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China has remained detached from the events in Afghanistan, generally playing a passive role during the US-led war in its neighbour and refusing to actively support any parties in the conflict. However, Beijing was prompt to embrace Taliban 2.0 as the new power in Kabul as Ashraf Ghani’s regime collapsed in the wake of the US withdrawal in August 2021. At first glance, this appears to be a shift in policy from China’s previous apathetic stance to actively taking the Taliban’s side. Yet, a closer look at China’s actions reveal that it has maintained a consistently narrow and pragmatic policy towards its neighbour since 2002. This article unpacks China’s remarkably consistent Afghanistan policy, identifying its basis in two primary interests: ensuring stability in its Xinjiang province and trade with Central Asia. As long as Beijing is able to secure the willing cooperation from the main parties within Afghanistan to securing these interests, it is indifferent as to who the authority in Kabul is.

Borylation of cyclic aryl–alkyl sulfones gives boronate esters by selective cleavage of C(sp2)–SO2 or C(sp3)–SO2 bonds via Cu-mediated or Cu-free processes.

The use of transition metals to catalyse the addition of hydridoboranes to unsaturated organic molecules was initially realised several decades ago. Although this area of chemistry received considerable attention at the time, interest in this reaction and its use in organic synthesis waned for several years. Like a phoenix rising from the ashes, this amazing catalytic reaction has grown to include the use of earth-abundant metal catalysts and a much wider range of organic substrates. Indeed, it is now commonly utilised as a diagnostic tool to assess the reactivity and catalytic ability of newly generated transition metal and main group complexes. As this field is progressing so rapidly, this review highlights some important advances up to the end of 2021 and into early 2022. Excluded from this review are 'hydroboration' reactions using diboron sources.

This study reports on the exploration of the phosphinoboration reaction with several thiosemicarbazones (R5R4NC(S)NR3N=CR1R2). Reactions between either Ph2PBpin (pin = 1,2-O2C2Me4) or Ph2PBcat (cat = 1,2-O2C6H4) with thiosemicarbazones containing a terminal primary or secondary amine afforded boron-containing heterocyclic 1,3,4-thiadiazoline products in excellent yield. The addition of Ph2PBpin to thiosemicarbazones containing an NMe2 group in the terminal position generated novel five-membered heterocycles in moderate yield, which included boron, sulfur, and nitrogen atoms. Heterocyclization of the thiosemicarbazones occurs preferentially in the presence of functional groups such as acetyl and pyridyl groups.

A novel protocol for the transition metal‐free 1,2‐addition of polyfluoroaryl boronate esters to aldehydes and ketones is reported, which provides secondary alcohols, tertiary alcohols, and ketones. Control experiments and DFT calculations indicate that both the ortho‐F substituents on the polyfluorophenyl boronates and the counterion K+ in the carbonate base are critical. The distinguishing features of this procedure include the employment of commercially available starting materials and the broad scope of the reaction with a wide variety of carbonyl compounds giving moderate to excellent yields. Intriguing structural features involving O−H⋅⋅⋅O and O−H⋅⋅⋅N hydrogen bonding, as well as arene‐perfluoroarene interactions, in this series of racemic polyfluoroaryl carbinols have also been addressed., Herein we report a transition metal‐free procedure for the base‐promoted 1,2‐addition of polyfluorophenylboronates to aldehydes and ketones to generate organofluorine‐containing alcohols in yields up to 93 %.

A nickel/N‐heterocyclic carbene (NHC) catalytic system has been developed for the borylation of aryl sulfoxides with B2(neop)2 (neop=neopentyl glycolato). A wide range of aryl sulfoxides with different electronic and steric properties were converted into the corresponding arylboronic esters in good yields. The regioselective borylation of unsymmetric diaryl sulfoxides was also feasible leading to borylation of the sterically less encumbered aryl substituent. Competition experiments demonstrated that an electron‐deficient aryl moiety reacts preferentially. The origin of the selectivity in the Ni‐catalyzed borylation of electronically biased unsymmetrical diaryl sulfoxide lies in the oxidative addition step of the catalytic cycle, as oxidative addition of methoxyphenyl 4‐(trifluoromethyl)phenyl sulfoxide to the Ni(0) complex occurs selectively to give the structurally characterized complex trans‐[Ni(ICy)2(4‐CF3‐C6H4){(SO)‐4‐MeO‐C6H4}] 4. For complex 5, the isomer trans‐[Ni(ICy)2(C6H5)(OSC6H5)] 5‐I was structurally characterized in which the phenyl sulfinyl ligand is bound via the oxygen atom to nickel. In solution, the complex trans‐[Ni(ICy)2(C6H5)(OSC6H5)] 5‐I is in equilibrium with the S‐bonded isomer trans‐[Ni(ICy)2(C6H5)(SOC6H5)] 5, as shown by NMR spectroscopy. DFT calculations reveal that these isomers are separated by a mere 0.3 kJ/mol (M06/def2‐TZVP‐level of theory) and connected via a transition state trans‐[Ni(ICy)2(C6H5)(η2‐{SO}‐C6H5)], which lies only 10.8 kcal/mol above 5., A nickel/N‐heterocyclic carbene (NHC) catalytic system has been developed for the borylation of aryl sulfoxides with B2(neop)2 (neop=neopentyl glycolato). A wide range of aryl sulfoxides with different electronic and steric properties were converted into the corresponding arylboronic esters in good yields. Elucidation of key mechanistic features of this newly developed reaction led to the identification of fully characterized nickel intermediates.

In 2020, the Sino-Indian Line of Actual Control (LAC) witnessed several violent clashes between the People’s Liberation Army (PLA) and the Indian military that resulted in a tense stand-off between the two highly mobilised armies and plunged Sino-Indian bilateral relations to its lowest point since the 1962 border war. Whilst confrontations between Chinese and Indian border forces are relatively commonplace, this recent crisis has proven remarkable due to the ferocity of the clashes and the alarming pace and degree to which established rules of engagement on the LAC have broken down. With both sides seemingly locked in a stalemate, it is prudent to reflect on the causes and significance of the current stand-off. This article argues that the crisis was largely precipitated by China’s calculation that India’s recent border infrastructure building activities and assertive domestic and foreign policy in the erstwhile state of Jammu and Kashmir could threaten the PLA’s tactical advantage along the border, and eventually undermine China’s hold over the disputed Aksai Chin region. Acting on these perceptions and sensing that a ‘window of opportunity’ could be rapidly closing, the Chinese government authorised the PLA to initiate actions to consolidate its advantageous position on the LAC. Although both militaries are fully mobilised and in close proximity across the LAC, both sides clearly recognise the decision to go to war would not benefit either side. Hence, both sides will need to engage in some deft diplomacy going forward to resolve the current crisis and to reset bilateral ties.

Organoboron compounds are well known building blocks for many organic reactions. However, under basic conditions, polyfluorinated aryl boronic acid derivatives suffer from instability issues that are accelerated in compounds containing an ortho‐fluorine group, which result in the formation of the corresponding protodeboronation products. Therefore, a considerable amount of research has focused on novel methodologies to synthesize these valuable compounds while avoiding the protodeboronation issue. This review summarizes the latest developments in the synthesis of fluorinated aryl boronic acid derivatives and their applications in cross‐coupling reactions and other transformations. image

The uncatalyzed addition of catecholborane to α-diimines has been examined. Reactions proceed smoothly at room temperature in the absence of a catalyst or additive, providing bis-hydroboration products with 3-coordinate boron centres or mono-hydroboration products with 4-coordinate boron centres, depending on the nature of the diimine reagent.

We report herein a mild procedure for the copper‐catalyzed oxidative cross‐coupling of electron‐deficient polyfluorophenylboronate esters with terminal alkynes. This method displays good functional group tolerance and broad substrate scope, generating cross‐coupled alkynyl(fluoro)arene products in moderate to excellent yields. Thus, it represents a simple alternative to the conventional Sonogashira reaction., BFF: A mild procedure is reported for the synthesis of alkynyl(fluoro)arenes via copper‐catalyzed oxidative cross‐coupling of polyfluorophenylboronate esters with terminal alkynes.

Defunctionalization of readily available feedstocks to provide alkenes for the synthesis of multifunctional molecules represents an extremely useful process in organic synthesis. Herein, we describe a transition metal-free, simple and efficient strategy to access alkyl 1,2-bis(boronate esters) via regio- and diastereoselective diboration of secondary and tertiary alkyl halides (Br, Cl, I), tosylates, and alcohols. Control experiments demonstrated that the key to this high reactivity and selectivity is the addition of a combination of potassium iodide and N,N-dimethylacetamide (DMA). The practicality and industrial potential of this transformation are demonstrated by its operational simplicity, wide functional group tolerance, and the late-stage modification of complex molecules. From a drug discovery perspective, this synthetic method offers control of the position of diversification and diastereoselectivity in complex ring scaffolds, which would be especially useful in a lead optimization program.

We report the first trans phosphinoboration of internal alkynes. With an organophosphine catalyst, alkynoate esters and the phosphinoboronate Ph2 P-Bpin are efficiently converted into the corresponding trans-α-phosphino-β-boryl acrylate products in moderate to good yield with high regio- and Z-selectivity. This reaction operates under mild conditions and demonstrates good atom economy, requiring only a modest excess of the phosphinoboronate. X-ray crystallography experiments allowed structural assignment of the unprecedented and densely functionalized (Z)-α-phosphino-β-boryl acrylate products.

This investigation examines the reactivity of phosphinoboronate esters Ph2PBpin (pin = 1,2-O2C2Me4) and Ph2PBcat (cat = 1,2-O2C6H4), as well as other phosphinoboron species, with various aryl and aliphatic acyl chlorides. These reactions proceed smoothly to give acyl phosphines of the type RC(O)PR'2 along with loss of a boron-chloride compound. In some cases, a second equivalent of the phosphinoboron species can add to the C[double bond, length as m-dash]O double bond at elevated temperatures to give the corresponding diphosphines RC(OBR''2)(PR'2)2. These ambiphilic diphosphines behave like substituted (1,1-bis(diphenylphosphino)methane) derivatives in a reaction of PhC(OBpin)(PPh2)2 (2a) with (η5-C9H7)Rh(η2-coe)2 (coe = cis-cyclooctene) affording the indenyl rhodium complex (η5-C9H7)Rh(PhC(OBpin)(PPh2)2) (3a) where the phosphines are bound to the metal centre in a κ2-P,P bidentate manner.

A Cu-catalysed borylation of aryl alkyl sulfones was developed for the high yield synthesis of versatile arylboronic esters using a readily prepared NHC-Cu catalyst. In addition, the selective cleavage of either alkyl(C)-sulfonyl or aryl(C)-sulfonyl bonds of a cyclic sulfone

Sreeram Chaulia, Trumped: Emerging Powers in a Post-American World. New Delhi: Bloomsbury India, 2019, 237 pp. ISBN: 978-9-3891-6594-4.

A practical and direct method was developed for the production of versatile alkyl boronate esters via transition metal-free borylation of primary and secondary alkyl sulfones. The key to the success of the strategy is the use of bis(neopentyl glycolato) diboron (B\(_{2}\)neop\(_{2}\)), with a stoichiometric amount of base as a promoter. The practicality and industrial potential of this protocol are highlighted by its wide functional group tolerance, the late-stage modification of complex compounds, no need for further transesterification, and operational simplicity. Radical clock, radical trap experiments, and EPR studies were conducted which show that the borylation process involves radical intermediates.

Organoboron reagents represent a unique class of compounds because of their utility in modern synthetic organic chemistry, often affording unprecedented reactivity. The transformation of the carbon-boron bond into a carbon-X (X = C, N, and O) bond in a stereocontrolled fashion has become invaluable in medicinal chemistry, agrochemistry, and natural products chemistry as well as materials science. Over the past decade, first-row d-block transition metals have become increasingly widely used as catalysts for the formation of a carbon-boron bond, a transformation traditionally catalyzed by expensive precious metals. This recent focus on alternative transition metals has enabled growth in fundamental methods in organoboron chemistry. This review surveys the current state-of-the-art in the use of first-row d-block element-based catalysts for the formation of carbon-boron bonds.

This study reports on the preparation of eight new boron-containing capsaicinoids bearing long aliphatic chains, as an expansion of our previous studies to include tertiary amide derivatives into our substrate scope. Our boron-moiety, a pinacolboronate ester (Bpin) fragment, has been incorporated in two locations: as an aryl substituent of the capsaicinoid produced by the reductive amination of veratraldehyde, or at the terminal end of an aliphatic substituent using an iridium catalyzed hydroboration reaction. We report that most compounds in our series show moderate antimicrobial and cytotoxic activity, surpassing activities noted in our previous study.

Boron oxide nanoparticles (nB2O3) are manufactured for structural, propellant, and clinical applications and also form spontaneously through the degradation of bulk boron compounds. Bulk boron is not toxic to vertebrates but the distinctive properties of its nanostructured equivalent may alter its biocompatibility. Few studies have addressed this possibility, thus our goal was to gain an initial understanding of the potential acute toxicity of nB2O3 to freshwater fish and we used a variety of model systems to achieve this. Bioactivity was investigated in rainbow trout (Oncorhynchus mykiss) hepatocytes and at the whole animal level in three other North and South American fish species using indicators of aerobic metabolism, behavior, oxidative stress, neurotoxicity, and ionoregulation. nB2O3 reduced O. mykiss hepatocyte oxygen consumption (ṀO2) by 35% at high doses but whole animal ṀO2 was not affected in any species. Spontaneous activity was assessed using ṀO2 frequency distribution plots from live fish. nB2O3 increased the frequency of high ṀO2 events in the Amazonian fish Paracheirodon axelrodi, suggesting exposure enhanced spontaneous aerobic activity. ṀO2 frequency distributions were not affected in the other species examined. Liver lactate accumulation and significant changes in cardiac acetylcholinesterase and gill Na+/K+-ATPase activity were noted in the north-temperate Fundulus diaphanus exposed to nB2O3, but not in the Amazonian Apistogramma agassizii or P. axelrodi. nB2O3 did not induce oxidative stress in any of the species studied. Overall, nB2O3 exhibited modest, species-specific bioactivity but only at doses exceeding predicted environmental relevance. Chronic, low dose exposure studies are required for confirmation, but our data suggest that, like bulk boron, nB2O3 is relatively non-toxic to aquatic vertebrates and thus represents a promising formulation for further development.

Phosphinoboration of diazobenzene with Ph2 PBR'2 cleanly affords products of the form Ph2 P(PhNNPh)BR'2 (2: R'2 =catechol, cat; 4: R'2 =phenanthrenediol, quin) and shows evidence of Ph2 P(PhNNPh)Bpin 7 (pin: pinacol). The mechanism of these reactions was probed computationally and shown to proceed via intermediates involving a diazobenzene-adduct of the boron center of the PB reagent. The resulting PNNB species 2 and 4 are shown to be frustrated Lewis pairs (FLPs). Despite the presence of weakly Lewis acidic boron centers, these species react with diazobenzene. Additionally, the FLP reactivity of 2 was further probed with 4-phenyl-1,2,4-triazole-3,5-dione, 1,10-phenanthroline-5,6-dione, and benzyl azide to give unique five-, six-, and eight-membered heterocyclic rings. Thus, phosphinoboration provides a new avenue to FLPs in which donor and acceptor sites are linked by nitrogen atoms.

The reactions of CO2 with a series of phosphinoboranes, including R2PBpin (R=Ph, tBu; pin=pinacol), R2PBMes2 (R=Ph, tBu; Mes=2,4,6‐Me3‐C6H2), and R2PBcat (R=Ph, tBu, Mes; cat=catechol) are described. Although R2PBpin and R2PBMes2 afford products of the form R2PCO2Bpin (R=Ph 1, tBu 4) and R2PCO2BMes2 (R=Ph 2, tBu 3), respectively, R2PBcat lead to further reaction affording the diphospha‐ureas, (R2P)2CO (R=Ph 5, tBu 6, Mes 7), together with O(Bcat)2. Computational studies provide insight into the mechanism, revealing an intermediate derived from double phosphinoboration of CO2., From CO2 to urea: The reactions of CO2 with a series of phosphinoboranes afford compounds of the form R2PCO2BR′2 and diphospha‐ureas, (R2P)2CO. Computational data reveals a mechanism, involving a double phosphinoboration of CO2.

The Sino-Indian border dispute has been effectively stalemated since the end of the 1962 Border War and remains a source of serious tension between the two Asian giants. Yet there were several instances throughout the 1950s and the early 1960s when the two sides could have resolved their dispute amicably. Curiously, despite several detailed historical accounts on how the Sino-Indian border dispute developed, there has been few systematic theoretical accounts exploring why this occurred. To address this gap, I utilise poliheuristic choice theory to examine the choices of the both the key decision-makers of the time, Mao Zedong and Jawaharlal Nehru. The poliheuristic choice theory illuminates why both Mao and Nehru initially chose status quo policies before embracing either compromise or escalation policies, when faced with domestic pressure at home and ideological impulses.

In this study we have studied the synthesis, characterization and catalytic activity of phosphinocopper(I) complexes [Cu(PPh3)3(NCCH3)][B(O2C6H4-4-R)2] (3a: R = H; 3b: R = Me; 3c: R = NO2) and [Cu(PPh3)3(NCCH3)][B(O2C6H3-3,5-di-tBu)2] (3d) containing weakly coordinating arylspiroborate ligands bearing various electronic and sterically defined characteristics. All new compounds have been characterized fully including single crystal X-ray diffraction studies for 3a and 3c and confirm that the arylspiroborate ligands do not coordinate to the copper atoms. Using these new metal complexes as precatalysts in the cyclisation of short chain alkynoic acids gave the corresponding exo-dig cyclic lactones exclusively.

We have investigated the addition of a simple phosphinoboronate ester, Ph2PBpin (pin = 1,2-O2C2Me4), to 2-diphenylphosphinobenzaldehyde (2-Ph2PC6H4C(O)H) and related aldimine derivatives (2-Ph2PC6H4C(NR)H) as a simple and effective strategy for generating unique diphosphine ligands bearing a pendant Lewis-acid Bpin group. These reactions proceed selectively to give one new product where the phosphide fragment has added to the aldehyde (or imine) carbon atom and the electron-deficient boron group has added to the electron-rich heteroatom. Preliminary studies show these new compounds can ligate to Pd(II) and Pt(II) metal centres. These novel metal complexes, as well as the organic soluble [MCl2(coe)]2 (M = Pd, Pt, coe = cis-cyclooctene) compounds, have been shown to be effective precatalysts in the cyclisation of alkynoic acids to give the corresponding exo-dig cyclic lactones. Reactions employing these metal complexes also generated unusual endo-dig cyclic lactones not traditionally observed in these cyclisation reactions. For instance, reactions of 4-pentynoic acid also afforded significant amounts of α-angelica lactone, a biologically-important compound traditionally prepared via the catalytic dehydration and cyclisation of levulinic acid.

A series of borylated conjugated trienes and skipped dienes is prepared by Ru-catalysed cross-dimerisation using alkynyl-, dienyl-, and vinyl boronates. These products are used as synthetic building blocks for polyene substructures by subsequent Pd-catalysed cross-coupling in a one-pot vessel without deprotection.

The reactions of the phosphinoboranes Ph2PBMes2, Ph2PBpin, and Ph2PBcat with the diazomethanes Ph2CN2, C12H8CN2, and EtO2CCHN2 are shown to give products of 1,1-phosphinoboration. The products (1–6) are shown to have PNB linkages with three-coordinate boron centers, whereas the products (EtOOC)CNN(PR2)(Bpin) (R = Ph 7, tBu 8) form zwitterionic heterocycles resulting from chelation of the ester carbonyl to boron. DFT calculations show that the reactions are initiated by N-to-B addition followed by 1,2-phosphinyl shift.

This preliminary study reports on the synthesis of two new boron-capsaicin derivatives containing either a short or long chain aliphatic tail group using an iridium catalyzed hydroboration reaction with pinacolborane. The boronate ester groups reside on the terminal position of the tail group and are necessary for the bioactivity of these compounds. Indeed, both compounds showed considerable activity against two Gram-positive bacteria, including Vancomycin-resistant Enterococcus. Vancomycin is considered the last resort medication for the treatment of septicemia, and new antibacterial agents that can treat sepsis are of paramount importance. The more lipophilic boron compound with the longer aliphatic chain also showed antifungal activity against Saccharomyces cerevisiae.

A highly efficient and general protocol for traceless, directed C3-selective C–H borylation of indoles with [Ni(IMes)2] as the catalyst is reported. Activation and borylation of N–H bonds by [Ni(IM...

In this study we have expanded upon a family of substituted pentacyclic oxadiazadiborinane derivatives from the condensation of carbohydrazide with ortho-formylphenyl boronic acid derivatives containing a variety of chemical and physical properties. All new complexes have been characterized fully including two single crystal X-ray diffraction studies which confirm the solid-state structure of these species along with an unusual methanol activation product, which appears to be a minor solid-state side product. The lack of inherent solubility of these compounds in common physiological media precluded us from doing traditional antimicrobial activities. To circumvent this problem, we incorporated these boron compounds into chitosan films. Only weak or moderate activities against Gram-negative and Gram-positive bacteria were observed in this study.

Grey seals (Halichoerus grypus) are a qualifying feature of three special areas of conservation (SACs) in Wales, yet relatively little is known of their site use along this coastline. Since 1992, many individuals and organisations have contributed to a grey seal photographic identification database held by Natural Resources Wales, which is one of the largest and oldest of its kind, providing key information from grey seal haul-out sites around the Celtic and Irish Seas. Here, we investigated spatial connectivity of haul-out sites and fidelity of adult females to breeding sites. The minimum number of adult female grey seals using the area between 1992 and 2016 was 2688. Individual capture histories and relative spatial transition probabilities (Pij) between pairs of location groups were calculated. Adjacent locations were highly connected (e.g. Lleyn Peninsula and Bardsey, Pij = 0.7) but connections spanned the entire region, up to 230 km apart (e.g. Skomer and Dee Estuary, Pij = 0.004). Resights were recorded within SACs (e.g. Lleyn Peninsula and Bardsey [Lleyn Peninsula and the Sarnau SAC], Pij = 0.7), between SACs (e.g. Bardsey and Skomer [Pembrokeshire Marine], Pij = 0.03), between SACs and non-designated areas (e.g. Skerries and Bardsey, Pij = 0.09) and between sites outside any protected area (e.g. Dee Estuary and Anglesey, Pij = 0.5). While inter-annual fidelity to breeding sites was high (Pij = 0.82–1), individual female grey seals moved throughout the region. This evidence of extensive site use beyond protected areas is important for the management and conservation of grey seals around Wales.

The addition of 4-ethyl-3-thiosemicarbazide to benzaldehyde and boronic acid containing derivatives afforded the corresponding thiosemicarbazones (1–3) or benzodiazaborines (4–6) depending on the position of the boronic acid within the ring. All compounds have been characterized fully including an X-ray diffraction study of the methoxy-containing benzodiazaborine 6. Attempts to coordinate thiosemicarbazones 2 and 3 to palladium(II) acetate were unsuccessful; however, addition of the non-boron-containing derivative 1 to palladium afforded complex 7 whose molecular structure was determined by an X-ray diffraction study. The initial bioactivities of compounds 1–7 were examined against two fungi, Aspergillus niger and Saccharomyces cerevisiae, and two bacteria, Bacillus cereus and Pseudomonas aeruginosa.

The stereoselective anti-addition of selenoboranes to α,β-acetylenic esters and amides was achieved in a transition metal-free context using catalytic amounts of PCy3. The reaction provides anti-3,4-selenoboration with concomitant delivery of α-vinyl selenides by protodeboronation with MeOH. Interestingly, in the absence of phosphine the selenoboration switches towards the formation of β-vinyl selenides. Theoretical calculations rationalize the regio- and stereoselectivity of the reaction by discovering a new mechanism for the anti-3,4-selenoboration. While the selenoborane is activated via the “push–pull” effect of B, the phosphine interacts with the β position of the alkynoate switching the polarity of the triple bond and favoring 1,3-selenoboration which provides the α-addition of the selenyl group. Then, the autocatalytic action of a second selenoborane reagent, which coordinates to the phosphorus ylide intermediate, determines the stereoselectivity and completes the catalytic process. Finally, the comparison of selenoborane reagents with diboranes and silaboranes, which have exhibited analogous reactivity, shows that the selenium moiety has a larger nucleophilic character favoring the performance of the reaction under mild conditions.

The addition of phosphinoboronate ester Ph2PBpin (pin = 1,2-O2C2Me4) (1) to a number of different N-heterocycles has been investigated. Reaction of 1 with pyridine resulted in highly selective formation of the corresponding 1,4-addition product, with addition of the electron-deficient Bpin group to the pyridine nitrogen atom and the phosphido group to the para carbon atom. Conversely, reactions of para-substituted pyridine derivatives oc-curred predominately to afford 1,2-addition products while quinoline reacted to afford the 1,2-adduct which ultimately isomerized to afford the corresponding 1,4-addition product. Preliminary computational studies have been undertaken to explore possible pathways for these transformations including transfer of the PPh2- anion from [B(PPh2)2pin]- to the 4-position of a borenium/boronium activated pyridine and concerted pathways for 1,2-addition via intramolecular nucleophilic attack of PPh2 at C2 of a Ph2PBpin-coordinated pyridine via a four-centered transition state and intramolecular transfer of PPh2 to the 2-position of a boron-activated pyridine in a phosphido-bridged dimer involving a six-centered transition state.

A series of iminophosphineplatinum(II) complexes have been prepared from pro-ligands derived from aniline derivatives containing electron-donating methoxy groups or electron-withdrawing fluorides and [PtCl2(η 2 − coe)]2 (coe = cis-cyclooctene). All new pro-ligands and metal complexes have been fully characterized, including an X-ray diffraction study for compound 11 (derived from para-methoxyaniline). Additionally, the molecular structure of a di-iminophosphineplatinum dication 11a has been determined. The platinum compounds showed no appreciable cytotoxic properties against two glioma cell lines using the MTT method.

Six Schiff base compounds have been prepared from the condensation of o-vanillin, 2,3-dihydroxybenzaldehyde and 2,3,4-trihydroxybenzaldehyde with 4-aminosalicylic acid and 5-aminosalicylic acid (5-ASA). Addition of these Schiff bases to [Pd(OAc)2] afforded the corresponding bis(salicylaldiminato)palladium(II) complexes in moderate to excellent yields. All new palladium complexes have been characterized fully using standard spectroscopic methods, elemental analyses and a single-crystal X-ray diffraction study in the case of 2e, the palladium complex containing Schiff base ligands derived from 5-ASA and 2,3-dihydroxybenzaldehyde. All derivatives of 5-ASA were examined for potential antimicrobial activities against two species of fungi, Aspergillus niger and Saccharomyces cerevisiae, as well as two species of bacteria, Bacillus cereus (Gram-positive) and Pseudomonas aeruginosa (Gram-negative).

Three new iminophosphines containing pinacol-derived boronate esters have been prepared and ligated to dichloridoplatinum(II) fragments. All compounds have been characterized fully, including an X-ray diffraction study carried out for the platinum complex 8, which is derived from 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)aniline. These three new platinum complexes, along with the non-boron containing control, have been examined for their initial cytotoxic properties against two glioma cell lines using the MTT method.