Ligand structures acetylenes

Meyers MJ, Sun J, Carlson KE, Marriner A, Katznellenbogen BS, Katzenellenbogen JA (2001) Estrogen receptor-/ potency-selective ligands structure-activity relationship studies of diarylpropionitriles and their acetylene and polar analogues. J Med Chem 44 4230-4251... 

Both MeMn(CO)5 and PhMn(CO)5 react with acetylenes to yield vinyl ketone tetracarbonyl complexes, most likely via a pathway involving CO insertion [Eq. (18)] 14, 36). Reactions of these same alkyls with 1,3-dienes may proceed similarly 16, 95, 96). The chelating ligand o-styryldiphenyl-phosphine (L—L) converts MeMn(CO)j into two products 25) whose structures (XXII and XXIII) were elucidated by X-ray crystallography 24). An unusual migration of COMe onto L—L occurs subsequently to the initial insertion step. 

A number of structures with S-rich dianion ligands have been determined (297-299).831 832 For example, (297) can be synthesized by the reaction of [Ni(CN)4]2 with polysulfide.833 Upon further reaction with CS2 or substituted acetylenes it forms perthiocarbonato and dithiolene complexes, respectively. 

The zinc chloride complex of l-(2-pyridyl)-2-(2-thienyl)ethyne has been structurally characterized by single crystal X-ray diffraction showing the ligand is a monodentate nitrogen donor. The N2Q2 tetrahedral coordination geometry reveals little apparent influence of the acetylene or thiophene groups.110... 

A novel cadmate complex has been formed by the reaction of Cd(NH2>2 with I C=CH in the presence of acetylene in liquid ammonia.250 The potassium salt, K2Gd(CCH)4-2NH3 191, has been structurally characterized. The cadmium center is tetrahedrally coordinated to four acetylide units with which it forms Cd-C bonds of 2.23-2.25 A (Figure 29). The acetylide ligands are 7r-coordinated to two crystallographically distinct potassium ions whose coordination sphere is completed by two ammonia molecules. 

W(n5-C5Me4But)Cl4]2, each in 50% yield (36). The identity of W(q5-C5Me4But)(MeCECMe)Cl2 was proven by an x-ray structural study which showed it to be similar to Ta(ri5-C5Me5)(PhC Ph)Cl2 (37) and related species. The W(V) dimer and W(III) acetylene complex probably form by disproportionation of some intermediate W(IV) complex. What we were most interested in was whether any intermediates not containing a n5-C5Me4Bu ligand could be isolated. 

The structure of Ni4(CO)4(CF3C2CF3)3 79> in which each acetylenic ligand can be considered to provide 6 electrons to the cluster is also shown in Fig. 16. 

Particular organic ligands such as acetylenes and allenes can induce opening of the tetrahedron to give a folded rhombus, which is usually classified as a butterfly structure (Fig. 17). This butterfly structure is also rather surprisingly found for the anion [Fe4(CO)13H] 178, as shown in Fig. 18. 

Although both boronates and alanates react with allylic bromides, aldehydes and C02 to afford allenic products in satisfactory yield, the alanates are more efficient in additions to ketones (Table 9.14). Boronate reagents do not require a B-C alkyl migration for their preparation. Thus the starting acetylene possesses the structural elements of the product. Additionally, the issue of dummy ligands is irrelevant. 

Ni(azobenzene)]had been postulated as containing a ti-N=N bond a structural study confirms this. The structure is shown in (118) the N—N bond length of 1.385(5) A is longer than in the free ligand and very close to the single-bond length. The structure of [Ni(PhC=CPh)(CNBu )2] has also been reported and the acetylene ligand is also bonded side-on to nickel. The co-ordination... 

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