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Targeting of the PD1/PD-L1 immune checkpoint pathway has rapidly gained acceptance as a therapeutic strategy for a growing number of malignancies. Testing for expression of PD-L1 in tumor cells and immune cells has been used as a companion or complementary test for drugs targeting the PD1/PD-L1 pathway. We evaluated the results of PD-L1 testing in a large reference lab cohort. Using Food and Drug Administration-approved methods and interpretive instructions for each individual test, 62,896 cases were evaluated for PD-L1 using antibody clone 22C3, 28-8, SP142, or SP263. Case data analyzed included test results and information on tumor location and clinical history. No clinical outcome information was available and no attempt was made to correlate PD-L1 results with any other tests performed. The following numbers of cases were evaluated: 22C3 with tumor proportion score [n = 52585], 22C3 with combined positive score [n = 2631], 28-8 [n = 4191], SP142 [n = 850], and SP263 [n = 70]. In 22C3/tumor proportion score cases, the general results were as follows: negative 33.1% (n = 17,405), (low) expression 33.9% (n = 17,822), and high expression 29.5% (n = 15,486). In cases identified as metastatic, the results were as follows: negative 35.9% (n = 1411), (low) expression 30.8% (n = 1211), and high expression 30.7% (n = 1208). We found broad ranges of expression in tumor types with increasing positivity, as adenocarcinomas were reported as poorly differentiated, whereas squamous cell carcinomas showed more positivity as tumors were described as well-differentiated. The results of many individual tumor types were evaluated and showed, in general, high levels of positive expression. Practical challenges and observations of PD-L1 stain results and interpretation are also discussed.

In the reaction of the ionic complex of manganese based on 5,6-dicarba-nido-decaborane [1,1,1-(CO)3-isonido-1,2,4-MnC2B8H10]- tmdaH± (1) (tmdaH+- protonated form of N,N,N′,N′-tetramethyl-1,8-diaminonaphthalene) with triphenylphosphine (PPh3) in the presence of boron trifluoride etherate (BF3⋅Et2O) in benzene, the neutral complex 1,1,1-(CO)3–7-PPh3-isonido-1,2,4-MnC2B8H9 (2) was isolated as one of the main products. The position of the PPh3 substituent in the carborane ligand was established by 1H, 11B, 31P, 13C, [11B−11B]-COSY, 1H{11B} NMR spectroscopy methods and confirmed by X-ray diffraction analysis.

Reaction of the deprotonated medium-size non-icosahedral carborane 5,6-nido-C2B8H12 (1) with Re(CO)5Cl affords tricarbonyl anionic complexes of Re [1,1,1-(CO)3-isonido-1,2,4-ReC2B8H10]- as PPh4- 3a and tmndH- 3b salts (tmnd — N,N,N′,N′-tetramethyl-1,8-diaminonaphtaline). Treatment of [tmndH][1,1,1-(CO)3-isonido-1,2,4-MC2B8H10]- (M = Mn 2b, Re 3b) with the equivalent amount of CuCl and PPh3 in CH2Cl2 leads to formation of two isomers of bimetallic complexes [1,3,7(6)-{Cu(PPh3)}-3,7(6)-μ-H2-1,1,1-(CO)3-isonido-1,2,4-MC2B8H8] (M = Mn 4, Re 5) with two B-H⋯Cu bonds. All newly obtained compounds were characterized by a combination of analytical and multinuclear NMR spectroscopic data and IR spectroscopy. The structures of complexes 3b and 4 were researched by X-ray diffraction studies. The nature of interaction between {Cu(PPh3)} and mangana-carborane fragments was clarified based on the computed electron density critical points (within QTAIM framework) and Density Overlap Regions Indicator (DORI) distributions. Transition state between the two diastereomers of 4 was located, the isomerization rate was found to be of order of 1 s−1.

The use of improved protocol for the reaction of rhodium acetylacetonate complexes (diene)RhAcac [diene is 1,5-cyclooctadiene or norbornadiene] with exo-nido-ruthenacarboranes 5,6,10-[RuCl(PPh3)2]-5,6,10-(μ-H)3-10-H-7,8-R2-7,8-C2B8H6 (R = H or Me) allowed us to synthesize three new binuclear complexes, wherein the ruthenium atom preserved exo-position and the rhodium-containing moiety coordinated to the open pentagonal face of exo-nido-complex. In addition, one known bimetallacarborane was also prepared for the evaluation of synthetic efficiency of the new procedure.

Treatment of an anhydrous CoCl 2 with the [Na][C 2 B 8 H 11 ] ( 1 ) generated in situ from the neutral ten-vertex dicarbon carborane [5,6- nido -C 2 B 8 H 12 ] ( 2 ) with NaH in THF at ambient temperature affords the new cobaltacarborane commo cluster closo,nido -[CoH(2,4-C 2 B 8 H 10 )(7,8-C 2 B 8 H 11 )] 1− isolated as its air-stable [Ph 4 P] + ( 3 ) and [Ph 3 PMe] + ( 4 ) salts. As was found from the crystallographically determined structure of 4 and based on the 1 H NMR spectroscopic data for both 3 and 4 , these anionic salts are composed of the Co–H unit that is sandwiched between two {C 2 B 8 } cages; one of these cages, the formally doubly charged [C 2 B 8 H 10 ] 2− ligand, is involved in the η 6 -coordination to the metal center, but another singly charged [7,8-C 2 B 8 H 11 ] 1− ligand, which retains one bridged B–H–B hydrogen atom, is involved through its CB 3 -open face in the η 4 -coordination to the cobalt atom. At room temperature, complexes 3 and 4 exhibited fluxional behavior in solution where the exchange between terminal Co–H and bridging B–H–B hydrogen atoms occurs. This is discussed in detail based on the comparable room- and low-temperature 1 H NMR spectra of 3 .

Quantum chemical calculations were carried out for exo-nido - and closo -ruthenacarborane clusters containing phosphine and diphosphine ligands. The calculated energies and geometric parameters of the complexes show that closo -ruthenacarboranes with seven- or eight-membered ω-diphosphaalkyl-substituted ruthenacycles are the most stable compounds in the studied series. The results explain the effect of the nature of the diphosphine ligand on the reactivity and catalytic activity of the ruthenacarboranes in ATRP processes.

The heating of the isomeric [1-(η6-1,4-Me2C6H4)-3-Cl-isonido-1,2,4-RuC2B8H9] (1) or [1-(η6-1,4-Me2C6H4)-6-Cl-isonido-1,2,4-RuC2B8H9] (2) complexes (i) in a 1,4-Me2C6H4 solution at 85 °C as well as (ii) in a melt at 165 °C afforded mixtures of isomeric isonido- and closo-ruthenacarboranes, which differ in the positions of the chlorine substituent and the carbon atoms in the cage ligand. Structures of all new isomeric complexes have been established on the basis of analytical and multinuclear NMR data and were characterized by single-crystal X-ray diffraction studies. Also presented are the results of the quantum chemical calculations for the ground and the transition states of the reaction (i), which proved to be basis for the suggestion of interconversion scheme for these isomers.

The heating of a mixture of 14-e [Ph2P(CH2)nPPh2]FeCl2 (n = 3 or 2) with the [K]+ salt of the [nido-7,8-C2B9H12]− mono-anion under gentle reflux in benzene affords either the paramagnetic (17-electron) complex [3,3-(dppp)-3-Cl-closo-3,1,2-FeC2B9H11] isolated in 15% yield or a mixture of the paramagnetic complex [3,3-(dppe)-3-Cl-closo-3,1,2-FeC2B9H11] (46% yield) and the diamagnetic complex [commo-8,8′-μ-(Ph2PCH2CH2PPh2)-3,3′-Fe{1,2-C2B9H10}2] (10% yield). All three novel ferracarboranes were characterized by spectroscopic (EPR or NMR) data and single-crystal X-ray diffraction.

Reactions of [ exo -5,6,10-{Cl(Ph 3 P) 2 Ru}-5,6,10-(μ-H) 3 -10-H- nido -7,8-C 2 B 9 H 8 ] ( 1 ) with 1,5-bis(diphenylphosphino)pentane ( 2 ) in benzene either at ambient temperature for ca 2 days or under gently reflux for 30 min in anaerobic conditions both proceed with the replacement of PPh 3 ligands on the ruthenium center with the diphosphine to form diamagnetic (18-electron) closo complex [3,3-{κ 2 -{Ph 2 P(CH 2 ) 5 PPh 2 }}-3-Cl-3-H- closo -3,1,2-RuC 2 B 9 H 11 ] ( 3 ). On heating in benzene, 3 in the presence of a small amount of CCl 4 affords stable paramagnetic (17-electron) species [3,3-{κ 2 -{Ph 2 P(CH 2 ) 5 PPh 2 }}-3-Cl- closo -3,1,2-RuC 2 B 9 H 11 ] ( 5 ) along with traces of ortho -phenylenecycloboronated closo complex, ( 7 ). The latter complex was prepared in higher yields by thermal treatment of either 3 or 5 under more severe conditions in toluene at 110 °C. Thermolysis of 7 in boiling toluene in the presence of a small amount of CCl 4 afforded the new paramagnetic complex ( 8 ), featuring bis( ortho -cycloboronation) of both P-phenyl groups located at the same phosphorus atom of the ruthenium bound dppt ligand; a minor amount of chloro-cage-substituted complex ( 9 ) was also isolated from the latter reaction as the by-product. All new closo -ruthenacarboranes obtained were characterized by a combination of analytical, multinuclear NMR (for even-electron species) or EPR (for odd-electron species) data and, in addition, by single-crystal X-ray diffraction studies of three paramagnetic complexes 5 , 7 and 8 .

The reaction of the ruthenacarborane exo - nido -5,6,10-[Cl(Ph 3 P) 2 Ru]-5,6,10-(m-H) 3 -10-H-7,8-(Ph) 2 -7,8-C 2 B 9 H 6 with phenylacetylene in dichloromethane in the presence of triethylamine at ambient temperature affords exo - nido -5,6,10-[(Ph 3 P) 2 Ru]-5,6-(μ-H) 2 -10-[μ-(PhC=CH)]-10-H-7,8-(Ph) 2 -7,8-C 2 B 9 H 6 containing vinylene bridge group between carborane framework and ruthenium atom. Structure of the complex has been determined by X-ray diffraction study.

Reactions of [3,3-(PPh3)2-3-Cl-3-H-3,1,2-closo-RuC2B9H11] (1) and its exo-nido isomer [exo-5,6,10-{Ru(Ph3P)2Cl}-5,6,10-(μ-H)3-10-H-7,8-nido-C2B9H8] (2) with NH4PF6 in methanol or ethanol solution followed by heating in the presence of an excess of phenylacetylene (3) affords a mixture of two isomeric closo species [3,3-{(1′-3′-η3):(5′,6′-η2)-ortho-C6H4PPh2CHC(Ph)CHCHPh}-8-(σ–CH CHPh)-3,1,2-closo-RuC2B9H10] (4) and [3,3-{(1′-3′-η3):(5′,6′-η2)-ortho-C6H4PPh2CHC(Ph)CHCHPh}-4-(σ–CH CHPh)-3,1,2-closo-RuC2B9H10] (5) in which boron vertexes in β- and α-sites with respect to the cage carbons bear the (E)–CH CHPh group. The X-ray diffraction study of 4 together with the multinuclear NMR data for 4 and 5 revealed that such an unusual η3:η2-phosphacarbocyclic ligand in both isomeric complexes is formed by specific insertion of the initially metal-bound PPh3 group into the chain of two alkyne molecules coupled in a “head-to-tail” fashion around the metal vertex.

The room-temperature metallation reactions of the K+ salt of the [7,8-(PhCH2)2-7,8-nido-C2B9H10]− anion (1) with the COD-metal μ-chloride dimers [(η4-C8H12)2Rh2(μ-Cl)2] (2) and [(η4-C8H12)2Ir2(μ-Cl)2] (3) in benzene/ethanol solution gave formally 16-electron pseudocloso-type complexes with the η3-cyclooctenyl ligand at the metal vertices, [3-{(1–3-η3)-C8H13}-1,2-(PhCH2)2-pseudocloso-3,1,2-MC2B9H9] [4, M = Rh(III); 5, M = Ir(III)]. No evidence supporting the existence of an agostic C–H⋯M bonding interaction in these compounds was obtained either from the crystallographic or the phase-sensitive 2-D [1H–1H] NOESY/EXSY studies of 4. The extraordinary stability of complexes 4 and 5 can therefore be associated with their cage-deformed cluster structures, where electronically-deficient (16-electron) metal centers are believed to be stabilized by additional electron density released from the polyhedral C–C bond cleavage. DFT solid-state calculations performed for closo (18-electron) and pseudocloso (16-electron) Rh(III) complexes, [3-(η5-C5Me5)-1,2-(PhCH2)2-closo-3,1,2-RhC2B9H9] (6, C–C, 1.7397 A) and [3-{(1–3-η3)-C8H13}-1,2-(4′-MeC6H4)2-pseudocloso-3,1,2-RhC2B9H9] (9, C⋯C, 2.420(2) A), showed that the electron density transfer from the carborane moiety to the rhodium center is marginally greater for complex 9, in accordance with the idea that electronics rather than sterics play a crucial role in the stabilization of 16-electron pseudocloso-metallacarborane species.

The room temperature reactions between [Rh2(η5-C5Me5)2Cl4] (1) and [K][7-R1-8-R2-7,8-nido-C2B9H10] (2a–d: a, R1 = R2 = H; b, R1 = R2 = Me; c, R1 = H, R2 = PhCH2; d, R1 = R2 = PhCH2) in solution of C6H6–EtOH mixture (4:1) to give [3-(η5-C5Me5)-1-R1-2-R2-3,1,2-closo-RhC2B9H9] (3a–d), respectively, have been shown to proceed through the formation of the first step ionic intermediates of the type [(η5-C5Me5)Rh(μ-Cl)3Rh(η5-C5Me5)][7-R1-8-R2-7,8-nido-C2B9H10] (4a–d). All ionic compounds 4a–d were isolated in the solid state and characterized by a combination of analytical, IR and multinuclear NMR data, including a single-crystal X-ray diffraction study of 4d. The structure of 3d (R1 = R2 = PhCH2), the first 12-vertex closo-type metallacarborane species bearing sterically demanding C,C′-dibenzylsubstituted carborane ligand, has also been determined by an X-ray crystallography.

An essential step in the development of any modelling tool is the validation of its predictions. This paper describes a study conducted within the Chernobyl exclusion zone to acquire data to conduct an independent test of the predictions of the ERICA Tool which is designed for use in assessments of radiological risk to the environment. Small mammals were repeatedly trapped at three woodland sites between early July and mid-August 2005. Thermoluminescent dosimeters mounted on collars were fitted to Apodemus flavicollis, Clethrionomys glareolus and Microtus spp. to provide measurements of external dose rate. A total of 85 TLDs were recovered. All animals from which TLDs were recovered were live-monitored to determine (90)Sr and (137)Cs whole-body activity concentrations. A limited number of animals were also analysed to determine (239,240)Pu activity concentrations. Measurements of whole-body activity concentrations and dose rates recorded by the TLDs were compared to predictions of the ERICA-Tool. The predicted (90)Sr and (137)Cs mean activity concentrations were within an order of magnitude of the observed data means. Whilst there was some variation between sites in the agreement between measurements and predictions this was consistent with what would be expected from the differences in soil types at the sites. Given the uncertainties of conducting a study such as this, the agreement observed between the TLD results and the predicted external dose rates gives confidence to the predictions of the ERICA Tool.

Different types of 11–13-vertex metallacarboranes of platinum metals with unsaturated π-hydrocarbon ligands derived from mono- and polycyclic diolefins are reviewed. The purpose is to provide an overview of significant findings and trends in the synthetic and structural chemistry of these compounds. Some basic information on their catalytic and unique chemical properties, including the results on fluxional behavior and transformations of agostic (C–H⋯M) metallacarboranes in solution, are also discussed.

Reactions of [ exo-nido -5,6,10-{Cl(Ph 3 P) 2 Ru}-5,6,10-(μ-H) 3 -10-H-7,8-R 2 -7,8-C 2 B 9 H 6 ] ( 1 , R = H; 2 , R = Me) with the chiral (2S,4S)-2,4-bis(diphenylphosphino)pentane ( 3 , S , S -bdpp) ligand proceed in benzene with replacement of both PPh 3 ligands on the metal center with the diphosphine affording the chelate exo-nido complexes [ exo-nido -5,6,10-{Cl( S , S -bdpp)Ru}-5,6,10-(μ-H) 3 -10-H-7,8-R 2 -7,8-C 2 B 9 H 6 ] ( 7 , R = H) and ( 8 , R = Me), respectively. A relatively fast and irreversible rearrangement of 7 into its closo isomer [ closo -3,3-( S , S -bdpp)-3-Cl-3-H-3,1,2-RuC 2 B 9 H 11 ] ( 4 ) occurs in solution already at room temperature. On the contrary, exo-nido -to- closo conversion of 8 proceeds in benzene (or much faster in toluene) only on heating and yields 17-electron paramagnetic complex [ closo -3,3-( S , S -bdpp)-3-Cl-1,2-Me 2 -3,1,2-RuC 2 B 9 H 9 ] ( 9 ). All exo-nido - and closo -ruthenacarboranes obtained were characterized by a combination of analytical, multinuclear NMR or EPR spectroscopic data and, in addition, by X-ray diffraction studies of both dimethylated complexes 8 and 9 .

The presence of low-frequency large-amplitude modes in the vibrational spectrum, experimental and computed data on interboron distances and the results of the topological analysis of the electron density distribution in 2,3-C 2 B 9 H 11 , the molecule of a neutral 11-vertex dicarbaborane, lead to the conclusion that this polyhedron is not a deltahedron. This species lacks at least four two-center B–B bonds and thus it is formed not by triangular faces only. Hence, this dicarbaborane, as well as monocarbaborate [2-CB 10 H 11 ] − , another representative of 11-vertex polyhedra, do not have the closo -structure, traditionally ascribed to both by formal [2 n +2]-electron count.

Treatment of [exo-nido-{Cl(Ph3P)2Ru}-μ-(H)3-10-H-7,8-C2B9H8] (1) with the (2S,4S)-(−)-2,4-bis(diphenylphosphino)pentane (3, BDPP) while heating in toluene results in the formation of three novel optically active diphosphine–ruthenium closo complexes, 18e diamagnetic (−)-[closo-3-Cl-3,3-{(S,S)-BDPP}-3-H-3,1,2-RuC2B9H11] (4), and 17e paramagnetic (−)-[closo-3-Cl-3,3-{(S,S)-BDPP}-3,1,2-RuC2B9H11] (5) along with its ortho-cycloboronated derivative (−)-[closo-3-Cl-3,3-{(S,S)-Ph2PCH(CH3)CH2CH(CH3)PPh- (6). Both odd-electron complexes 5 and 6 were characterized by single-crystal X-ray diffraction analysis.

The mixed-ligand di-m-chloro-bridged rhodium dimers [(?2-C8H14)(?4-2-methylbuta-1,3-diene)Rh(µ-Cl)]2 and [(?2-C8H14)(?4-2,3- dimethylbuta-1,3-diene)Rh(µ-Cl)]2 were synthesized and characterized. These compounds are key precursors in the preparative syn- thesis of the acyclic (p-allyl)-closo-rhodacarborane complexes [3-{p-(R”-allyl)}-1-R-2-R’-closo-3,1,2-RhC2B9H9], which were obtained earlierviathe one-pot metallation of the K+ salts of the [7-R-8-R’-nido-7,8-C2B9H10]– anions with [(?2-C8H14)4Rh2(µ-Cl)2] in the presence of substituted buta-1,3-diene ligands.

The presence of two low-frequency large-amplitude modes in the vibrational spectrum, experimental and computed data on B–B interatomic distances and the results of a topological analysis of the electron density distribution in the molecule of an 11-vertex monocarbaborate [2-CB10H11]− lead to the conclusion that this polyhedron is not rigid, missing at least four double-center B–B bonds and thus being formed not only by triangular faces. Hence, this carbaborane does not have the closo-structure traditionally ascribed to it on formal [2n+2]-electron count grounds.

Reactions of [OsCl2(PPh3)3] 1 with the [NEt4]+ salts of the [6-Ph-nido-6-CB9H11]− anion 2 and the [arachno-6-CB9H14]− anion 3 each proceed selectively in methanol solution with the elimination of one boron-containing fragment from the starting cluster polyhedron, yielding together a short series of three novel 10-vertex hydridoosmamonocarbaboranes of isocloso {OsCB8} cluster geometry.

A facile ligand-exchange method based on the direct reaction of either three-bridge exo-nido complex [exo-5,6,10-{Cl(Ph3P)2Ru}- 5,6,10-(μ-H)3-10-H-nido-7,8-C2B9H8] or its closo isomer [3,3-(PPh3)2-3-Cl-3-H-3,1,2-closo-RuC2B9H11] with chelating N,N-donor ligands was employed to synthesize the N,N-diamine-closo-ruthenacarborane complexes [3,3-{κ2-4,4’-R2-2,2’-(C5H3N)2}-3-PPh3-closo-3,1,2-RuC2B9H11] (R = H, But) and [3,3-{κ2-phen}-3-PPh3-closo-3,1,2-RuC2B9H11].

The [7-Me3N-nido-7-CB10H12] (1), after being treated with two molar equiv. of Proton Sponge, reacts with [(η4-C10H12)2Rh2(μ-Cl)2] (2) in benzene–ethanol solution affording two isomeric monocarbon (η-dicyclopentenyl)-closo-rhodacarborane complexes, differing in hapticity of the carbocyclic ligand, viz. [2,2-{(2′,3′-η2):(5′-η1)-C10H13}-1-(Me3N)-2,1-closo-RhCB10H10] (3) and [2-{(1′-3′-η3)-C10H13}-1-(Me3N)-2,1-closo-RhCB10H10] (4). Isomeric compounds 3 and 4 were characterized by analytical, multinuclear NMR spectroscopic data as well as by single-crystal X-ray diffraction study, which revealed the existence of an agostic C–H⋯Rh interaction in both the species.

The first η2-olefinic monocarbon metallacarbone closo-2-(Ph3P)-1-N,2-[μ-(η2-CH2CHCh2)]-1-N-(σ-CH2CHCH2)-2,1- RhCB10H10 has been prepared by the reaction of the dimeric anion {[Ph3PRhB10H10CNH2]2-μ-H}−[PPN]+ with allyl bromide and characterized by a combination of spectroscopic methods and a single-crystal X-ray diffraction study. The variable temperature 1H and 13C NMR studies revealed the fluxional behavior of the η2-olefinic complex in CD2Cl2 solution which is associated with the allyl side-chain exchange process.

A variety of metallacarboranes, synthesized and structurally characterized by the authors are reviewed. These complexes are derived from platinum metals (Rh, Ru, Os) and isomeric nido -carborane anions [ nido -C 2 B 9 H 12 ] − and involve non-hydrocarbon (i.e. hydride, chloride, phosphine) as well as π -diene/dienyl ligands at the metal vertex.

The catalytic reduction of the exocyclic methylene group of methacycline (A) leads to the formation of two diastereoisomers, doxycycline (B, the α-epimer) and 6-epi-doxycycline (C, the β-epimer), with a selectivity which markedly depends on the nature of hydrocarbon and carborane ligands of closo-(π-cyclodienyl)rhodacarborane catalysts. Neutral norbornadienyl complexes with unsubstituted carborane ligands [closo-3,3-(η2,3-C7H7CH2)-3,1,2-RhC2B9H11] (1) and [closo-2,2-(η2,3-C7H7CH2)-2,1,7-RhC2B9H11] (7) are more active and afford higher selectivity in the formation of doxycycline than those having mono- or di-substituents at the carborane cage, [closo-3,3-(cyclodienyl)-1-R-2-R′-3,1,2-RhC2B9H9] (R = H, R′ = Me, PhCH2; R = R′ = Me; cyclodienyl = η2,3-C7H7CH2 or η-C10H13) as well as those from the closely related series of η5-cyclopentadienyl complexes [(η2,3-C7H7CH2)Rh(η5-C5Rn)]+PF6− (Rn = H5, Me5, or H2-1,2,4-Ph3). Mechanistic aspects of the hydrogenation reaction of methacycline are sketched. The results of the X-ray diffraction study of the best catalyst 1 are reported.

A novel 12-vertex monocarbon hydridorhodacarborane closo -2,2-(Ph 3 P) 2 -2- H -1-(Me 3 N)-2,1-RhCB 10 H 10 1 has been synthesized by the reaction of Rh(PPh 3 ) 3 Cl ( 2 ) with nido -B 10 H 12 CNMe 3 ( 3 ) under alkaline conditions. At low temperature 1 exists as a mixture of two preferred conformers in solution, both having C S symmetry, in accord with the hindered rotation of the (Ph 3 P) 2 RhH vertex with respect to the CB 4 face of the monocarbon carborane cage. Complex 1 readily reacts with chlorine-containing reagents to form mononuclear 16-electron closo -2-(Ph 3 P)-2-Cl-1-(Me 3 N)-2,1-RhCB 10 H 10 ( 5 ), whose structure was unambiguously confirmed by an X-ray diffraction study. The results of an X-ray diffraction study of the closely related dicarbon carborane derivative closo -3,3-(Ph 3 P) 2 -3-Cl-3,1,2-RhC 2 B 9 H 11 ( 10 ), prepared from closo -3,3-(Ph 3 P) 2 -3- H -3,1,2-RhC 2 B 9 H 11 by analogy with 5 , are also reported.

We study experimentally and numerically the effect of the phase of a periodic resonant perturbation-signal on a scaling law for signal amplification and classical squeezing in a CO2 laser with modulated losses in the vicinity of a period-doubling bifurcation. We obtain a π-periodical phase dependence in the scaling power which for maximal signal amplification has the value − 2 3 . Experimental results are in a good agreement with numerical calculations. The numerical simulations also show that in the phase range corresponding to classical squeezing the scaling power can take either negative or positive values, depending on the signal phase.

The existence of optimal timing for fast switching on stable and unstable orbits is explained on the base of map dynamics. The complexity of attractive basins is shown for relaxation regimes of generation.

OsCl2(PPh3)3 is a Cyclopropanation catalyst using ethyl diazoacetate with a variety of activated alkenes; OsCl2(PPh3)3 is however less active than RuCl2(PPh3)3 for the decomposition of the diazo reagent and the subsequent Cyclopropanation.

The response of a CO 2 laser with losses modulated at frequency Ω to a loss perturbation of frequency Ω/2 as well as the response at the idler frequency is investigated experimentally and numerically near the onset of a period-doubling bifurcation under conditions in which the relaxation oscillation frequency of the CO 2 laser is larger than Ω. Strong amplification of the perturbation signal below the bifurcation point and deamplification above it have been observed. We have found that the laser response depends on the amplitude and phase of the perturbation signal and that the maximum amplification is proportional to a certain power of the perturbation amplitude which, for the parameters used, is −0.6. We show that the idler-to-signal ratio decreases with increasing perturbation amplitude. Reasonable agreement between numerical and experimental results has been obtained.

The laser response to δ-functional cavity losses perturbations near a period-doubling instability is investigated theoretically and experimentally. The effects of small pulsed signal amplification and classical squeezing have been demonstrated in a driven CO2 laser. These effects can be used for an enhancement of the sensitivity of intracavity measurements.

Doxycycline (2), a tetracycline antibiotic extensively used in chemotherapy, was obtained stereoselectively from the hydrogenation of methacycline (1), catalysed by novel rhodium-carborane complexes.

Novel ruthenacarborane clusters exhibit high activity as cyclopropanation catalysts in reactions between ethyl diazoacetate and alkenes.

An intracavity Raman laser as a dynamical system with stochastic behaviour is investigated. Pulsating instabilities, mode-locking and possible features of a chaotic behaviour of the Q -switched ruby laser induced by intracavity stimulated Raman scattering are observed.

Novel exo-nido-ruthenacarboranes, 5,6,10-[CI(Ph3P)2Ru]-5,6,10-μ-(H)3-10-H-7,8-R2C2B9H6 (1; R = H, structurally characterized by an X-ray diffraction study, and 2; R = Me) have been prepared by reaction of RuCl2 (PPh3)3 and [nido-7,8-R2C2B9H10]− K+ in diethyl ether-tetrahydrofuran; in the solid state clusters 1 and 2 contain tridentate nido–carborane ligands bound to the RuII atom through three Ru—H—B bridging hydrogen bonds, whereas in solution they exist as an equilibrium mixture of isomeric exo-nido-bis(triphenylphosphine)chlorohydridoruthenacarboranes formed as a result of the cleavage of one of the Ru—H—B bonds with the formation of a new Ru—B σ-bond and a simultaneous hydrogen atom shift to the metal atom.