Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Robust dicopper(I) µ-boryl complexes supported by a dinucleating naphthyridine-based ligand

Copper boryl species have been widely invoked as reactive intermediates in Cu-catalysed C−H borylation reactions, but their isolation and study have been challenging. Use of the robust dinucleating ligand DPFN (2,7-bis(fluoro-di(2-pyridyl)methyl)-1,8-naphthyridine) allowed for the isolation of two very thermally stable dicopper(I) boryl complexes, [(DPFN)Cu2(µ-Bpin)][NTf2] (2) and [(DPFN)Cu2(µ-Bcat)][NTf2] (4) (pin = 2,3-dimethylbutane-2,3-diol; cat = benzene-1,2-diol). These complexes were prepared by cleavage of the corresponding diborane via reaction with the alkoxide [(DPFN)Cu2(µ-OtBu)][NTf2] (3). Reactivity studies illustrated the exceptional stability of these boryl complexes (thermal stability in solution up to 100 °C) and their role in the activation of C(sp)−H bonds. X-ray diffraction and computational studies provide a detailed description of the bonding and electronic structures in these species, and suggest that the dinucleating character of the naphthyridine-based ligand is largely responsible for their remarkable stability

Effects of Coordinating a Hemilabile Ligand to 14e Cp*M(NO) Scaffolds (M = Mo, W)

This article describes the differing chemical properties imparted by the two ligands, hemilabile 2-[(diisopropylphosphino)­methyl]-3-methylpyridine (ⁱPr₂PN) and the related 1,2-bis­(dimethylphosphino)­ethane (dmpe), when attached to the 14e Cp*M­(NO) scaffolds (Cp* = η⁵-C₅Me₅; M = W, Mo). For instance, the treatment of [Cp*W­(NO)­Cl₂]₂ with 2 or 1 equiv of dmpe in C₆H₆ affords excellent yields of [Cp*W­(NO)­(κ²-dmpe)­Cl]Cl (<b>1</b>) or [Cp*W­(NO)­Cl₂]₂[μ-dmpe] (<b>2</b>). In contrast, the treatment of [Cp*W­(NO)­Cl₂]₂ with 1 equiv of ⁱPr₂PN in C₆H₆ does not produce the complex analogous to <b>1</b> but rather affords orange [Cp*W­(NO)­(κ²-P-N-ⁱPr₂PN)­Cl]­[Cp*W­(NO)­Cl₃] (<b>3</b>) in 90% yield. Furthermore, subsequent reduction of <b>1</b> or <b>2</b> with 2 or 4 equiv of Cp₂Co in tetrahydrofuran (THF), respectively, results in the production of orange Cp*W­(NO)­(κ²-dmpe) (<b>4</b>) in good yields. However, a similar treatment of <b>3</b> with 1 equiv of Cp₂Co in THF does not result in the production of Cp*W­(NO)­(κ²-P,N-ⁱPr₂PN), the analogue of <b>4</b>, but rather generates a 1:1 mixture of the novel complexes Cp*W­(NO)­(H)­(κ¹-P-ⁱPr₂PN)Cl (<b>5</b>) and Cp*W­(NO)­(κ²-P,N-ⁱPr₂PCH-2-(3-Me-C₅H₃N))Cl (<b>6</b>), which are separable by crystallization from pentane and diethyl ether solutions, respectively. The divergent reactivity imparted by the dmpe and ⁱPr₂PN proligands is a unique demonstration of the unusual properties of a mixed-donor ligand. In the case of molybdenum, the reaction of [Cp*Mo­(NO)­Cl₂]₂ with 2 equiv of ⁱPr₂PN in C₆H₆ first forms Cp*Mo­(NO)­(κ¹-P-ⁱPr₂PN)­Cl₂, which then converts to [Cp*Mo­(NO)­(κ²-P,N-ⁱPr₂PN)­Cl]­[Cp*Mo­(NO)­Cl₃], the analogue of <b>3</b>. Reduction of the Cp*Mo­(NO)­(κ¹-P-ⁱPr₂PN)­Cl₂ intermediate complex with 2 equiv of Cp₂Co affords dark-green Cp*Mo­(NO)­(κ²-P,N-ⁱPr₂PN) (<b>7</b>). All new complexes have been characterized by conventional spectroscopic and analytical methods, and the solid-state molecular structures of most of them have been established by single-crystal X-ray crystallographic analyses

Tetracopper σ‐Bound μ‐Acetylide and ‐Diyne Units Stabilized by a Naphthyridine‐based Dinucleating Ligand

Reactions of a dicopper(I) tert-butoxide complex with alkynes possessing boryl or silyl capping groups resulted in formation of unprecedented tetracopper(I) μ-acetylide/diyne complexes that were characterized by NMR and UV/Vis spectroscopy, mass spectrometry and single-crystal X-ray diffraction. These compounds possess an unusual μ4 -η1 :η1 :η1 :η1 coordination mode for the bridging organic fragment, enforced by the rigid and dinucleating nature of the ligand utilized. Thus, the central π system remains unperturbed and accessible for subsequent reactivity and modification. This has been corroborated by addition of a fifth copper atom, giving rise to a pentacopper acetylide complex. This work may provide a new approach by which metal-metal cooperativity can be exploited in the transformation of acetylide and diyne groups to a variety of substrates, or as a starting point for the controlled synthesis of copper(I) alkyne-containing clusters

Robust dicopper(i) μ-boryl complexes supported by a dinucleating naphthyridine-based ligand.

Copper boryl species have been widely invoked as reactive intermediates in Cu-catalysed C-H borylation reactions, but their isolation and study have been challenging. Use of the robust dinucleating ligand DPFN (2,7-bis(fluoro-di(2-pyridyl)methyl)-1,8-naphthyridine) allowed for the isolation of two very thermally stable dicopper(i) boryl complexes, [(DPFN)Cu2(μ-Bpin)][NTf2] (2) and [(DPFN)Cu2(μ-Bcat)][NTf2] (4) (pin = 2,3-dimethylbutane-2,3-diol; cat = benzene-1,2-diol). These complexes were prepared by cleavage of the corresponding diborane via reaction with the alkoxide [(DPFN)Cu2(μ-O t Bu)][NTf2] (3). Reactivity studies illustrated the exceptional stability of these boryl complexes (thermal stability in solution up to 100 °C) and their role in the activation of C(sp)-H bonds. X-ray diffraction and computational studies provide a detailed description of the bonding and electronic structures in these complexes, and suggest that the dinucleating character of the naphthyridine-based ligand is largely responsible for their remarkable stability

Direct Transformation of SiH4 to a Molecular L(H)2CoSiCo(H)2L Silicide Complex

The synthesis of bimetallic molecular silicide complexes is reported, based on the use of multiple Si-H bond activations in SiH4 at the metal centers of 14-electron LCoI fragments (L = Tp″, HB(3,5-diisopropylpyrazolyl)3-; [BP2tBuPz], PhB(CH2PtBu2)2(pyrazolyl)). Upon exposure of (Tp″Co)2(μ-N2) (1) to SiH4, a mixture of (Tp″Co)2(μ-H) (2) and (Tp″Co)2(μ-H)2 (3) was formed and no evidence for Si-H oxidative addition products was observed. In contrast, [BP2tBuPz]-supported Co complexes led to Si-H oxidative additions with the generation of silylene and silicide complexes as products. Notably, the reaction of ([BP2tBuPz]Co)2(μ-N2) (5) with SiH4 gave the dicobalt silicide complex [BP2tBuPz](H)2Co═Si═Co(H)2[BP2tBuPz] (8) in high yield, representing the first direct route to a symmetrical bimetallic silicide. The effect of the [BP2tBuPz] ligand on Co-Si bonding in 7 and 8 was explored by analysis of solid-state molecular structures and density functional theory (DFT) investigations. Upon exposure to CO or DMAP (DMAP = 4-dimethylaminopyridine), 8 converted to the corresponding [BP2tBuPz]Co(L)x adducts (L = CO, x = 2; L = DMAP, x = 1) with concomitant loss of SiH4, despite the lack of significant Si-H interactions in the starting complex. On heating to 60 °C, 8 underwent reaction with MeCl to produce small quantities of MexSiH4-x (x = 1-3), demonstrating functionalization of the μ-silicon atom in a molecular silicide to form organosilanes

Cationic and Neutral Cp*M(NO)(κ²‑Ph₂PCH₂CH₂PPh₂) Complexes of Molybdenum and Tungsten: Lewis-Acid-Induced Intramolecular C–H Activation

Treatment of CH₂Cl₂ solutions of Cp*M­(NO)­Cl₂ (Cp* = η⁵-C₅(CH₃)₅; M = Mo, W) first with 2 equiv of AgSbF₆ in the presence of PhCN and then with 1 equiv of Ph₂PCH₂CH₂PPh₂ affords the yellow–orange salts [Cp*M­(NO)­(PhCN)­(κ²-Ph₂PCH₂CH₂PPh₂)]­(SbF₆)₂ in good yields (M = Mo, W). Reduction of [Cp*M­(NO)­(PhCN)­(κ²-Ph₂PCH₂CH₂PPh₂)]­(SbF₆)₂ with 2 equiv of Cp₂Co in C₆H₆ at 80 °C produces the corresponding 18e neutral compounds, Cp*M­(NO)­(κ²-Ph₂PCH₂CH₂PPh₂) which have been isolated as analytically pure orange–red solids. The addition of 1 equiv of the Lewis acid, Sc­(OTf)₃, to solutions of Cp*M­(NO)­(κ²-Ph₂PCH₂CH₂PPh₂) at room temperature results in the immediate formation of thermally stable Cp*M­(NO→Sc­(OTf)₃)­(H)­(κ³-(C₆H₄)­PhPCH₂CH₂PPh₂) complexes in which one of the phenyl substituents of the Ph₂PCH₂CH₂PPh₂ ligands has undergone intramolecular orthometalation. In a similar manner, addition of BF₃ produces the analogous Cp*M­(NO→BF₃)­(H)­(κ³-(C₆H₄)­PhPCH₂CH₂PPh₂) complexes. In contrast, B­(C₆F₅)₃ forms the 1:1 Lewis acid–base adducts, Cp*M­(NO→B­(C₆F₅)₃)­(κ²-Ph₂PCH₂CH₂PPh₂) in CH₂Cl₂ at room temperature. Upon warming to 80 °C, Cp*Mo­(NO→B­(C₆F₅)₃)­(κ²-Ph₂PCH₂CH₂PPh₂) converts cleanly to the orthometalated product Cp*Mo­(NO→B­(C₆F₅)₃)­(H)­(κ³-(C₆H₄)­PhPCH₂CH₂PPh₂), but Cp*W­(NO→B­(C₆F₅)₃)­(κ²-Ph₂PCH₂CH₂PPh₂) generates a mixture of products whose identities remain to be ascertained. Attempts to extend this chemistry to include related Ph₂PCH₂PPh₂ compounds have had only limited success. All new complexes have been characterized by conventional spectroscopic and analytical methods, and the solid-state molecular structures of most of them have been established by single-crystal X-ray crystallographic analyses

A sequential cyclization/π-extension strategy for modular construction of nanographenes enabled by stannole cycloadditions.

The synthesis of polycyclic aromatic hydrocarbons (PAHs) and related nanographenes requires the selective and efficient fusion of multiple aromatic rings. For this purpose, the Diels-Alder cycloaddition has proven especially useful; however, this approach currently faces significant limitations, including the lack of versatile strategies to access annulated dienes, the instability of the most commonly used dienes, and difficulties with aromatization of the [4 + 2] adduct. In this report we address these limitations via the marriage of two powerful cycloaddition strategies. First, a formal Cp2Zr-mediated [2 + 2 + 1] cycloaddition is used to generate a stannole-annulated PAH. Secondly, the stannoles are employed as diene components in a [4 + 2] cycloaddition/aromatization cascade with an aryne, enabling π-extension to afford a larger PAH. This discovery of stannoles as highly reactive - yet stable for handling - diene equivalents, and the development of a modular strategy for their synthesis, should significantly extend the structural scope of PAHs accessible by a [4 + 2] cycloaddition approach

Isolation and Study of Ruthenium-Cobalt Oxo Cubanes Bearing a High-Valent, Terminal RuV-Oxo with Significant Oxyl Radical Character.

High-valent RuV-oxo intermediates have long been proposed in catalytic oxidation chemistry, but investigations into their electronic and chemical properties have been limited due to their reactive nature and rarity. The incorporation of Ru into the [Co3O4] subcluster via the single-step assembly reaction of CoII(OAc)2(H2O)4 (OAc = acetate), perruthenate (RuO4-), and pyridine (py) yielded an unprecedented Ru(O)Co3(μ3-O)4(OAc)4(py)3 cubane featuring an isolable, yet reactive, RuV-oxo moiety. EPR, ENDOR, and DFT studies reveal a valence-localized [RuV(S = 1/2)CoIII3(S = 0)O4] configuration and non-negligible covalency in the cubane core. Significant oxyl radical character in the RuV-oxo unit is experimentally demonstrated by radical coupling reactions between the oxo cubane and both 2,4,6-tri-tert-butylphenoxyl and trityl radicals. The oxo cubane oxidizes organic substrates and, notably, reacts with water to form an isolable μ-oxo bis-cubane complex [(py)3(OAc)4Co3(μ3-O)4Ru]-O-[RuCo3(μ3-O)4(OAc)4(py)3]. Redox activity of the RuV-oxo fragment is easily tuned by the electron-donating ability of the distal pyridyl ligand set at the Co sites demonstrating strong electronic communication throughout the entire cubane cluster. Natural bond orbital calculations reveal cooperative orbital interactions of the [Co3O4] unit in supporting the RuV-oxo moiety via a strong π-electron donation

Thermal Chemistry of Cp*W(NO)(CH₂CMe₃)(H)(L) Complexes (L = Lewis Base)

The complexes <i>trans</i>-Cp*W­(NO)­(CH₂CMe₃)­(H)­(L) (Cp* = η⁵-C₅Me₅) result from the treatment of Cp*W­(NO)­(CH₂CMe₃)₂ in <i>n</i>-pentane with H₂ (∼1 atm) in the presence of a Lewis base, L. The designation of a particular geometrical isomer as <i>cis</i> or <i>trans</i> indicates the relative positions of the alkyl and hydrido ligands in the base of a four-legged piano-stool molecular structure. The thermal behavior of these complexes is markedly dependent on the nature of L. Some of them can be isolated at ambient temperatures [e.g., L = P­(OMe)₃, P­(OPh)₃, or P­(OCH₂)₃CMe]. Others undergo reductive elimination of CMe₄ via <i>trans</i> to <i>cis</i> isomerization to generate the 16e reactive intermediates Cp*W­(NO)­(L). These intermediates can intramolecularly activate a C–H bond of L to form 18e <i>cis</i> complexes that may convert to the thermodynamically more stable <i>trans</i> isomers [e.g., Cp*W­(NO)­(PPh₃) initially forms <i>cis</i>-Cp*W­(NO)­(H)­(κ²-PPh₂­C₆H₄) that upon being warmed in <i>n</i>-pentane at 80 °C isomerizes to <i>trans</i>-Cp*W­(NO)­(H)­(κ²-PPh₂­C₆H₄)]. Alternatively, the Cp*W­(NO)­(L) intermediates can effect the intermolecular activation of a substrate R-H to form <i>trans</i>-Cp*W­(NO)­(R)­(H)­(L) complexes [e.g., L = P­(OMe)₃ or P­(OCH₂)₃CMe; R-H = C₆H₆ or Me₄Si] probably via their <i>cis</i> isomers. These latter activations are also accompanied by the formation of some Cp*W­(NO)­(L)₂ disproportionation products. An added complication in the L = P­(OMe)₃ system is that thermolysis of <i>trans</i>-Cp*W­(NO)­(CH₂CMe₃)­(H)­(P­(OMe)₃) results in it undergoing an Arbuzov-like rearrangement and being converted mainly into [Cp*W­(NO)­(Me)­(PO­(OMe)₂)]₂, which exists as a mixture of two isomers. All new complexes have been characterized by conventional and spectroscopic methods, and the solid-state molecular structures of most of them have been established by single-crystal X-ray crystallographic analyses