large for planar boron environments and small for tetrahedral boron, and that the presence of a M → BR 3 linkage relates to the reduction in C Q and 11 B NMR shielding properties. Thus solid-state 11 B NMR spectroscopy contains valuable information about M → BR 3 linkages in complexes containing the B 2 P 2 ligand.more » « less
-
null (Ed.)Copper( i ) and silver( i ) pyrazolate complexes {[3,5-(3,5-(CF 3 ) 2 Ph) 2 Pz]Cu} 3 and {[3,5-(3,5-(CF 3 ) 2 Ph) 2 Pz]Ag} 3 have been synthesized using the fluorinated 3,5-(diaryl)pyrazole 3,5-(3,5-(CF 3 ) 2 Ph) 2 PzH and copper( i ) oxide and silver( i ) oxide, respectively. The gold( i ) analog was obtained from a reaction between Au(THT)Cl and [3,5-(3,5-(CF 3 ) 2 Ph) 2 Pz]H/NaH. The X-ray crystal structures show that the coinage metal complexes {[3,5-(3,5-(CF 3 ) 2 Ph) 2 Pz]M} 3 (M = Cu, Ag, Au) are trinuclear in the solid state. They feature distorted nine-membered M 3 N 6 metallacyclic cores. The M–N distances follow Cu < Au < Ag, which is the trend expected from covalent radii of the corresponding coinage metal ions. The 3,5-(3,5-(CF 3 ) 2 Ph) 2 PzH forms hydrogen bonded trimers in the solid state that are further organized by π-stacking between aryl rings. Solid samples of {[3,5-(3,5-(CF 3 ) 2 Ph) 2 Pz]M} 3 display blue photoluminescence. The copper complex {[3,5-(3,5-(CF 3 ) 2 Ph) 2 Pz]Cu} 3 is an excellent catalyst for mediating azide–alkyne cycloaddition chemistry.more » « less
-
null (Ed.)We report the design, synthesis, and crystal structure of a conjugated aryleneethynyl molecule, 2-(2-{4,5-dimethoxy-2-[2-(2,3,4-trifluorophenyl)ethynyl]phenyl}ethynyl)-6-[2-(pyridin-2-yl)ethynyl]pyridine, C 30 H 17 F 3 N 2 O 2 , that adopts a planar rhombus conformation in the solid state. The molecule crystallizes in the space group P -1, with Z = 2, and features two intramolecular sp 2 -C—H...N hydrogen bonds that co-operatively hold the arylethynyl molecule in a rhombus conformation. The H atoms are activated towards hydrogen bonding since they are situated on a trifluorophenyl ring and the H...N distances are 2.470 (16) and 2.646 (16) Å, with C—H...N angles of 161.7 (2) and 164.7 (2)°, respectively. Molecular electrostatic potential calculations support the formation of C—H...N hydrogen bonds to the trifluorophenyl moiety. Hirshfeld surface analysis identifies a self-complementary C—H...O dimeric interaction between adjacent 1,2-dimethoxybenzene segments that is shown to be common in structures containing that moiety.more » « less
-
During the course of exploring crystallization conditions in generating metal–organic frameworks (MOFs) for use in the crystalline sponge method, two discrete metal–organic complexes, namely, aqua[2,4,6-tris(pyridin-4-yl)-1,3,5-triazine]zinc(II) bromide, [Zn(C18H12N6)(H2O)]Br2, and aqua[2,4,6-tris(pyridin-4-yl)-1,3,5-triazine]zinc(II) chloride, [Zn(C18H12N6)(H2O)]Cl2, were encountered. Structures in the orthorhombic space groupPnma(No. 62) for the bromide congener at 299 K and the chloride congener at 100 K were obtained. A phase transition for the bromide congener occurred upon cooling from 299 to 100 K, yielding a crystal polymorph with four domains that exhibits monoclinicP21/mspace-group symmetry (No. 11), which arises from conformational changes. The main intramolecular contacts that contribute to the crystal packing in all observed structures are H...H, Halide...H/H...Halide, C...H/H...C, and N...H/H...N. Intramolecular hydrogen bonding between the Zn-bound water and non-Zn-bound pyridyl N atoms is a prominent feature within the three-dimensional networks. Aromatic π-stacking between the non-Zn-bound pyridine rings and contacts involving the halide ligands further stabilize the crystal packing.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/D2QI00443G
