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1. H ₂ evolution from H ₂ O via O–H oxidative addition across a 9,10-diboraanthracene

   https://doi.org/10.1039/D0CC05261B  

   Taylor, Jordan W.; Harman, W. Hill (November 2020, Chemical Communications)

   null (Ed.)

   The water reactivity of the boroauride complex ([Au(B 2 P 2 )][K(18-c-6)]; (B 2 P 2 , 9,10-bis(2-(diisopropylphosphino)-phenyl)-9,10-dihydroboranthrene) and its corresponding two-electron oxidized complex, Au(B 2 P 2 )Cl, are presented. Au(B 2 P 2 )Cl is tolerant to H 2 O and forms the hydroxide complex Au(B 2 P 2 )OH in the presence of H 2 O and triethylamine. [Au(B 2 P 2 )]Cl and [Au(B 2 P 2 )]OH are poor Lewis acids as judged by the Gutmann–Becket method, with [Au(B 2 P 2 )]OH displaying facile hydroxide exchange between B atoms of the DBA ring as evidenced by variable temperature NMR spectroscopy. The reduced boroauride complex [Au(B 2 P 2 )] − reacts with 1 equivalent of H 2 O to produce a hydride/hydroxide product, [Au(B 2 P 2 )(H)(OH)] − , that rapidly evolves H 2 upon further H 2 O reaction to yield the dihydroxide compound, [Au(B 2 P 2 )(OH) 2 ] − . [Au(B 2 P 2 )]Cl can be regenerated from [Au(B 2 P 2 )(OH) 2 ] − via HCl·Et 2 O, providing a synthetic cycle for H 2 evolution from H 2 O enabled by O–H oxidative addition at a diboraanthracene unit. 

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2. Synthesis, characterization, and alkoxide transfer reactivity of dimeric Tl ₂ (OR) ₂ complexes

   https://doi.org/10.1039/d0dt03917a  

   Grass, Amanda; Kulathungage, Lakshani Wathsala; Wannipurage, Duleeka; Yousif, Maryam; Ward, Cassandra L.; Groysman, Stanislav (February 2021, Dalton Transactions)

   null (Ed.)

   Reaction of LiOC t Bu 2 Ph with TlPF 6 forms the dimeric Tl 2 (OC t Bu 2 Ph) 2 complex, a rare example of a homoleptic thallium alkoxide complex demonstrating formally two-coordinate metal centers. Characterization of Tl 2 (OC t Bu 2 Ph) 2 by 1 H and 13 C NMR spectroscopy and X-ray crystallography reveals the presence of two isomers differing by the mutual conformation of the alkoxide ligands, and by the planarity of the central Tl–O–Tl–O plane. Tl 2 (OC t Bu 2 Ph) 2 serves as a convenient precursor to the formation of old and new [M(OC t Bu 2 Ph) n ] complexes (M = Cr, Fe, Cu, Zn), including a rare example of T-shaped Zn(OC t Bu 2 Ph) 2 (THF) complex, which could not be previously synthesized using more conventional LiOR/HOR precursors. The reaction of [Ru(cymene)Cl 2 ] 2 with Tl 2 (OC t Bu 2 Ph) 2 results in the formation of a ruthenium( ii ) alkoxide complex. For ruthenium, the initial coordination of the alkoxide triggers C–H activation at the ortho -H of [OC t Bu 2 Ph] which results in its bidentate coordination. In addition to Tl 2 (OC t Bu 2 Ph) 2 , related Tl 2 (OC t Bu 2 (3,5-Me 2 C 6 H 3 )) 2 was also synthesized, characterized, and shown to exhibit similar reactivity with iron and ruthenium precursors. Synthetic, structural, and spectroscopic characterizations are presented. 

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3. Towards accurate prediction for laser-coolable molecules: relativistic coupled-cluster calculations for yttrium monoxide and prospects for improving its laser cooling efficiencies

   https://doi.org/10.1039/D0CP04608F  

   Zhang, Chaoqun; Korslund, Hannah; Wu, Yewei; Ding, Shiqian; Cheng, Lan (November 2020, Physical Chemistry Chemical Physics)

   null (Ed.)

   Benchmark relativistic coupled-cluster calculations for yttrium monoxide (YO) with accurate treatment of relativistic and electron correlation effects are reported. The spin–orbit mixing of 2 Π and 2 Δ is found to be an order of magnitude smaller than previously reported in the literature. Together with the measurement of the lifetime of the A′ 2 Δ 3/2 state, it implies an enhanced capability of a narrow-line cooling scheme to bring YO to sub-recoil temperature. The computed electronic transition properties also support a four-photon scheme to close the leakage of the A 2 Π 1/2 ↔ X 2 Σ 1/2 + cycle through the A′ 2 Δ 3/2 state by repumping the A′ 2 Δ 3/2 state to the B 2 Σ 1/2 + state, which subsequently decays back to X 2 Σ 1/2 + . Relativistic coupled-cluster methods, capable of providing accurate spectroscopic parameters that characterize the local potential curves and hence of providing accurate Franck–Condon factors, appear to be promising candidates for accurate calculation of properties for laser-coolable molecules. 

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4. Crystal structures of two new six-coordinate iron(III) complexes with 1,2-bis(diphenylphosphane) ligands

   https://doi.org/10.1107/S2056989018006898  

   McNeil, Derek L.; Beckford, Daihlia J.; Kneebone, Jared L.; Carpenter, Stephanie H.; Brennessel, William W.; Neidig, Michael L. (June 2018, Acta Crystallographica Section E Crystallographic Communications)

   Structural characterization of the ionic complexes [FeCl 2 (C 26 H 22 P 2 ) 2 ][FeCl 4 ]·0.59CH 2 Cl 2 or [(dppen) 2 FeCl 2 ][FeCl 4 ]·0.59CH 2 Cl 2 (dppen = cis -1,2-bis(diphenylphosphane)ethylene, P 2 C 26 H 22 ) and [FeCl 2 (C 30 H 24 P 2 ) 2 ][FeCl 4 ]·CH 2 Cl 2 or [(dpbz) 2 FeCl 2 ][FeCl 4 ]·CH 2 Cl 2 (dpbz = 1,2-bis(diphenylphosphane)benzene, P 2 C 30 H 24 ) demonstrates trans coordination of two bidentate phosphane ligands (bisphosphanes) to a single iron(III) center, resulting in six-coordinate cationic complexes that are balanced in charge by tetrachloridoferrate(III) monoanions. The trans bisphosphane coordination is consistent will all previously reported molecular structures of six coordinate iron(III) complex cations with a (PP) 2 X 2 ( X = halido) donor set. The complex with dppen crystallizes in the centrosymmetric space group C 2/ c as a partial-occupancy [0.592 (4)] dichloromethane solvate, while the dpbz-ligated complex crystallizes in the triclinic space group P 1 as a full dichloromethane monosolvate. Furthermore, the crystal studied of [(dpbz) 2 FeCl 2 ][FeCl 4 ]·CH 2 Cl 2 was an inversion twin, whose component mass ratio refined to 0.76 (3):0.24 (3). Beyond a few very weak C—H...Cl and C—H...π interactions, there are no significant supramolecular features in either structure. 

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5. Higher spin states in some low-energy bis(tetramethyl-1,2-diaza-3,5-diborolyl) sandwich compounds of the first row transition metals: boraza analogues of the metallocenes

   https://doi.org/10.1039/C8NJ05517C  

   Chen, Jianlin; Feng, Hao; Xie, Yaoming; King, R. Bruce; Schaefer, Henry F. (March 2019, New Journal of Chemistry)

   The known sandwich compound [η 5 -(CH 2 ) 3 N 2 (BPh) 2 CMe] 2 Fe in which adjacent C 2 units are replaced by isoelectronic BN units can be considered as a boraza analogues of ferrocene similar to borazine, B 3 N 3 H 6 , considered as a boraza analogue of benzene. In this connection, the related bis(1,2,3,5-tetramethyl-1,2-diaza-3,5-diborolyl) derivatives (Me 4 B 2 N 2 CH) 2 M (M = Ti, V, Cr, Mn, Fe, Co, Ni) for all of the first row transition metals have been optimized using density functional theory for comparison with the isoelectronic tetramethylcyclopentadienyl derivatives (Me 4 C 5 H) 2 M. Low-energy sandwich structures having parallel B 2 N 2 C rings in a trans orientation are found for all seven metals. The 1,2-diaza-3,5-diborolyl ligand appears to be a weaker field ligand than the isoelectronic cyclopentadienyl ligand as indicated by higher spin ground states for some (η 5 -Me 4 B 2 N 2 CH) 2 M sandwich compounds relative to the corresponding metallocenes (η 5 -Me 4 C 5 H) 2 M. Thus (η 5 -Me 4 B 2 N 2 CH) 2 Cr has a quintet ground state in contrast to the triplet ground state of (η 5 -Me 4 C 5 H) 2 Cr. Similarly, the sextet ground state of (η 5 -Me 4 B 2 N 2 CH) 2 Mn lies ∼18 kcal mol −1 below the quartet state in contrast to the doublet ground state of the isoelectronic (Me 4 C 5 H) 2 Mn. These sandwich compounds are potentially accessible by reaction of 1,2-diaza-3,5-diborolide anions with metal halides analogous to the synthesis of [η 5 -(CH 2 ) 3 N 2 (BPh) 2 CMe] 2 Fe. 

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