Stepwise and selective synthesis of chelating, multimetallic and mixed-metal π-diborene complexes.

The reaction of a pyridyl-substituted, doubly Lewis base-stabilised diborene with different amounts of copper(I) precursors led to the formation of the first chelating π-diborene complexes, the first π-diborene complexes in which metals are bound to both faces of the BB bond, and the first mixed-metal π-diborene species.

Perceived leadership quality and empathy among Indian undergraduate medical students.

BACKGROUND: Efficient leaders from the medical fraternity may understand healthcare in depth. Empathy is important for patient care, job satisfaction, and the psychological well-being of doctors. Empathic leadership is concerned with an interest in the people around them. This study aimed to observe the perceived leadership quality and empathy among Indian medical undergraduate students, find any correlation between them, and assess age, sex, and semester of study as predictor variables for leadership and empathy. MATERIALS AND METHODS: An online cross-sectional survey was conducted on Google Forms with undergraduate medical students in India with a convenient snowball sample. The Abbreviated Self Leadership Quality (ASQL) was used to find the leadership quality and the eight-item Empathy Quotient (EQ-8) to find the empathy. Spearman's correlation coefficient was calculated between ASQL and EQ-8 score. Age, sex, and semester were used as predictor variables in regression analysis with leadership and empathy as dependent variables. RESULT: A total of 439 (50.8% male, 49.2% female) Indian undergraduate students participated in the study. Males showed higher leadership qualities. There was no gender difference in empathy. Leadership was positively correlated (rs =0.13, P = .006) with empathy in the overall sample. The age (P = .001), sex (P < .0001), and semester of study (P < .0001) successfully predicts leadership (F = 57.167, P < .0001). Although age, sex, and semester combined successfully predict empathy (F = 5.31, P = .001), individually, only a semester of study (P = .009) significantly contributes to the prediction. CONCLUSION: Male and female medical students show a similar level of empathy but male shows higher leadership quality. Leadership and empathy are positively correlated; hence, students with higher leadership quality would show higher empathy and vice versa. The age, sex, and semester of study are determinants of leadership whereas semester of study is the determinant of empathy.

Giant Congenital Melanocytic Nevus with Congenital Neurofibroma: A Case Report.

BACKGROUND: Giant congenital melanocytic nevus (GCMN) is characterized by its large size and potential for transformation into melanoma. It can be associated with other neural cristopathies, including neurofibroma, however, it has not previously been described with a congenital neurofibroma. CASE REPORT: A newborn girl presented with a large congenital neurofibroma arising in a bathing trunk type of giant congenital melanocytic nevus. CONCLUSION: Congenital neurofibromas can be associated with (or a component of) a GCMN.

Electron-Precise Dicationic Tetraboranes: Syntheses, Structures and Rearrangement to an Alkylidene Borate-Borenium Zwitterion and a 1,3-Azaborinine.

Carbene-stabilized symmetrical and unsymmetrical dicationic tetraboranes, featuring an electron-precise tetraborane chain, were synthesized and fully characterized. Reactions of these tetraboranes with reductants/bases give rise to different outcomes according to the conditions employed, including: 1) reduction and rearrangement of the tetraborane chain to give a zwitterionic alkylidene borate-borenium species; 2) cleavage of the tetraborane chain to afford a 1,3-azaborinine; and 3) reduction of the supporting ligands to provide a diamino dipotassium salt. The zwitterionic alkylidene borate-borenium species can be viewed as an analogue of the base-stabilized diborenes. NMR spectroscopy and DFT calculations reveal a highly polarized B-B bond in the zwitterionic alkylidene borate-borenium, in which the formal oxidation states of the boron atoms can be considered as -1 and +2. These results suggest the considerable potential of tetraboranes as synthons for low-valent boron species.

Adrenal and Mesenteric Teratomas in Infants: Common Tumors in Uncommon Sites.

Teratomas are common tumors in children. The most common sites are gonads, however, several extragonadal sites are well known such as sacrococcygeal region, mediastinum, head and neck, stomach, and vagina. Occasionally, teratomas occur in unusual sites which pose diagnostic difficulties. Here, we describe two cases of infantile teratomas with unusual presentation. The first case was a 6-month-old girl who presented with a mass in the right side of the abdomen. Computed tomography (CT) scan showed a solid-cystic mass in the right suprarenal region. The second was a 4-month-old boy who came with a huge abdominal mass. Contrast-enhanced CT showed a tumor arising from the jejunal mesentery. On microscopic examination, they were diagnosed as mature and immature teratoma, respectively. Although neuroblastoma is the most common infantile adrenal neoplasm, the possibility of teratoma should be considered for cystic adrenal lesions. Mesenteric teratoma can be difficult to distinguish radiologically from the more common lymphangioma; however, accurate diagnosis is important in view of long-term follow-up for teratomas because of the possibility of malignant transformation.

Hydroboration reactions using transition metal borane and borate complexes: an overview.

In recent years, the chemistry of transition metal borane and borate complexes has advanced fast with reasonable growth. Frequent utilisation of these complexes in hydrofunctionalisation reactions is one of the key driving forces for their development. As a result, the important role of borate complexes in the hydroboration/hydrosilylation/hydroamination of unsaturated organic species has been successfully demonstrated together with the isolation of many different boron-containing transition metal complexes such as borataallyl, vinylborane, silyl complexes featuring the known bonding modes of boron. Both the uncatalysed and catalysed hydroboration reactions using the transition metal borane/borate complexes are known, which show these complexes' huge potential. Careful investigation and fine-tuning of the electronic and steric properties of the borane/borate ligands has facilitated the synthesis of these transition metal complexes which are convenient for use in the hydroboration reactions. Furthermore, the systematic development of this field has established the connection between the structure and reactivity of these complexes and their utilisation in hydroboration reactions. This Frontier sheds light on the recent developments that have been made with hydroboration reactions using transition metal borane/borate complexes. Also, in this Frontier we have provided meaningful synthetic methods to make new boron-containing transition metal complexes together with mechanistic insights for some of these reactions.

Tunical Gliomatosis: An Uncommon Histological Entity.

Background Gliomatosis peritonei (GP) is characterized by widespread implants of mature glial tissue in the peritoneum. It is most often associated with immature or mature ovarian teratomas. Case Report: A 6-month old infant developed isolated gliomatosis involving the tunica vaginalis following excision of an immature sacrococcygeal teratoma in the neonatal period. Conclusion: Tunica vaginalis gliomatosis can occur in the setting of a retroperitoneal extragonadal congenital immature teratoma.

Clinicopathological Study of Primary Pediatric Gastrointestinal Lymphomas.

BACKGROUND: Primary gastrointestinal lymphomas (PGIL) are uncommon in children and account for <5% of all pediatric malignancies. The objective of our study was to analyze the prognostic factors of pediatric PGILs with reference to its histological subtypes, stage, and outcomes using immunohistochemistry. MATERIALS AND METHODS: Twenty cases were studied over 11 years. Clinicopathological profiles, histological details, and immunohistochemical (IHC) profiles were analyzed. RESULTS: The mean age at the presentation was 6 years. Using IHC stains (CD CD10, CD19, CD20, CD3, terminal deoxynucleotidyl transferase, BCL 2 and 6, PAX 5, and MUM1), diffuse large B-cell lymphoma (DLBCL) was most prevalent (45%), followed by Burkitt lymphoma (35%) and lymphoblastic lymphoma (20%). DLBCLs (9) were classified using the Han's algorithm. Six were activated B-cell and 3 were germinal center B-cell subtypes. The cases of lymphoblastic lymphoma and those in Stage I disease had the best prognosis. CONCLUSION: Pediatric PGILs have variable presentation, outcomes, and diverse treatment modalities depending on the histological subtypes. A panel of IHC stains can be a useful adjunct for the categorization and prognosis of pediatric PGILs.

Stabilization of dichalcogenide ligands in the coordination sphere of a ruthenium system.

The synthesis, structure and electronic properties of tetraruthenium dichalcogenide complexes displaying the exclusive coordination mode of dichalcogenide ligands have been discussed. The reactions of Li[BH2E3] (E = S or Se) with [ClRu(µ-Cl)(p-cymene)]2 (p-cymene = η6-{p-C6H4(iPr)Me}) at room temperature yielded tetrametallic dichalcogenide complexes [{Ru2Cl2(p-cymene)2}2(µ4,η2-E2)], 1-2 (E = S (1) and Se (2)). The solid-state X-ray structure of 1 shows that two {(p-cymene)RuCl}2 moieties are bridged by a S-S bond. In addition to 2, the reaction of Li[BH2Se3] with [ClRu(µ-Cl)(p-cymene)]2 also yielded a mononuclear tris-homocubane analogue [Ru(p-cymene){Se7(BH)3}] (3) which is an analogue of 1,3,3-tris-homocubane and possesses D3 symmetry. In order to isolate the Cp* analogue of 1, the reaction of [Cp*Ru(µ-Cl)Cl]2 with Li[BH2S3] was carried out, which led to the formation of bis/tris-homocubane derivatives [(Cp*Ru)2{µ-Sn(BH)2}] (n = 7 (4) and 6 (5)) along with the formation of ruthenium disulfide complexes [(RuCp*)2(µ,η2:η2-S2)(µ,η1:η1-S2)] and [(RuCp*)2(µ-SBHS-κ1B:κ2S:κ2S)(µ,η1:η1-S2)]. Complexes 1-5 have been characterized by multi-nuclear NMR, IR, UV-vis spectroscopy, and mass spectrometry and their molecular formulations (except 2) have been determined by single crystal X-ray crystallography. Furthermore, DFT calculations were performed that rationalize the stabilization of the dichalcogenide units (E22-) by the tetrametallic systems in 1-2.

Recent Advances in the Synthesis and Reactivity of Transition Metal σ-Borane/Borate Complexes.

The coordination of an element-element σ bond to a transition metal (TM) is both a fundamentally intriguing binding mode and of critical importance to metal-mediated bond activation mechanisms and catalysis, particularly the hotly contested field of C-H activation. TM σ complexes of dihydrogen (i.e., H-H) and silanes (H-SiR3) have been extensively studied, the latter being of interest as models for the (generally unstable and unisolable) σ complexes of alkanes (i.e., H-CR3). TM σ complexes of hydroboranes and hydroborates (i.e., H-BR2, H-BR3, (H-)2BR2) are somewhat less well studied but similarly have relevance to catalytic borylation reactions that are of high current interest to organic synthesis. Our two research groups have made significant contributions to elaborating the family of σ-borane/-borate complexes using two distinct approaches: while the Ghosh group generally starts from hydrogen-rich tetracoordinate boron species such as borates, the Braunschweig group starts from hypovalent and/or hypocoordinate boron building blocks. Through these two approaches, a wide range of species containing one or two σ-bound B-H ligands have been prepared, some with additional chelating donor sites. Over the past 2 years, the body of work on σ-borane/-borate complexes from our two research groups has significantly expanded, with a combined nine published articles in 2019-2020 alone. Very recent work from the Braunschweig group has led to the synthesis of the first bis(σ)-borane complexes of group 6 metals, as well as the synthesis of a series of novel bis(σ)-borane and bis(σ)-borate complexes of ruthenium and iridium, the former being useful precursors for pentacoordinate borylene complexes of Ru. Recent work from the Ghosh group has uncovered a remarkable diversity of structures with σ(B-H)-bound ligands from the combination of borohydrides and nitrogen/chalcogen-containing groups and heterocycles. These reactions, while in some cases producing conventional scorpionate-type chelating products, more frequently undergo fascinating rearrangements with unpredictable outcomes. This Account aims to highlight this recent acceleration of research progress in this area, particularly the distinct but related approaches of-and complexes produced by-our two research groups, in addition to relevant works from other groups where appropriate.

Adsorption Mechanism of Methylene Blue by Graphene Oxide-Shielded Mg-Al-Layered Double Hydroxide From Synthetic Wastewater.

Pollution of water resources by various pollutants is a global environmental issue, particularly, dye pollution has a major contribution to it. From various studies, it is confirmed that adsorption is an excellent remediation technique compared to others. Mg-Al-layered double hydroxides (LDHs) intercalated with NO3- ions act as an effective adsorbent-removing ionic species like heavy metal and dyes. Another popular nanomaterial is graphene oxide (GO), which is successfully used as an adsorbent for different pollutants like dye and heavy metal ions. It is prepared based on the modified Hummers method. In this study, GO was introduced on the surface of LDH to improve its adsorption capacity. The adsorption process is well described by the Freundlich model. The maximum adsorption capacity was obtained at around 0.5 and 0.85 mmol of methylene blue (MB) per gram of Mg-Al LDH and modified Mg-Al LDH with GO, respectively. The reaction kinetics of MB with both adsorbents is determined to be the pseudo-second-order. To get more insights of the mechanism, molecular dynamics (MD) simulation was conducted among the modified Mg-Al LDH with GO and MB molecules at both low- and high-concentration environments, which demonstrated that the developed composite adsorbs MB molecules predominantly onto its GO surface and then the MB molecules are adsorbed by the LDH surface. C-H···O (2.49-3.04 Å) and pi-donor···H-O (2.45-3.05 Å) are the major driving forces behind the strong adsorbability. Besides, S···H-O, S···O,N···O-H, pi···lone pair, pi···sigma, pi···cation, and alkyl···hydrophobic interactions play important roles in stabilizing the MB molecules onto the surface of the composite.

Utility of cell block preparation in diagnosis of paediatric abdominal neoplasms.

BACKGROUND: Paediatric abdominal neoplasms are fairly common. Fine needle aspiration cytology (FNAC) is used for the initial evaluation of paediatric abdominal neoplasms. However, sometimes FNA interpretation can be difficult on limited material, owing to tumour heterogeneity and overlapping features. Therefore, we attempted to obtain additional information using cell block (CB) preparation from residual aspiration material along with immunohistochemistry (IHC) to enhance the diagnostic accuracy. AIM: To evaluate the correlation between CB preparation and FNAC in diagnosis of paediatric abdominal tumours with the help of an extended panel of IHC markers and to highlight some of the diagnostic difficulties. MATERIALS AND METHODS: A total of 113 cases of paediatric abdominal masses were studied. In addition to routine FNA smears, CBs were prepared from the residual material for IHC analysis as considered appropriate. RESULTS: This study included a total of 113 children with abdominal masses. Histopathology following surgical resection was available in 53 cases. Histology was taken as gold standard to measure the diagnostic accuracy with reference to sensitivity (Sn), specificity (Sp), positive predictive value and negative predictive value. The Sn of FNA alone was 87.5% and Sp was 97.78%. The Sn and Sp increased with use of CB alone and were 100% and 97.78% respectively. The highest Sn and Sp were observed when CB was combined with IHC where both the values were 100%. CONCLUSION: CB with IHC is a useful adjunct to the routine FNA smears that further contributes to enhance the accuracy of the cytopathological diagnosis and is useful for choosing pre-operative chemotherapeutic regimen.

Development of a Low-cost Smartphone-connected Digital Microscope.

INTRODUCTION: Modern light microscopes are available with built-in illuminator and facility of photomicrography. This enables the microscopy to be ready for telemedicine. However, resource-limited settings still find difficulty in procuring those microscopes. AIM: The aim of this study was to upgrade a light microscope to a smartphone-connected digital microscope with minimal cost to make it ready for telemedicine. MATERIALS AND METHODS: A commercially available (price: ₹389) Universal Serial Bus (USB) web camera was set on the eyepiece and fixed with the help of an aluminum sheet. Light emitting diodes (LEDs), covered with an optical diffuser, were set below the condenser. The camera was connected to an Android smartphone with an application for capturing image and video. Sixteen faculty members provided their opinion about the new device. RESULTS: The smartphone-connected microscope was successfully used to focus and capture image and video of various slides. The images and videos were stored in the smartphone and shared via E-mail and other channels (e.g., WhatsApp and Telegram). This camera was also successfully connected to a laptop for projecting the real-time microscopic field on a screen. According to faculty members, focusing an object and capturing the image are the best features of the device; however, development of the device received lowest score. CONCLUSION: A light microscope was upgraded to telemedicine ready microscope with nominal cost and moderate effort. It can also be used in medical teachings as it can project real-time images of a slide under the microscope. As it is equipped with LEDs, powered by the same smartphone, it can be operated without daylight or during a power outage.

Role of Metals and Thiolate Ligands in the Structures and Electronic Properties of Group 5 Bimetallic-Thiolate Complexes.

Syntheses, structures, and electronic properties of group 5 metal-thiolate complexes that exhibit unusual coordination modes of thiolate ligands have been established. Room-temperature reaction of [Cp*VCl2]3 (Cp* = η5-C5Me5) with Na5[B(SCH2S)4] led to the formation of [Cp*VO{(SCH2)2S}] (1). The solid-state X-ray structure of 1 shows the formation of six-membered l,3,5-trithia-2-vanadacyclohexane that adopted a chair conformation. In a similar fashion, reactions of heavier group 5 precursors [Cp*MCl4] (M = Nb or Ta) with Na5[B(SCH2S)4] yielded bimetallic thiolate complexes [(Cp*M)2(µ-S){µ-C(H)S3-κ2S:κ2S',S″}{µ-SC(H)S-κ2C:κ2S‴,S''''}] (3a: M = Nb and 3b: M = Ta). One of the key features of molecules 3a and 3b is the presence of square-pyramidal carbon, which is quite unusual. The reactions also yielded bimetallic methanedithiolate complexes [(Cp*Nb)2(µ-S)(µ-SCH2S-κ2S,S')(µ,η2:η2-BH3S)] (2) and [(Cp*Ta)2(µ-O)(µ-SCH2S-κ2S,S')(µ-H){µ-S2C(H)SCH2S-κ2S″:κ2S‴,S''''}] (4). Complex 2 contains a methanedithiolate ligand that stabilizes the unsaturated niobaborane species. On the other hand, one ((mercaptomethyl)thio)methanedithiolate ligand {C2H4S3} is present in 4, which is coordinated to metal centers and exhibits the {µ-κ2S″:κ2S‴,S''''} bonding mode. Along with the formation of 3b and 4, the reaction of [Cp*TaCl4] with Na5[B(SCH2S)4] yielded [(Cp*Ta)2(µ-S){µ-(SBS)S(CH2S)2(BH2S)-κ2B:κ2S:κ4S',S″,S‴,S''''}] (5) containing a trithiaborate unit (BS3). Complex 5 consists of pentacoordinate boron that resides in a square-pyramidal environment. All the complexes have been characterized by multinuclear NMR, UV-vis spectroscopy, mass spectrometry, and single-crystal X-ray diffraction studies.

A new method of recording attendance improves the academic performance of medical students.

INTRODUCTION: Students' engagement during the collection of attendance (SEdCA) is a method where students write the answer to a question related to the topic of preceding 1-h lecture. Then, attendance is recorded by the teacher from the answer sheets. This method was introduced primarily to overcome difficulty in recording attendance from a class of high attendance. Its potential formative assessment capability has not yet been ascertained. With this background, the aim of this study was to evaluate the effect of the application of SEdCA as a method of formative assessment on the academic performance of first-year medical students. METHODS: This interventional, uncontrolled, before and after study was conducted on 93 first-year medical students. Part completion test (PCT) scores in anatomy before the application of SEdCA was considered as the pre-intervention academic performance. Then, 1-h lectures were designed according to SEdCA for a period of 3 months. The next PCT scores were taken as post-intervention performance and compared with the pre-intervention performance using paired t-test with α = 0.05. RESULTS: Ninety-three (female=38, male=55) first-year medical students with a mean age of 17.65±0.88 years participated in the study. There was a significant increase in theory (23.74±5.67 versus 26.40±5.17, t=3.31, P<0.001), practical (21.43±6.60 versus 24.08±5.16, t=6.95, P<0.001), and total (45.17±11 versus 50.47±9.17, t=8, P<0.001) scores in the post-intervention PCT. CONCLUSION: SEdCA may be applied to enhance the academic competency of first-year medical students. However, its impact should be evaluated further in multiple subjects in students of different years of study in more institutes for a generalized result.

Prescription digitization, online preservation, and retrieval on a smartphone.

BACKGROUND: Medical records are important documents that should be stored for at least 3 years after the commencement of the treatment of an adult patient in India. In a health care facility, patients' data is saved in an online or offline retrieval system. However, in the case of the primary care physician, the data is not commonly kept in an easily retrievable system. AIM: To test the feasibility of using a set of free web-based services in digitization, preservation, and retrieval of prescription on a smartphone by primary care physicians. METHODS: This study was conducted with 12 primary care physicians. They were provided hands-on guides on creating an online form for uploading a prescription and using an application for retrieval of the prescription on a smartphone. Their feedback on the training material was collected by a telephonic survey, which had a 10-point Likert-type response option. Then, an in-depth interview was conducted to ascertain their perception on the tutorial and the process of digitization and retrieval system. RESULTS: All of the participants were able to create an online form on their smartphone. They uploaded their prescription and associated data and were able to retrieve it. The physicians opined positively on the "cost of the system," "portability" on a smartphone and ease of the "tutorial". They opined negatively on the "limited storage," chances of "loss of data," and "time constraints" for entry of the patients' data. CONCLUSION: Free web-based and smartphone applications can be used by a primary care physician for personal storage and retrieval of prescriptions. The simple tutorial presented in this article would help many primary care physicians in resource-limited settings.

Stabilization of Classical [B2 H5 ]- : Structure and Bonding of [(Cp*Ta)2 (B2 H5 )(µ-H)L2 ] (Cp*=η5 -C5 Me5 ; L=SCH2 S).

The room-temperature reaction of [Cp*TaCl4 ] with LiBH4 ⋅THF followed by addition of S2 CPPh3 results in pentahydridodiborate species [(Cp*Ta)2 (µ,η2 :η2 -B2 H5 )(µ-H)(κ2 ,µ-S2 CH2 )2 ] (1), a classical [B2 H5 ]- ion stabilized by the binuclear tantalum template. Theoretical studies and bonding analysis established that the unusual stability of [B2 H5 ]- in 1 is mainly due to the stabilization of sp2 -B center by electron donation from tantalum. Reactions to replace the hydrogens attached to the diborane moiety in 1 with a 2 e {M(CO)4 } fragment (M=Mo or W) resulted in simple adducts, [{(Cp*Ta)(CH2 S2 )}2 (B2 H5 )(H){M(CO)3 }] (6: M=Mo and 7: M=W), that retained the diborane(5) unit.

Clinicopathological study of intestinal smooth muscles, interstitial cells of Cajal, and enteric neurons in neonatal jejuno-ileal atresia with special reference to muscle morphometry.

PURPOSE: To assess the thickness of the intestinal smooth muscle layer and analyze the distribution and density of interstitial cells of Cajal (ICC) and enteric neurons in the proximal and distal segments of neonatal jejuno-ileal atresia. METHODS: This is an observational study done over a period of one year in which fifteen cases of jejuno-ileal atresia were included. All the cases underwent laparotomy and resection of the atretic segment with variable portions of the dilated proximal segment and distal segment. Histopathological analysis was done on the sections taken from proximal segments (at 3 cm, 5 cm & 8 cm) and the distal segment (at 2 cm) from the atretic portion. The mean thickness of the inner circular muscle layer (ICML) and outer longitudinal muscle layer (OLML) was assessed in the above segments using image morphometry. In addition, we also analyzed the distribution and density of the ICCs and enteric neurons in the different segments using immunohistochemistry for c-kit and S-100, respectively. Controls included normal jejuno-ileal segments resected from postmortem cases (n=7) and other nonrelated surgeries (n=3). The findings were then compared with each-other and with normal controls. RESULTS: Mean thickness of ICML and OLML of the proximal segments at 8 cm was significantly lower than at 3 cm and 5 cm of ileal and jejunal atresias (p≪ 0.5). The mean thickness of ICML and OLML of distal segments at 2 cm was similar to the controls in all the atretic cases (p≫ 0.5). The mean ICML thickness at proximal 8 cm segment was similar to the distal segment of both ileal & jejunal atresias (p= 0.06 & 0.37 respectively). The mean thickness of the OLML of the proximal 8 cm segments was significantly more than that at the distal segment (p=0.008) in ileal atresias but was similar in cases of jejunal atresias (p=0.07). Both the proximal and distal segments of ileal as well as jejunal atresias showed reduction in distribution and density of ICCs, as compared to normal controls. The density of ICCs in proximal segments at 3 cm and 5 cm was similar in both ileal (p=0.33) and jejunal segments (p=0.41) but was significantly lower than the proximal 8 cm segments (p≪0.05).The distribution of ICCs in the proximal segment at 8 cm was similar to the distal segments (p≪0.05). S-100 staining showed dense expression of neurons and glial cells with presence of submucosal giant ganglia within the proximal dilated segments as compared to the distal segments and the controls, which were more marked at 3 cm and 5 cm levels than at 8 cm level. CONCLUSION: Muscle morphometry using image analysis is a simple technique to assess the thickness of the intestinal smooth muscle layers. There is significant smooth muscle hypertrophy along with marked alteration in density and distribution of ICCs and ENS in the dilated proximal segments up to 5 cm, and relatively milder changes at 8 cm levels, as compared to the distal segments and the controls. TYPE OF STUDY: Prognosis study. LEVEL OF EVIDENCE: Level II.

Hydroboration of Alkynes: η4-Alkene-Borane versus η4-E-Boratabutadiene.

A series of hydroborated η4-σ,π-alkene-borane complexes have been synthesized from the reaction of ruthenium-bis(σ)borate complex [Cp*Ru(µ-H)2BH(S-CH═S)] (1) and terminal as well as internal alkynes. Likewise, the reactions of manganese-bis(σ)borate complexes [Mn(CO)3(µ-H)2BHNCSC6H4(NL)] (L = NCSC6H4 or H) were explored with terminal alkynes that yielded boratabutadiene complexes [Mn(CO)3{(NCSC6H4)2N}{(R1MeC)═B(HC═CHR1)}] [R1 = phenyl (4a) or p-tolyl (4b)] via triple hydroboration of alkynes. These complexes feature a boratabutadiene ligand that is coordinated to a metal through the η4-CBCC mode. To the best of our knowledge, these are the first examples of η4-E-boratabutadiene-coordinated manganese complexes generated by the trans-hydroboration of alkynes. The steric and electronic effects of the borate ligands have been demonstrated using a less sterically hindered manganese-bis(σ)borate complex, [Mn(CO)3(µ-H)2BH(HN2CSC6H4)], that generated monohydroborated complexes [(CO)3Mn(µ-H)2(HN2CSC6H4)B(R1C═CHR2)] (for 6, R1 = Ph and R2 = H; for 7, R1 = p-Tol and R2 = H; for 8, R1 = R2 = Ph). Theoretical studies using density functional theory methods and chemical bonding analyses established the bonding and stability of these species.

Chalcogen stabilized trimetallic clusters: synthesis, structures, and bonding of [(Cp*M)3(E)6+m(BH)n] (M = Nb or Ta; E = S or Se; m = 0 or 1 or 2; n = 0 or 1).

In an effort to isolate the chalcogen-rich niobium analogue of [(Cp*Ta)3(µ-S)3(µ3-S)3BH], the room temperature reaction of [Cp*NbCl4] (Cp* = η5-C5Me5) with Li[BH2S3] was carried out. Although the objective of isolating the niobium analogue was not achieved, the reaction yielded a homocubane-type cluster [(Cp*Nb)3(µ-S)3(µ3-S)3(µ-S)BH], 1, and a hexa-sulfido cluster [(Cp*Nb)3(µ-S)6], 2. Cluster 1 is a notable example of a homocubane-type cluster in which one of the vertices of the homocubane is missing. Compound 1 may be considered as a hypo-electronic cluster with an electron count of 64 cve (cve = cluster valence electrons), whereas compound 2 shows the presence of two doubly bridging η1-S around each Nb-Nb bond. On the other hand, the room temperature reaction of [Cp*TaCl4] with selenaborate ligand, [LiBH2Se3], led to the formation of [(Cp*Ta)3(µ-Se)4{µ-Se2(Se2)}], 3. Compound 3 is one of the rarest examples having a Ta3Se6 core structure with a unique diselenide bridging fragment. The presence of a short Se-Se bond of this diselenide unit makes this molecule of further interest. All these compounds were characterized by 1H, 11B{1H} and 13C{1H} NMR spectroscopy, infrared spectroscopy, mass spectrometry, and single-crystal X-ray crystallography. Density functional theory (DFT) calculations were carried out to provide insight into the bonding and electronic structures of these chalcogen-rich trimetallic clusters.