Ligands hybrid

Another exceUent method for preparing tertiary stibines involves the interaction of an organostibide and an alkyl or aryl haHde (91,92). This method is of particular value in preparing un symmetrical tertiary stibines. For example, an interesting hybrid ligand has been obtained by the foUowing reaction carried out in Hquid ammonia (93) ... 

Eigure 3 represents an illustrative biological application an Asp Asn mutation, carried out either in solution or in complex with a protein [25,26]. The calculation uses a hybrid amino acid with both an Asp and an Asn side chain. Eor convenience, we divide the system into subsystems or blocks [27] Block 1 contains the ligand backbone as well as the solvent and protein (if present) block 2 is the Asp moiety of the hybrid ligand side chain block 3 is the Asn moiety. We effect the mutation by making the Asn side chain gradually appear and the Asp side chain simultaneously disappear. We choose initially the hybrid potential energy function to have the form... 

Figure 3 Mutation of a ligand Asp into Asn in solution and bound to a protein, (a) Thermodynamic cycle, (b) Dual topology description a hybrid ligand with two side chains. Blocks are used to define the hybrid energy function [Eq. (14)]. Only the ligand is shown the environment is either solvent or the solvated protein, (c) Single-topology description.

Whereas the mono- and the S/S-dithioether moieties have been used to date, the 1,3-dithianyl motif was used for the first time in 2005 by Ricci et al. as a new hybrid ligand in asymmetric catalysis. Hence, a series of new chiral oxazoline-1,3-dithianes have been successfully applied to the copper-catalysed conjugate addition of ZnEt2 to enones (Scheme 2.16). The expected products were obtained in almost quantitative yields and enantioselectivities of up to 69% ee. 

Using a triazole-/pyrimidine-containing hybrid ligand, terminally coordinated in a thiocyanate-bridged copper(II) dimer, Haasnoot et al. reported250 the structure of the f3 isomer of complex (288), revealing that the Cu-SCN distance is relatively short compared to other Cu-SCN... 

Subsequently, Burgess79 prepared a series of hybrid ligands (27a-c) (Figure 3) which were chiral not only in the carbon backbone like (R, R)-DIOP 25 but also at phosphorus, like DIPAMP. 

Subsequently, it was shown that rhodium complexes derived from diphosphi-nites, diphosphonites, and diphosphites - as well as hybrid ligands - are similarly active and selective to diphosphines [46 i],... 

An unusual carbene-thioether hybrid ligand 174 was synthesized and applied in the rhodium-catalyzed asymmetric hydrogenation of dimethyl itaconate by Chung and co-workers however, the selectivity and activity were low (Table 27.7, entry 34) [135]. 

P,A/-ligand. These hybrid ligands have been found to afford superior results in various metal-catalyzed processes. In addition, their modular architecture enables systematic fine tuning of a generalized structure to suit a specific process. 

Complexes of the type [PdX L] (X = Cl, Br, I, or SCN) and PdL Y (Y = Cl, Br, I, SCN, or CIO ) have been prepared with the hybrid ligands (68)—(70). I.r. data confirm that the [PdX2L] compounds are square-planar with bidentate L. However, depending on the nature of Y, the PdL Yj species exhibit a variety of four-, five-, and six-co-ordinate forms containing both bidentate and unidentate (As bonded) hybrid ligands. ... 

PPACK-NAPAP hybrid ligand (thick lines) generated by CCLD starting from the functional groups of PPACK and NAPAP (thin lines). The amide linker connecting the piperidine in 3-position to the D-Phe was created by CCLD. 

Among the earliest multidenate undelocalized amido ligands to be investigated in a systematic way were hybrid ligands involving amido and phosphine donor sites such as D-F that were... 

Aluminum—tetradentate ligand catalyst system, in epoxide homopolymerization, 11, 601 Aluminum(I) tetrahedra, synthesis, 9, 262 Aluminum(III)-tin exchange, process, 9, 265 Aluminum-transition metal bonds, characteristics, 9, 264 Amavadine, for alkane carboxylations, 10, 234—235 Ambruticin S, via ring-closing diene metathesis, 11, 218 Amide-allenes, cyclizations, 10, 718 Amide ether complexes, with Zr(IV) and Hf(IV), 4, 783 Amide hybrid ligands, in organometallic synthesis, 1, 64 Amides... 

Crown-5-triarylphosphine hybrid ligand, preparation, 8, 2 Crystal engineering... 

So reported the di-lithium methandiide complex 23 which employs the hybrid ligand used in 12.23 Interestingly, complex 23, which is dimeric and constructed around a Li4C2 core, was found to crystallise with the two imino nitrogens up and the two thio sulfurs down which enables a molecule of THF to coordinate to the bis-thio-coordinated lithium centre, as in 21 and 22. 

Building on their recent work with group 4 elements using their Cp-pendant pyrazolide hybrid ligands, Otero and coworkers have now turned their attention to rare earths. Simple methathesis of [Li(bpzcp)(THF)] [bpzcp = 2,2-... 

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