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1.
J Neonatal Perinatal Med ; 17(1): 133-136, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38277305

RESUMO

Choledochal cysts (CC) are congenital biliary tract dilatations. Infantile CC (IFCC) in very low birth weight (VLBW) infants is rare. This is a case of a huge IFCC presented in VLBW preterm infant managed with external biliary drainage prior to definitive treatment. Electrolyte imbalance, poor weight gain, and infections were managed during external biliary drainage maintenance. Choledochal cyst excision and Roux-en-Y hepaticoenterostomy were successfully performed when the infant weighed 4.9 kg 5 months later. Delayed definitive treatment with external biliary drainage could be a feasible alternative for managing CC in low-birth-weight infants.


Assuntos
Sistema Biliar , Cisto do Colédoco , Humanos , Recém-Nascido , Cisto do Colédoco/cirurgia , Drenagem , Recém-Nascido Prematuro , Recém-Nascido de muito Baixo Peso
2.
Clin Case Rep ; 11(12): e8240, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-38033678

RESUMO

Staphylococcal scalded skin syndrome (SSSS) is a rare condition in premature infants. We report a case of SSSS in a preterm neonate who displayed all clinical manifestations at birth, leading to a fatal outcome from Candida parapsilosis fungemia. The clinical presentation was challenging to differential diagnosis. SSSS diagnosis was confirmed by skin biopsy. This case emphasizes the significance of early recognition and diagnosis of SSSS promptly for clinicians. Congenital SSSS in premature infants can be fatal, but with early recognition and appropriate supportive and antimicrobial therapy, outcomes can be improved and lives can be saved.

3.
Fish Shellfish Immunol ; 139: 108882, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37279829

RESUMO

The efficacy of postbiotics on the immune-related gene expression and gut microbiota of white shrimp, Penaeus vannamei remains unexplored. A commercial heat-killed postbiotic Pediococcus pentosaceus PP4012 was used to evaluate the growth performance, intestinal morphology, immunological status, and microbial community of white shrimp after dietary administration in this study. White shrimp (0.040 ± 0.003 g) were divided into three treatments; a control, inanimate P. pentosaceus (105 CFU g feed-1) at low concentration (IPL) and inanimate P. pentosaceus (106 CFU g feed-1) at high concentrations (IPH). The diets of IPL and IPH significantly increased final weight, specific growth rate and production compared to the control group. Shrimp fed with IPL and IPH significantly utilized feed more efficiently than those fed the control diet. The IPH treatment significantly lowered the cumulative mortality rate compared to the control and IPL diet following Vibrio parahaemolyticus infection. No significant difference was observed for Vibrio-like and lactic acid bacteria in intestine of shrimp fed with the control diet and the experimental diets. Adding inanimate P. pentosaceus significantly improved immune responses such as lysozyme and phagocytic activity compared to the control group. However, the total hemocyte count, phenoloxidase activity, respiratory burst, and superoxide dismutase activity were not significantly different among treatments. The immune-related genes alf, pen3a, and pen4 expression were significantly higher in shrimp fed IPL diet compared with control and IPH. Taxonomic identification of bacterial genera in all dietary groups belonged to two predominant phyla, Proteobacteria and Bacteroidota. An abundance of Photobacterium, Motilimonas, Litorilituus, and Firmicutes bacterium ZOR0006 were identified in the intestine of shrimp fed postbiotic diets. Unique microbes such as Cohaesibacter was discovered in the shrimp fed IPL while Candidatus Campbellbacteria, uncultured Verrucomicrobium DEV114 and Paenalcaligenes were discovered in the intestines of shrimp fed IPH diet. Collectively, these data suggest that including heat-killed P. pentosaceus, particularly IPH, can enhance growth performance, promote microbial diversity, elevate immune responses, and increase shrimp's resistance to V. parahaemolyticus.


Assuntos
Microbioma Gastrointestinal , Penaeidae , Animais , Pediococcus pentosaceus , Imunidade Inata , Temperatura Alta , Dieta/veterinária , Ração Animal/análise , Suplementos Nutricionais/análise
4.
Nanomaterials (Basel) ; 12(24)2022 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-36558220

RESUMO

In this study, we proposed a novel CoIn2S4/reduced graphene oxide (CoIn2S4/rGO) composite anode using a hydrothermal method. By introducing electronic-conductive reduced graphene oxide (rGO) to buffer the extreme volume expansion of CoIn2S4, we prevented its polysulfide dissolution during the lithiation/de-lithiation processes. After 100 cycles, the pristine CoIn2S4 electrode demonstrated poor cycle performance of only 120 mAh/g at a current density of 0.1 A/g. However, the composition-optimized CoIn2S4/rGO composite anode demonstrated a reversible capacity of 580 mAh/g for 100 cycles, which was an improvement of 4.83 times. In addition, the ex situ XRD measurements of the CoIn2S4/rGO electrode were conducted to determine the reaction mechanism and electrochemical behavior. These results suggest that the as-synthesized CoIn2S4/rGO composite anode is a promising anode material for lithium ion batteries.

5.
Int J Gen Med ; 15: 4657-4664, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35548587

RESUMO

Purpose: During the coronavirus disease 2019 (COVID-19) pandemic, visits to emergency department (ED) have significantly declined worldwide. The purpose of this study was to identify the trend of visits to ED for different diseases at the peak and slack stages of the epidemic. Patients and Methods: This was a retrospective observational study conducted in a tertiary referral medical center in northern Taiwan. We recorded weekly ED visits for myocardial infarction with or without ST-elevation (STEMI or NSTEMI), out-of-hospital cardiac arrest (OHCA), acute stroke, and congestive heart failure from 2016 to 2021. We compared the local epidemic peak periods (calendar weeks 4-18, 2020 and calendar weeks 21-31, 2021) and its corresponding slack periods (calendar weeks 4-18, 2021 and calendar weeks 21-31, 2020) with the baseline period (2016-2019) using Mann-Whitney test to identify the difference. Results: We observed a significant decline in ED visits (median [Q1, Q3]) during the epidemic for OHCA (6 [5, 7] and 5 [4, 6], p = 0.046, for baseline and peak period, respectively, in week 4-18), acute stroke (41.5 [38, 47] and 35 [28, 39], p < 0.001, in week 4-18, 40 [35, 45] and 35 [28, 40], p = 0.039, in week 21-31) and CHF (28 [24.25, 33] and 19 [12, 23], p < 0.001, in week 4-18, 18 [16, 23] and 13 [11, 16], p = 0.001, in week 21-31). Significant difference was not observed in patients with NSTEMI and STEMI in both week 4-18 and 21-31, and cardiac arrest in week 21-31. There was a rebound in ED visits in the slack period. Conclusion: This study revealed that ED visits significantly declined during the COVID-19 epidemic and rebounded in the slack period. The trend was significant for acute stroke and heart failure but was relatively less prominent effect for emergent events such as cardiac arrest or myocardial infarction.

6.
ACS Omega ; 6(4): 2836-2845, 2021 Feb 02.
Artigo em Inglês | MEDLINE | ID: mdl-33553901

RESUMO

In this study, inorganic perovskite (CsPbBr3) quantum dots are wrapped in SiO2 to provide better performance against external erosion. Long-term storage (250 days) is demonstrated with very little changes in the illumination capability of these quantum dots. While in the continuous aging procedure, different package architectures can achieve very different lifetimes. As long as 6000 h of lifetime can be expected from these quantum dots, but the blue shift of emission wavelength still needs more investigation.

7.
PLoS One ; 13(4): e0194866, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29641608

RESUMO

Zearalenone (ZEN) is a mycotoxin produced by Fusarium species, which is one of the main animal feed contaminants causing reproductive disorders in livestock. The aim of this study was to evaluate the probiotic characteristics and ZEN removal ability of a Bacillus licheniformis strain CK1. The probiotic properties, including acidic tolerance, bile salt tolerance, adherence capability, and anti-pathogenic activities of CK1 were evaluated. CK1 survived after incubation at pH 2.0 or 3.0 for 3 h, grew well in LB broth containing 0.3% oxgall, possessed adherence capability to Caco-2 cells, and inhibited the growth of Escherichia coli O157:H7 and Listeria monocytogenes. The ZEN removal ability of CK1 was compared with a mineral mycotoxin-adsorbing agent, hydrated sodium calcium aluminosilicate (HSCAS), and a well-characterized biological mycotoxin-adsorbing agent, Lactobacillus rhamnosus GG (LGG). At 37°C in phosphate-buffered saline (PBS, pH 7.0) containing 5 µg mL-1 of ZEN, the ZEN removal percentage of CK1 was 73.0%, which was significantly higher than that of HSCAS and LGG (45.9% and 48.4%, respectively). In the pH range of 2.5-8.0, CK1 removed up to 65% of ZEN. At temperatures between 4 and 42°C, CK1 removed more than 75% of ZEN. In the adsorption stability analysis, the amounts of ZEN removed by CK1 was over 30% even after five consecutive rounds of washing procedures. These findings demonstrated that CK1 displayed probiotic characteristics and removed ZEN effectively. Therefore, CK1 has a great potential for the development of feed additive to remove ZEN.


Assuntos
Bacillus licheniformis/metabolismo , Probióticos/farmacologia , Zearalenona/metabolismo , Adsorção , Ração Animal , Células CACO-2 , Escherichia coli O157/crescimento & desenvolvimento , Fusarium/metabolismo , Humanos , Concentração de Íons de Hidrogênio , Lactobacillus/metabolismo , Listeria monocytogenes/crescimento & desenvolvimento , Temperatura
8.
Dalton Trans ; 46(44): 15399-15406, 2017 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-29077111

RESUMO

New trimetallic cobalt, nickel and zinc complexes 1-3 coordinated by amine-bis(benzotriazole phenolate) ligands and ancillary acetate groups have been developed for the use of CO2/epoxide coupling. All complexes were structurally characterized by single crystal X-ray crystallography; tri-Co complex 1 is the first solid-state example in which three different geometrical configurations exist in the same benzotriazole phenoxide metal complex. Tri-nuclear complexes 1 and 2 with cobalt and zinc metal centers were demonstrated to be very active catalysts for cycloaddition of cyclohexene oxide with CO2 in the presence of ammonium salt co-catalysts to give cis-cyclohexene carbonate under the conditions of 80 °C and 300 psi initial CO2 pressure. Particularly, tri-cobalt complex 1 was found to efficiently couple CO2 with epoxides showing broad substrate scope, producing the corresponding cyclic organic carbonates with good activities and high selectivities. This is a successful example of catalysis for cyclic carbonate synthesis using one cobalt(ii) complex as a homogeneous catalyst.

9.
Med Eng Phys ; 35(7): 884-97, 2013 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-22995147

RESUMO

Atherosclerosis, a condition related to cholesterol build-up and thickening of the inner wall of the artery, narrows or occludes the artery lumen. The drug-eluting stent is a major breakthrough for the treatment of such coronary artery diseases. In recent years, another innovative variation of the drug-eluting stent with drug reservoirs has been introduced. It allows programmable drug delivery with spatial and temporal control and has several potential advantages over traditional drug-eluting stents. However, creating such reservoirs on the stent struts may weaken the stent scaffolding and compromise its mechanical integrity. In this paper, the effects of these micro-sized through-hole drug reservoirs on several key clinically relevant functional attributes of the depot stent were investigated. Finite element models were developed to predict the mechanical integrity of a balloon-expandable stent at various stages such as manufacturing and deployment, as well as the stent radial strength and fatigue life. Results show that (1) creating drug reservoirs on a stent could impact the stent fatigue resistance to some degree; (2) drug reservoirs on the stent crowns led to much greater loss in all key clinical attributes than reservoirs on other locations; (3) reservoir shape change resulted in little differences in all key clinical attributes; (4) for the same drug loading capacity, larger and fewer reservoirs yielded lower equivalent plastic strain and radial strength but higher fatigue safety factor; and (5) the proposed depot stent was proven to be a feasible design. Its total drug capacity could be tripled with acceptable marginal trade-off in key clinical attributes. These results can serve as the guidelines to help future stent designs to achieve the best combination of stent mechanical integrity and smart drug delivery in the future, thereby opening up a wide variety of new treatment potentials and opportunities.


Assuntos
Stents Farmacológicos , Análise de Elementos Finitos , Desenho de Prótese , Simulação por Computador , Humanos , Teste de Materiais , Estresse Mecânico
10.
Dalton Trans ; 40(28): 7423-33, 2011 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-21695289

RESUMO

A series of aluminium derivatives containing substituted bidentate and symmetrical tridentate pyrrolyl ligands, [C(4)H(3)NH(2-CH(2)NH(t)Bu)] and [C(4)H(2)NH(2,5-CH(2)NH(t)Bu)(2)], in toluene or diethyl ether were synthesized. Their reactivity and application for the ring opening polymerization of ε-caprolactone have been investigated. The reaction of AlMe(3) with one equiv. of [C(4)H(3)NH(2-CH(2)NH(t)Bu)] in toluene at room temperature affords [C(4)H(3)N(2-CH(2)NH(t)Bu)]AlMe(2) (1) in 70% yield by elimination of one equiv. of methane. Interestingly, while reacting AlMe(3) with one equiv. of [C(4)H(3)NH(2-CH(2)NH(t)Bu)] in toluene at 0 °C followed by refluxing at 100 °C, [{C(4)H(3)N(2-CH(2)N(t)Bu)}AlMe](2) (2) has been isolated via fractional recrystalliztion in 30% yield. Similarly, reacting AlMe(3) with two equiv. of C(4)H(3)NH(2-CH(2)NH(t)Bu) generates [C(4)H(3)N(2-CH(2)NH(t)Bu)](2)AlMe (3) in a moderate yield. Furthermore, complex 1 can be transformed to an aluminium alkoxide derivative, [C(4)H(3)N(2-CH(2)NH(t)Bu)][OC(6)H(2)(-2,6-(t)Bu(2)-4-Me)]AlMe (4) by reacting 1 with one equiv. of HOC(6)H(2)(-2,6-(t)Bu(2)-4-Me) in toluene via the elimination of one equiv. of methane. The reaction of AlR(3) with one equiv. of [C(4)H(2)NH(2,5-CH(2)NH(t)Bu)(2)] in toluene at room temperature affords [C(4)H(2)N(2,5-CH(2)NH(t)Bu)(2)]AlR(2) (5, R = Me; 6, R = Et) in moderate yield. Surprisingly, from the reaction of two equiv. of [C(4)H(2)NH(2,5-CH(2)NH(t)Bu)(2)] with LiAlH(4) in diethyl ether at 0 °C, a novel complex, [C(4)H(2)N(2-CH(2)N(t)Bu)(5-CH(2)NH(t)Bu)](2)AlLi (7) has been isolated after repeating re-crystallization. Furthermore, reacting one equiv. of C(4)H(2)NH(2,5-CH(2)NH(t)Bu)(2) with AlH(3)·NMe(3) in diethyl ether generates an aluminium dihydride complex, [C(4)H(2)N(2,5-CH(2)NH(t)Bu)(2)]AlH(2) (8), in high yield. Additionally, treating 8 with one equiv. of HOC(6)H(2)(-2,6-(t)Bu(2)-4-Me) in methylene chloride produces [C(4)H(2)N(2,5-CH(2)NH(t)Bu)(2)][OC(6)H(2)(-2,6-(t)Bu(2)-4-Me)]AlH (9) with the elimination of one equiv. of H(2). The aluminium alkoxide complex 4 shows moderate reactivity toward the ring opening polymerization of ε-caprolatone in toluene.

11.
Dalton Trans ; 39(37): 8748-58, 2010 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-20697649

RESUMO

A series of diarylamido phosphine ligands of the type N-(2-dihydrocarbylphosphinophenyl)-2,6-dialkylanilide 1a-d have been prepared and employed to investigate the coordination chemistry of zinc. Protonolysis of ZnMe2 with one equivalent of N-(2-diphenylphosphinophenyl)-2,6-dimethylaniline (H[1a]) produced a mixture of [1a]ZnMe (2a) and Zn[1a]2 (4a), whereas that involving ZnEt2 gave exclusively the three-coordinate [1a]ZnEt (3a). In contrast, treatment of ZnR2 (R = Me, Et) with N-(2-diphenylphosphinophenyl)-2,6-diisopropylaniline (H[1b]), N-(2-diisopropylphosphinophenyl)-2,6-dimethylaniline (H[1c]), or N-(2-diisopropylphosphinophenyl)-2,6-diisopropylaniline (H[1d]) under similar conditions generated quantitatively the corresponding three-coordinate zinc methyl 2b-d and zinc ethyl 3b-d. The bis-ligand complexes 4a,b,d were isolated by either protonolysis of alkyls 2-3 with one equivalent of H[1] or metathesis of ZnX2 (X = Cl, OAc) with the corresponding lithium derivatives 5. Attempts to prepare [1a-d]ZnX (X = Cl, OAc) were not successful regardless of stoichiometry of the starting materials employed. Alcoholysis of zinc alkyls 2-3 led undesirably to protonation on the amido nitrogen donor of 1, highlighting perhaps its higher basicity than alkyls. The reaction of ZnCl2 with H[1c] generated the phosphorus-bound adduct {H[1c]ZnCl(mu-Cl)}2 (6c). Interestingly, attempts to deprotonate 6c with n-BuLi produced unexpectedly the alkylated product [1c]Zn(n-Bu) (7c) instead of [1c]ZnCl; analogous reactions employing NEt3 led to Lewis base substitution to give H[1c] and [ZnCl2(NEt3)]2. Structural characterization of all new compounds was achieved by multi-nuclear NMR spectroscopy (1H, 13C, 31P, and 7Li) and X-ray crystallography (2c-d, 3c, 4d, 5c-d, and 6c) where appropriate. On the basis of the NMR and X-ray data, in combination with the synthetic investigations, the steric nature of these amido phosphine ligands is recognized to follow the order of 1a < 1b < 1c < 1d. Interestingly, zinc alkyls 2-3 are all active initiators for catalytic ring-opening polymerization of ε-caprolactone whereas the bis-ligand complexes 4 are not.

12.
Inorg Chem ; 48(16): 8004-11, 2009 Aug 17.
Artigo em Inglês | MEDLINE | ID: mdl-19606842

RESUMO

A series of monomeric, dimeric, and trimeric calcium compounds containing substituted pyrrolyl or ketiminate ligands were synthesized, and characterized by NMR spectroscopy and single crystal X-ray diffractometry. The reaction of Ca[N(SiMe(3))(2)](2)(THF)(2) with 1 equiv of [C(4)H(3)NH(2-CH(2)NEt(2))] in toluene generates the dimeric complex, [Ca{N(SiMe(3))}[mu-eta(1):eta(5)-{C(4)H(3)N(2-CH(2)NEt(2))}]](2) (1) in which two substituted pyrrolyl ligands bind two Ca centers in a eta(1) and eta(5) fashion. The reaction between Ca[N(SiMe(3))(2)](2)(THF)(2) and 2 equiv of [C(4)H(3)NH(2-CH(2)NEt(2))] in THF yields a monomeric calcium compound Ca[C(4)H(3)N(2-CH(2)NEt(2))](2)(THF)(2) (2) that exhibits a facial octahedral geometry on the central Ca atom. Similarly, the reactions of Ca[N(SiMe(3))(2)](2)(THF)(2) with 1 and 2 equiv of OCMeCHCMeNHAr (Ar = 2,6-diisopropylphenyl) generate [Ca(OCMeCHCMeNAr){N(SiMe(3))(2)}](2) (3) and [Ca(mu-OCMeCHCMeNAr)(OCMeCHCMeNAr)](2) (4), respectively. In 3, the Ca atom possesses a distorted tetrahedral geometry where as in 4, a square plane is developed by the two calcium atoms with the bridging participation of two oxygen atoms from two ketiminate ligands. The in situ reaction of OCMeCHCMeNHAr, Ca[N(SiMe(3))(2)](2)(THF)(2), and isopropyl alcohol results in a trimeric calcium alkoxide compound Ca(3)(mu-OCMeCHCMeNAr)(2)(OCMeCHCMeNAr)(mu(3)-O-(i)Pr)(2)(mu(2)-O-(i)Pr) (5). Compounds 1, 2, and 5 showed good catalytic activity in the ring-opening polymerization of epsilon-caprolactone and l-lactide.

13.
Chemistry ; 14(31): 9747-53, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-18792038

RESUMO

A series of dialuminum compounds have been synthesized and their reactivity and application for lactide polymerization have been studied. The reaction of AlH3 x NMe3 with [C4H3NH(2-CH2NHtBu)] in diethyl ether generated a dimeric aluminum hydride compound, [[[C4H3N(2-CH2NtBu)]AlH]2] (1). The structure of 1 was confirmed by spectroscopy of a deuterated analogue of 1 with an Al--D function. Direct treatment of [C4H3NH(2-CH2NHtBu)] with LiAlH4 in diethyl ether resulted in colorless crystals of [[Li[micro-eta1:eta5-C4H3N(2-CH2NtBu)]2Al]2] (2) in 80 % yield after recrystallization from a toluene solution. The micro-eta1:eta5-pyrrolyl protons exhibit high-field shifts at delta=5.73, 6.15, and 6.72 comparable to a similar eta5-bonding mode in the literature. Treatment of 1 with 1 equiv acetone oxime or acetone in dichloromethane gave [[[C4H3N(2-CH2NtBu)]Al[varkappaO,varkappaN-(ON==CMe2)]]2] (3) and [[[C4H3N(2-CH2NtBu)]Al(O--CHMe2)]2] (4) in 67 % and 60 % yield, respectively. Compounds 1-4 have been characterized by X-ray diffractometry and were used as catalysts for epsilon-caprolactone polymerization.

14.
Chem Commun (Camb) ; (43): 5444-6, 2005 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-16261241

RESUMO

(C5Me5R)2Ta2Cl4 (d2-d2) disproportionates under dinitrogen to [(C5Me4R)TaCl2]2(mu-N2) and the D3h cluster cation (C5Me4R)3Ta3(mu-Cl)6+ with anionic (C5Me4R)TaCl4-.

15.
J Am Chem Soc ; 125(9): 2641-51, 2003 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-12603152

RESUMO

Agostic interactions in yttrium alkyls are structure dependent. Primary alkyl yttrium complexes have beta-CH(2) agostic interactions at low temperature, but a shift toward alpha-agostic interactions occurs on warming. For the more crowded beta-disubstituted yttrium alkyls, an alpha-CH(2) agostic interaction is seen. The thermodynamics of alkene binding to the primary alkyl yttrium complex Cp(2)YCH(2)CH(2)CH(CH(3))(2) (2) depend strongly on the structure of the alkene. A single allylic substituent on the alkene has a small effect on alkene binding, but a second allylic substituent has a large destabilizing effect. Propene binding to yttrium alkyls is largely independent of the nature of the alkyl ligand. Equilibrium constants for propene binding to n-, gamma-substituted, beta-substituted, and secondary alkyl yttrium complexes are similar. The rate of migration of an alkyl group to a coordinated alkene depends strongly on the structure of the alkyl group: n-alkyl approximately gamma-substituted >> beta-substituted >> alpha-substituted. The approximately 200-fold slower insertion of propene into Cp(2)YCH(2)CH(CH(3))(2) (6) than that into Cp(2)YCH(2)CH(2)CH(CH(3))(2) (2) is therefore due to kinetically slow migration of the beta-disubstituted alkyl group of 6 and not to differences in the equilibrium binding of propene. Processes related to chain transfer and site epimerization at the metal center are also reported.

16.
J Am Chem Soc ; 125(7): 1688-9, 2003 Feb 19.
Artigo em Inglês | MEDLINE | ID: mdl-12580580

RESUMO

Reduction of the organoditantalum allene complex (eta-C5Me4R)2Ta2(mu-X)X3(mu-eta1,eta3-C3H4) (R = Me (Cp*), Et; X = Cl, Br) with sodium amalgam leads to the propynylidene complex (eta-C5Me4R)2Ta2(mu-H)2X2(mu-HCCCH) by a formal double 1,3-C-H activation of the allene ligand. The solid-state molecular structure contains a planar HCCCH ligand bridging, in parallel coordination mode, the two tantalum atoms, with the HCCCH and Ta atoms coplanar. Key structural features are a Ta-Ta distance of 2.8817(7) A, propynylidene C-C-C angle of 153.7(13) degrees , C-C distance of 1.370(8) A, Ta-C(central) distance of 2.194(9) A, and Ta-C(terminal) distance of 1.970(9) A. Molecular orbital calculations on the complex at the RHF/SBK(d) and B3LYP/LanL2dz levels of theory demonstrate that the propynylidene ligand is best viewed formally as an allenediylidene(4-) ligand bonded to two d0 tantalum atoms via two Ta=C(terminal) double bonds and an unusual three-center, two-electron bridge bond involving both tantalum atoms and a lone pair on the planar, tetracoordinate central carbon. There is no net Ta-Ta bonding based on the orbital analysis.

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