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941.
Dr. Sara Sabater Dr. David Schmidt Dr. Heidi Schmidt Dr. Maximilian W. Kuntze-Fechner Dr. Thomas Zell Connie J. Isaac Dr. Nasir A. Rajabi Harry Grieve Dr. William J. M. Blackaby Dr. John P. Lowe Prof. Stuart A. Macgregor Dr. Mary F. Mahon Prof. Dr. Udo Radius Prof. Michael K. Whittlesey 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(52):13221-13234
The addition of PPh2H, PPhMeH, PPhH2, P(para-Tol)H2, PMesH2 and PH3 to the two-coordinate Ni0 N-heterocyclic carbene species [Ni(NHC)2] (NHC=IiPr2, IMe4, IEt2Me2) affords a series of mononuclear, terminal phosphido nickel complexes. Structural characterisation of nine of these compounds shows that they have unusual trans [H−Ni−PR2] or novel trans [R2P−Ni−PR2] geometries. The bis-phosphido complexes are more accessible when smaller NHCs (IMe4>IEt2Me2>IiPr2) and phosphines are employed. P−P activation of the diphosphines R2P−PR2 (R2=Ph2, PhMe) provides an alternative route to some of the [Ni(NHC)2(PR2)2] complexes. DFT calculations capture these trends with P−H bond activation proceeding from unconventional phosphine adducts in which the H substituent bridges the Ni−P bond. P−P bond activation from [Ni(NHC)2(Ph2P−PPh2)] adducts proceeds with computed barriers below 10 kcal mol−1. The ability of the [Ni(NHC)2] moiety to afford isolable terminal phosphido products reflects the stability of the Ni−NHC bond that prevents ligand dissociation and onward reaction. 相似文献
942.
The total synthesis of the unusual 4-pyridone marine metabolite lodopyridone has been achieved by late stage manipulation of the related 4-pyrone. Key reactions include a Suzuki–Miyaura coupling to form the tetracyclic core and a modified Corey–Ganem–Gilman reaction to install the ethanolamide side-chain. 相似文献
943.
944.
William Y.C. Chen Ira M. Gessel Catherine H. Yan Arthur L.B. Yang 《Journal of Combinatorial Theory, Series A》2008,115(6):1069-1076
We introduce a statistic pmaj(P) for partitions of [n], and show that it is equidistributed with cr2, the number of 2-crossings, over all partitions of [n] with given sets of minimal block elements and maximal block elements. This generalizes the classical result of equidistribution for the permutation statistics inv and maj. 相似文献
945.
The notion of noncrossing linked partition arose from the study of certain transforms in free probability theory. It is known that the number of noncrossing linked partitions of [n+1] is equal to the n-th large Schröder number rn, which counts the number of Schröder paths. In this paper we give a bijective proof of this result. Then we introduce the structures of linked partitions and linked cycles. We present various combinatorial properties of noncrossing linked partitions, linked partitions, and linked cycles, and connect them to other combinatorial structures and results, including increasing trees, partial matchings, k-Stirling numbers of the second kind, and the symmetry between crossings and nestings over certain linear graphs. 相似文献
946.
947.
E. Maurer F. Hartmann F. Mylius F. Foerster G. Schoene H. Schenck Alexander Fischer G. T. Dougherty M. Dittrich A. Leonhard O. L. Barnebey J. V. Mc Crae R. L. Dowdell L. Jordan J. G. Thompson J. S. Acken J. H. S. Dickenson P. Herasymenko G. Pondélik Th. R. Cunningham R. J. Price C. H. Herty G. R. Fitterer J. E. Eckel J. J. Egan W. Crafts und A. B. Kinzel 《Fresenius' Journal of Analytical Chemistry》1935,101(1-2):50-53
Ohne Zusammenfassung 相似文献
948.
William E. Kunze 《Fresenius' Journal of Analytical Chemistry》1894,33(1):1-29
Ohne Zusammenfassung 相似文献
949.
James Mc Laughlin Peter Zimmer 《Journal of Mathematical Analysis and Applications》2008,345(2):670-677
We prove a new Bailey-type transformation relating WP-Bailey pairs. We then use this transformation to derive a number of new 3- and 4-term transformation formulae between basic hypergeometric series. 相似文献
950.
A Rota-Baxter operator of weight λ is an abstraction of both the integral operator (when λ=0) and the summation operator (when λ=1). We similarly define a differential operator of weight λ that includes both the differential operator (when λ=0) and the difference operator (when λ=1). We further consider an algebraic structure with both a differential operator of weight λ and a Rota-Baxter operator of weight λ that are related in the same way that the differential operator and the integral operator are related by the First Fundamental Theorem of Calculus. We construct free objects in the corresponding categories. In the commutative case, the free objects are given in terms of generalized shuffles, called mixable shuffles. In the noncommutative case, the free objects are given in terms of angularly decorated rooted forests. As a byproduct, we obtain structures of a differential algebra on decorated and undecorated planar rooted forests. 相似文献