The cost of a single concussion in American high school football: a retrospective cohort study.

Aim: The potential financial burden of American football-related concussions (FRC) is unknown. Our objective was to describe the healthcare costs associated with an FRC and determine factors associated with increased costs.

Methodology/results: A retrospective cohort study of concussed high school football players presenting between November 2017 and March 2020 was undertaken; 144 male high school football players were included.

Synthesis and Photophysical Properties of T-Shaped Coinage-Metal Complexes.

The photophysical properties of a series of T-shaped coinage d metal complexes, supported by a bis(mesoionic carbene)carbazolide (CNC) pincer ligand, are explored. The series includes a rare new example of a tridentate T-shaped Ag complex. Post-complexation modification of the Au complex provides access to a linear cationic Au complex following ligand alkylation, or the first example of a cationic square planar Au -F complex from electrophilic attack on the metal centre.

Synthesis of heterobimetallic gold(i) ferrocenyl-substituted 1,2,3-triazol-5-ylidene complexes as potential anticancer agents.

1,2,3-Triazol-5-ylidene (trz) complexes of gold(i) containing a ferrocenyl substituent on the C4-position of the trz ring were synthesized to yield the neutral heterobimetallic gold(i) trz chlorido (2), gold(i) trz phenyl (3), and the cationic gold(i) trz triphenylphospine (5) complexes. In order to compare the effect of silver(i) as central metal vs. gold(i), [Ag(trz)2]+ (4) was also prepared, while variation of the C4-1,2,3-triazol-5-ylidene substituent from a ferrocenyl to a phenyl group was done to prepare the monometallic analogue of 5, namely the cationic Au(i) trz triphenylphosphine complex 6.

Mono-, di- and tetrarhenium Fischer carbene complexes with thienothiophene substituents.

The oxidative cleaving of a rhenium-rhenium bond by bromine in binuclear Fischer carbene complexes proves to be an effective method to prepare mononuclear bromido-carbene complexes. The reaction of mono- and dilithiated thieno[2,3-b]thiophene (2,3-b-TTH) and thieno[3,2-b]thiophene (3,2-b-TTH) with [Re(CO)] affords dirhenium nonacarbonyl ethoxycarbene complexes, [Re(CO){C(OEt)2,3-b-TTH}] (1a) and [Re(CO){C(OEt)3,2-b-TTH}] (1b), and the tetrarhenium bis(ethoxycarbene) complexes from the dilithiated thiophene substrates, [Re(CO)-μ-{C(OEt)-2,3-b-TT-C(OEt)}Re(CO)] (2a) and [Re(CO)-μ-{C(OEt)-3,2-b-TT-C(OEt)}Re(CO)] (2b) featuring bridging thiophene linkers. Rhenium-rhenium bond cleavage by bromine of the monocarbene complexes yielded the scarce class of monorhenium bromido-carbene complexes, cis-[Re(CO){C(OEt)2,3-b-TTH}Br] (3a) and cis-[Re(CO){C(OEt)3,2-b-TTH}Br] (3b), while the corresponding reaction of the biscarbene tetrarhenium carbonyl complex of thieno[2,3-b]thiophene afforded the cleaving of both metal-metal bonds to give the novel dirhenium biscarbene dibromido complex with a thienothiophene spacer, [Re(CO)Br-μ-{C(OEt)-2,3-b-TT-C(OEt)}Re(CO)Br] (4a).

A Hemilabile and Cooperative N-Donor-Functionalized 1,2,3-Triazol-5-Ylidene Ligand for Alkyne Hydrothiolation Reactions.

A series of novel cationic and neutral Rh complexes with an N-donor-functionalized 1,2,3-triazol-5-ylidene (TRZ) ligand (in which the pendant N donor is NHBoc, NH , or NMe ) is described. The catalytic activity of these complexes was evaluated in the hydrothiolation of alkynes. Among the catalysts, a neutral dicarbonyl complex featuring the tethered-NBoc amido-TRZ ligand proved very selective for alkyne hydrothiolation with an aryl thiol.

A rhodium(I)-oxygen adduct as a selective catalyst for one-pot sequential alkyne dimerization-hydrothiolation tandem reactions.

An air-stable rhodium(I)-oxygen adduct featuring a CNC-pincer ligand, based on 1,2,3-triazol-5-ylidenes, catalyzes the homo-dimerization and hydrothiolation of alkynes, affording the gem-enyne and α-vinyl sulfide isomers, respectively, with excellent selectivity. A one-pot stepwise strategy allows the selective catalytic preparation of non-symmetric bis-vinyl sulfides, as well as the alkyne dimerization-hydrothiolation tandem reactions.

Synthesis and properties of mono- and dimetal Fischer multicarbene complexes derived from thiophene and thieno[2,3-b]thiophene.

Access to multicarbene complexes of a fused thienothiophene substrate was obtained by the use of the tetrabrominated thieno[2,3-b]thiophene precursor in a lithium-bromide exchange reaction, followed by nucleophilic attack on metal hexacarbonyls (M = Cr, W). Subsequent alkylation afforded unique triscarbene complexes [M(CO)4{{C(OEt)}2C6H1S2C(OEt)}M(CO)5] (M = Cr 12, W 13) featuring three non-equivalent carbene ligands on a single thiophene linker, as well as the bischelated tetracarbene complexes [M(CO)4{{C(OEt)}2C6S2{C(OEt)}2}M(CO)4] (M = Cr 14, W 15). The triscarbene complexes 12 and 13 are the first examples of multi-alkoxycarbene complexes featuring three non-equivalent carbene ligands.

Isolation of a potassium bis(1,2,3-triazol-5-ylidene)carbazolide: a stabilizing pincer ligand for reactive late transition metal complexes.

The synthesis and X-ray crystal structure of a potassium adduct of a monoanionic CNC-pincer ligand featuring two mesoionic carbenes is reported. Owing to the peculiar electronic and steric properties of this ligand, the first neutral stable Ni(II)-hydride, and an unusual Cu(II) complex displaying a seesaw geometry, have been isolated.

Fischer-type gold(I) carbene complexes stabilized by aurophilic interactions.

The synthesis and structure of rare acyclic alkoxy- and aminocarbene complexes of gold(i) are reported, including a novel ferrocenophane dinuclear biscarbene complex. X-Ray diffraction analyses and DFT calculations reveal that these complexes are stabilized by genuine aurophilic interactions.

Substituent effects on the electrochemical, spectroscopic, and structural properties of Fischer mono- and biscarbene complexes of chromium(0).

A series of ten ferrocenyl, furyl, and thienyl mono- and biscarbene chromium(0) complexes were synthesized and characterized spectroscopically and electrochemically. The single crystal structure of the biscarbene complex [(CO)5Cr═C(OEt)-Fu'-(OEt)C═Cr(CO)5] (4a) was determined: C20H12Cr2O13; triclinic; P1; a = 6.2838(5), b = 12.

Electrochemical illumination of thienyl and ferrocenyl chromium(0) Fischer carbene complexes.

A series of ferrocenyl and thienyl mono- and biscarbene chromium(0) complexes 1-6 were synthesised. The complexes were characterised both spectroscopically and electrochemically, and the single crystal X-ray structure of 3 was determined. Electrochemical measurements in CH2Cl2 revealed that the carbene double bond of 1-6 is reduced to an anion radical, (-)Cr-C˙ at formal reduction potentials <-1.

2,2'-(Piperazine-1,4-di-yl)diethanaminium dibenzoate.

The asymmetric unit of the title salt C(8)H(22)N(4) (2+)·2C(7)H(5)O(2) (-), comprises two independent pairs of half a 2,2'-(piperazine-1,4-di-yl)diethanaminium dication plus a benzoate anion. The dications are symmetrical and lie across crystallographic centres of inversion. The crystal structure was refined as a two-component pseudo-merohedral twin using the twin law 001 0-10 100 [he domain fractions are 0.

2,2'-(Piperazine-1,4-di-yl)diethanaminium bis-(2-hy-droxy-benzoate).

The asymmetric unit of the title salt, C(8)H(22)N(4) (2+)·2C(7)H(5)O(3) (-), comprises half a 2,2'-(piperazine-1,4-di-yl)diethan-aminium dication plus a 2-hy-droxy-benzoate anion. In the crystal, the anions and cations are linked by N-H⋯O and O-H⋯O hydrogen bonds to form infinite two-dimensional networks parallel with the a unit-cell face. The conformation adopted by the cation in the crystal is very similar to that adopted by the same cation in the structures of the nitrate and tetra-hydrogen penta-borate salts.

3,6-Diaza-octane-1,8-diaminium diiodide.

The asymmetric unit of the title salt, C(6)H(20)N(4) (2+)·2I(-), comprises half a 3,6-diaza-octane-1,8-diaminium dication plus an I(-) anion. The dications are symmetrical and lie across crystallographic centres of inversion. In the crystal, the ions form a network involving mainly weak N-H⋯I inter-molecular inter-actions: two H atoms of the ammonium group form inter-actions with two I(-) anions and the H atom of the secondary amine forms a weak inter-action with a third I(-) cation.

[N,N'-Bis(2,4,6-trimethyl-phen-yl)ethane-1,2-diimine-κ(2)N,N']tetra-carbonyl-chromium(0).

The octa-hedral coordination of the Cr(0) atom in the title compound, [Cr(C(20)H(24)N(2))(CO)(4)], displays some distortion. This is manifested by an exocyclic torsion angle C(mesitylene)-N-Cr-C(carbon-yl) that deviates by more than 20° from planarity. Another structural feature is the significant distortion from linearity of the Cr-C-O angles of the two carbonyl groups that inter-act with both ortho-methyl groups of the two mesitylene rings.

2-(Biphenyl-4-yl)propan-2-ol.

The title compound, C(15)H(16)O, crystallizes with two independent mol-ecules in the asymmetric unit. Due to the space-group symmetry, this results in the formation of a tetra-mer where the four mol-ecules are connected by O-H⋯O hydrogen bonds. The mol-ecules pack parallel to the c axis.

{μ-5-[1,3-Bis(2,4,6-trimethyl-phen-yl)-3H-imidazolium-2-yl]-2-(2-oxoethenyl-1κC)furan-3-yl-2κC}-μ-hydrido-bis(tetra-carbonyl-rhenium) tetra-hydro-furan 0.67-solvate.

The title complex, [Re(2)(C(27)H(25)N(2)O(2))H(CO)(8)]·0.67C(4)H(8)O, was formed as a product in the reaction of a rhenium(I)-Fischer carbene complex with a free NHC carbene. The coordination environment about the two Re atoms is slightly distorted octahedral, including a bridging H atom.

1,3-Bis(2,4,6-trimethyl-phen-yl)-3H-imidazol-1-ium tetra-oxidorhenate(VII).

The title compound, (C(21)H(25)N(2))[ReO(4)], was formed as the unexpected product in an attempted synthesis of a rhenium(I)-N-heterocyclic carbene (NHC) complex. The compound has crystallographic mirror symmetry with both the cation and the tetrahedral anion located across a mirror plane. The cation and anion are linked by a C-H⋯O hydrogen bond.

Rhenium ethoxy- and hydroxycarbene complexes with thiophene substituents.

Reaction of mono- and dilithiated thiophene (a), bithiophene (b) and 2,5-dibromothiophene (c) with [Re(2)(CO)(10)] afforded, after subsequent alkylation with triethyloxonium tetrafluoroborate, tetra- and binuclear Fischer carbene complexes, [Re(2)(CO)(9){C(OEt){C(4)H(2)S}(n)X}], n = 1, X = H (1a); n = 2, X = H (1b); n = 1, X = Br (1c); n = 1, X = C(OEt)Re(2)(CO)(9), (2a); n = 2, X = C(OEt)Re(2)(CO)(9) (2b), as major products. The dirhenium acylate intermediates from this reaction not only gave the expected novel ethoxycarbene complexes with alkylation but after rhenium-rhenium bond breaking afforded a number of minor products. The (1)H NMR spectrum of the crude reaction mixture revealed the formation of four metal hydride complexes and aldehydes.

Multimetal Fischer carbene complexes of Group VI transition metals: synthesis, structure and substituent effect investigation.

Fischer carbene complexes of tungsten with substituents containing up to two additional different transition metals, with all the metals in electronic contact with the carbene carbon atom, were synthesised and studied both in solution and in the solid state. For the complexes of the type [W(CO)(5){C(OR')R}], the substituents chosen were heteroaromatic 2-benzo[b]thienyl (2-BT), or 2-BT π-bonded to a chromium tricarbonyl fragment ([Cr(CO)(3)(2-η(6)-BT)]) or ferrocenyl (Fc) as the R-substituent, while the OR'-substituent was systematically varied between an ethoxy or a titanoxy group, to yield the complexes 1b (R' = Et, R = 2-BT), 2b (R' = Et, R = [Cr(CO)(3)(2-η(6)-BT)]), 3b (R' = TiCp(2)Cl, R = 21-BT), 4b (R' = TiCp(2)Cl, R = [Cr(CO)(3)(2-η(6)-BT)]), 5b (R' = Et, R = Fc) and 6b (R' = TiCp(2)Cl, R = Fc). The structural features and their relevance to bonding in the multimetal carbene compounds of both these tungsten and the analogous chromium complexes were investigated as they represent indicators of possible reactivity sites in multimetal carbene assemblies.

Synthesis, characterization, and structural studies of multimetallic ferrocenyl carbene complexes of group VII transition metals.

Fischer carbene complexes of the group VII transition metals (Mn and Re) containing at least two or three different transition metal substituents, all in electronic contact with the carbene carbon atom, were synthesized. The structural features and their relevance to bonding in the carbene multimetal compounds were investigated, as they represent indicators of possible reactivity sites in polymetallic carbene assemblies. For complexes of the type [ML(x){C(OR)R'}] (ML(x) = MnCp(CO)(2) or Re(2)(CO)(9)), ferrocenyl (Fc) was chosen as the R' substituent, while the OR substituent was systematically varied between an ethoxy or a titanoxy group, to yield the complexes 1a (ML(x) = MnCp(CO)(2), R = Et, R' = Fc), 2a (ML(x) = MnCp(CO)(2), R = TiCp(2)Cl, R' = Fc), 3a (ML(x) = Re(2)(CO)(9), R = Et, R' = Fc), and 4a (ML(x) = Re(2)(CO)(9), R = TiCp(2)Cl, R' = Fc).

Thiophene decorated with Fischer carbene ligands.

The activation of a section, or of all the carbons of thiophene by bromine in lithium-halogen exchange reactions, was implemented in a step-wise manner to facilitate the preparation of novel multiple Fischer carbene-bearing thiophene compounds.

Bis(4-amino-benzoic acid-κN)dichloridozinc(II).

Mol-ecules of the title compound [ZnCl(2)(C(7)H(7)NO(2))(2)], are located on a twofold rotation axis. Two 4-amino-benzoic acid moieties, and two chloride ligands are coordinated to a Zn atom in a tetra-hedral fashion, forming an isolated mol-ecule. Neighbouring mol-ecules are linked through hydrogen-bonded carboxyl groups, as well as N-H⋯Cl hydrogen-bonding inter-actions between amine groups and the chloride ligands of neighbouring mol-ecules, forming a three-dimensional network.

3-Methyl-anilinium nitrate.

In the title compound, C(7)H(10)N(+)·NO(3) (-), the 3-methyl-anilinium cations inter-act with the nitrate anions through strong bifurcated N(+)-H⋯(O,O) hydrogen bonds, forming a two-dimensional hydrogen-bonded network.