The coordination chemistry of saturated molecules

Our understanding of bonding in transition metal complexes, as well as our ability to use that understanding in the synthesis and application of new species, has evolved over the last 100 years; and in some sense this special feature on the coordination chemistry of saturated molecules may be considered to represent its culmination. The nature of complexes between transition metal ions and neutral molecules such as ammonia was first correctly described by Werner around the beginning of the 20th century. Interpretations in terms of electronic bonding theories followed soon after. The key feature, of course, is the availability of a low-energy filled "lone pair" orbital available for donation to a vacant orbital on the electron-accepting metal ion

An Analysis of Sportsman Activity Data Collection Methods for North Dakota

Resource /Energy Economics and Policy,

SOCIAL, ECONOMIC, AND INSTITUTIONAL INCENTIVES TO DRAIN OR PRESERVE PRAIRIE WETLANDS

Land Economics/Use,

AGRICULTURAL LAND DRAINAGE COSTS AND RETURNS IN MINNESOTA

The objectives of this study are to (1) introduce some of the topics relative to on-farm drainage decisions in rural Minnesota, (2) briefly describe on-farm drainage methods, (3) estimate the current costs of constructing on-farm drains, (4) estimate the returns to agricultural land drainage, and (5) examine the economic feasibility of on-farm drainage in Minnesota.Land Economics/Use,

Impact of Inundation and Changes in Garrison Diversion Project Plans on the North Dakota Economy

This report attempts to identify the economic consequences of the Garrison Diversion Unit and North Dakota's Missouri River impoundments from the state's perspective. The authors hope it will assist individuals and groups making decisions affecting the future development of North Dakota's water resources.Resource /Energy Economics and Policy,

Intra- and Intermolecular C−H Activation by Bis(phenolate)pyridineiridium(III) Complexes

A bis(phenolate)pyridine pincer ligand (henceforth abbreviated as ONO) has been employed to support a variety of iridium complexes in oxidation states I, III, and IV. Complexes (ONO)IrL_2Me (L = PPh_3, PEt_3) react with I_2 to cleave the Ir–C bond and liberate MeI, apparently via a mechanism beginning with electron transfer to generate an intermediate Ir(IV) complex, which can be isolated and characterized for the case L = PEt_3. The PPh_3 complex is transformed in benzene at 65 °C to the corresponding phenyl complex, with loss of methane, and subsequently to a species resulting from metalation of a PPh_3 ligand. Labeling and kinetics studies indicate that PPh_3 is the initial site of C–H activation, even though the first observed product is that resulting from intermolecular benzene activation. C–H activation of acetonitrile has also been observed

Activation of a C−H Bond in Indene by [(COD)Rh(μ_2-OH)]_2

The air- and water-tolerant hydroxy-bridged rhodium dimer [(COD)Rh(μ_2-OH)]_2 cleanly activates the aliphatic C−H bond in indene to generate [(COD)Rh(η^3-indenyl)]. The mechanism involves direct coordination of indene to the dimer followed by rate-determining C−H bond cleavage, in contrast to the previously reported analogous reactions of [(diimine)M(μ_2-OH)]_2^(2+) (M = Pd, Pt), for which the dimer must be cleaved before rate-determining displacement of solvent by indene. Another difference is observed in the reactions with indene in the presence of acid: the Rh system generates a stable η^6-indene 18-electron cation, [(COD)Rh(η^6-indene)]+, that is not available for Pd and Pt, which instead form the η^3-indenyl C−H activation products. The crystal structure of [(COD)Rh(η^6-indene)] is reported

A Versatile Ligand Platform that Supports Lewis Acid Promoted Migratory Insertion

A helping hand: Incorporation of Group 2 Lewis acids into a macrocycle appended to a phosphine ligand attached to a rhenium carbonyl complex promotes otherwise unfavorable transformations of coordinated CO (see scheme; M=Ca, Sr). These Lewis acids form relatively weak M-O bonds, thereby enabling release of organic products from the metal center

Oxidative aromatization of olefins with dioxygen catalyzed by palladium trifluoroacetate

Molecular oxygen can replace sacrificial olefins as the hydrogen acceptor in the palladium trifluoroacetate catalyzed dehydrogenation of cyclohexene and related cyclic olefins into aromatics. One of the major drawbacks of the homogeneous system is the tendency of the palladium trifluoroacetate to precipitate as palladium(0) at elevated temperatures. The use of better ligands affords catalysts that can operate at higher temperatures, although they are less reactive than palladium trifluoroacetate

JT9D jet engine performance deterioration

The analytical techniques utilized to examine the effects of flight loads and engine operating conditions on performance deterioration are presented. The role of gyroscopic, gravitational, and aerodynamic loads are shown along with the effect of variations in engine build clearances. These analytical results are compared to engine test data along with the correlation between analytically predicted and measured clearances and rub patterns. Conclusions are drawn and important issues are discussed