Arsines cyclic

The cyclic arsine (AsMe) reacts with Mn2(CO)jQ at room temperature in daylight to give [Mn2(CO)g(AsMe)5] and at high temperature to give [MnlCOlj-(AsMe) ]2 structures (5) and (6) are proposed in which the metal-metal bond is replaced by bridging arsenic atoms. The crystal structure of [( 0)5-MnAsMc2Cr(CO)5] has been reported. The arsenic atom bridges the two... 

A masked allylic boron unit can be revealed through a transition-metal-catalyzed borylation reaction. For example, a one-pot borylation/allylation tandem process based on the borylation of various ketone-containing allylic acetates has been developed. The intramolecular allylboration step is very slow in DMSO, which is the usual solvent for these borylations of allylic acetates (see Eq. 33). The use of a non-coordinating solvent like toluene is more suitable for the overall process provided that an arsine or phosphine ligand is added to stabilize the active Pd(0) species during the borylation reaction. With cyclic ketones such as 136, the intramolecular allylation provides cis-fused bicyclic products in agreement with the involvement of the usual chairlike transition structure, 137 (Eq. 102). 

A list of more common silver complexing agents includes thiosulfates, thiocyanates, sulfites, cyanides, ammonia and other amines, thiols, thiourea, thioacids, thioethers and alkali halides. Most are not practical as fixing agents because they fail to satisfy all the above criteria. Many find use as silver halide stabilizers (Section 59.2.1.8). These include thiocyanate, thiourea and other thioorganic compounds. These and other complexing agents such as cyclic imides, phosphines and arsines find use in silver halide diffusion transfer processes (Section 59.2.1.6). 

Of the ligands given above, diamines produce cyclic cations. When arsine or sulfide are the donor ligands, the reaction to be employed is the following one. 

In early work, certain seven-membered and larger cyclic arsines were characterized by preparation and isolation of their arsonium salts by quaternization with alkyl halides. Reaction of more elaborate seven-membered cyclic arsines with activated alkyl bromide is shown in Equation (1). The C2-symmetric chiral tertiary arsine 61 reacts with methyl bromoacetate in a pressure tube under microwave irradiation to give the arsonium salt 62 in 71%. The latter was employed in the enantioselective olefination of 4-substituted cyclohexanes via the corresponding stabilized ylide <2002TA2187>. 

During the decade 1996-2005, in this category of heterocycles, the major interest has been the synthesis and reactions of benzarsepins, arsocanes, and cyclic esters of arsenic(m) acids. In contrast, little work has been done in the area of arsine heteromacrocycles with two or more arsenic atoms. Readers are referred to the corresponding sections of CHEC-II(1996) <1996CHEC-II(9)971 > for information concerning earlier works on macrocyclic polyftertiary arsines) and related compounds. 

The opening up of the various synthetic routes between resolved arsonium ions and arsines, particularly for simple non-cyclic compounds, and the laying down of firm stereochemical foundations for interconversions between them, marked the beginning of an era in which chiral tertiary arsines could be designed, synthesized and resolved for a variety of applications in organic synthesis and coordination chemistry. 

Mass spectra of the organometallic compounds of As, Sb and Bi 255 TABLE 10. Organometallic derivatives of cyclic arsines... 

The mass spectra of bimetallic carbonyl metal compounds with cyclic arsine ligands have been discussed (Table 10). Molecular ion peaks are present for the pentamethyl-cyclopentaarsine containing complexes of chromium and tungsten, (AsMe)5[M(CO)]2 (186,188). Their decomposition includes CO and/or M(CO)5 loss giving rise to the ions (AsMe)sM2(CO) + (n = 0-9), (AsMe)sM(CO)/ (n = 0-5), M As Me-" and MAs Me+ (m = 2-4), MjAs Me, M AsMe -" (m = 2-4), MAs (w = 2-5), MAsjCH and AsMOj The latter is the most abundant in the mass spectra . ... 

Primary and secondary arsines react with boron hydrides to give cyclic trimers or polymers (equation 227 ). 

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