Commentary is given on a paper Butler
(2022).
,
, 364-369 reporting the crystallization of two room-temperature liquids, water and 2,2,6,6-tetra-methyl-piperidine, to form a crystalline solid with a ...water-lined channel potentially capable of proton transport.
The understanding of the hydrogen bond, an interaction that appears in diverse environments and exercises widely varying functions, continues to expand with the report of a neutron diffraction ...analysis of a complex displaying an OH⋅⋅⋅Pt hydrogen bond with unligated water as the donor. What is known about hydrogen bonding so far provides a broad context for this new result.
This educational review postulates the importance of maintaining an adequate level of crystallographic education among structure-dependent scientists whose interests are not primarily in ...crystallography, at a time when automation and validation have made it possible to obtain high-quality structure analyses in many cases with a minimum of crystallographic background. The topics addressed are intended to form a second round of crystallographic education for a novice user whose first round involved hands-on experience with structure solution and an introduction to elementary concepts. The specific topics, chosen for their relevance as basic knowledge and their lack of emphasis in many formal treatments, are (1) crystallographic reference frames and the utility of the reciprocal cell in geometrical calculations; (2) the relationship between the two concepts that constitute our model of the crystal, namely the unit cell and the lattice; (3) the manner in which an atom is represented in concept and in practice; (4) the importance of interleaved symmetry elements required by the presence of additional symmetry on a lattice; (5) the harnessing of the natural properties of the crystalline state for the potential manipulation of properties of synthetic crystals; and (6) useful terminology for navigating a crystal structure.
The reactions of Re(N‐N)(CO)3(PMe3)OTf (N‐N=2,2′‐bipyridine, bipy; 1,10‐phenanthroline, phen) compounds with tBuLi and with LiHBEt3 have been explored. Addition to the N‐N chelate took place with ...different site‐selectivity depending on both chelate and nucleophile. Thus, with tBuLi, an unprecedented addition to C5 of bipy, a regiochemistry not accessible for free bipy, was obtained, whereas coordinated phen underwent tBuLi addition to C2 and C4. Remarkably, when LiHBEt3 reacted with Re(bipy)(CO)3(PMe3)OTf, hydride addition to the 4 and 6 positions of bipy triggered an intermolecular cyclodimerization of two dearomatized pyridyl rings. In contrast, hydride addition to the phen analog resulted in partial reduction of one pyridine ring. The resulting neutral ReI products showed a varied reactivity with HOTf and with MeOTf to yield cationic complexes. These strategies rendered access to ReI complexes containing bipy‐ and phen‐derived chelates with several C(sp3) centers.
Everything is possible with bipy and phen in the game: Post‐coordination functionalization of 2,2′‐bipyridine (bipy) and 1,10‐phenanthroline (phen) has been applied to the synthesis of {ReI(CO)3} complexes containing C(sp3) derivatives of the aromatic chelates. The additions of tBuLi and of LiHBEt3 to Re‐coordinated bipy and phen showed unprecedented site‐selectivity and triggered reaction pathways such as cyclodimerization or reduction.
A new palladium−dipyridylmethylamine complex is an excellent catalyst for C−C bond-forming processes such as the Heck, Suzuki, and Sonogashira reactions in organic and aqueous solvents under ...homogeneous conditions.
The novel nitrosyl-bridged complex W2Cp2(μ-P t Bu2)(μ-κ:η-NO)(CO)(NO)(BAr4) Ar = 3,5-C6H3(CF3)2 was prepared in a multistep procedure starting from the hydride W2Cp2(μ-H)(μ-P t Bu2)(CO)4 and ...involving the new complexes W2Cp2(μ-P t Bu2)(CO)4(BF4), W2Cp2(μ-P t Bu2)(CO)2(NO)2(BAr4), and W2(μ-κ:η5-C5H4)Cp(μ-P t Bu2)(CO)(NO)2 as intermediates, which follow from reactions with HBF4·OEt2, NO, and Me3NO·2H2O, respectively. The nitrosyl-bridged cation easily added chloride upon reaction with N(PPh3)2Cl, with concomitant NO rearrangement into the terminal coordination mode, to give W2ClCp2(μ-P t Bu2)(CO)(NO)2, and underwent N–O and W–W bond cleavages upon the addition of CN t Bu to give the mononuclear phosphinoimido complex WCp(NP t Bu2)(CN t Bu)2(BAr4). Another N–O bond cleavage was induced upon photochemical decarbonylation at 243 K, which gave the oxo- and phosphinito-bridged nitrido complex W2Cp2(N)(μ-O)(μ-OP t Bu2)(NO)(BAr4), likely resulting from a N–O bond cleavage step following decarbonylation.
The involvement of silver in two‐electron AgI/AgIII processes is currently emerging. However, the range of stability of the required and uncommon AgIII species is virtually unknown. Here, the ...stability of AgIII towards the whole set of halide ligands in the organosilver(III) complex frame (CF3)3AgX− (X=F, Cl, Br, I, At) is theoretically analyzed. The results obtained depend on a single factor: the nature of X. Even the softest and least electronegative halides (I and At) are found to form reasonably stable AgIII−X bonds. Our estimates were confirmed by experiment. The whole series of nonradiative halide complexes PPh4(CF3)3AgX (X=F, Cl, Br, I) has been experimentally prepared and all its constituents have been isolated in pure form. The pseudohalides PPh4(CF3)3AgCN and PPh4(CF3)3Ag(N3) have also been isolated, the latter being the first silver(III) azido complex. Except for the iodo compound, all the crystal and molecular structures have been established by single‐crystal X‐ray diffraction methods. The decomposition paths of the (CF3)3AgX− entities at the unimolecular level have been examined in the gas phase by multistage mass spectrometry (MSn). The experimental detection of the two series of mixed complexes CF3AgX− and FAgX− arising from the corresponding parent species (CF3)3AgX− demonstrate that the Ag−X bond is particularly robust. Our experimental observations are rationalized with the aid of theoretical methods. Smooth variation with the electronegativity of X is also observed in the thermolyses of bulk samples. The thermal stability in the solid state gradually decreases from X=F (145 °C, dec.) to X=I (78 °C, dec.) The experimentally established compatibility of AgIII with the heaviest halides is of particular relevance to silver‐mediated or silver‐catalyzed processes.
Unexpectedly robust: We provide theoretical evidence and experimental proof of the unexpected stability of the AgIII−X bond with every halogen (X=F, Cl, Br and I) in the series of square‐planar organosilver(III) derivatives PPh4(CF3)3AgX. Unimolecular decomposition paths were analyzed by combined theoretical and experimental methods, whereby the two series of linear complexes CF3AgX− and FAgX− were detected. The first silver(III) azide was also prepared, isolated and structurally characterized.
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