Synthesis of Tellurasila Cycles Containing an Annelated Dicarba‐<i>closo</i>‐dodecaborane(12) Unit: Structure of a 1,4‐Ditellura‐2,3‐disilacyclohexane Derivative

Wrackmeyer, Bernd; Klimkina, Elena V.; Milius, Wolfgang

doi:10.1002/ejic.201201124

Cited by 5 publications

References 93 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

1,3,2‐Dioxaphospholanes with an Annelated 1,2‐Dicarba‐closo‐dodecaborane(12) Unit: Formation and Dimerization

2013

Self Cite

View full text Add to dashboard Cite

By using 1,2-hydroxy-1,2-dicarba-closo-dodecaborane(12) and the corresponding dilithium salt [1,2-(LiO) 2 -1,2-C 2 B 10 H 10 ] for the synthesis of 1,3,2-dioxaphospholanes, it was shown that these species are short-lived with few exceptions. The phosphorus halides undergo disproportionation reactions towards phosphite derivatives, whereas the P-organo-substituted five-membered rings dimerize to give tenmembered rings. Even the P-diethylamino and the P-ethoxy compounds dimerize slowly. Dimerization is the favored process when using the dilithium salt together with ether. The reactions were monitored by multinuclear magnetic resonance spectroscopy ( 1 H, 11 B, 13 C, 31 P NMR). The gas-phase structures were optimized by DFT methods [B3LYP/6-Scheme 2. Transformation of ortho-carborane-diol 1 into the dilithiated derivatives.Scheme 3. Reaction of 2 with phosphorus trihalides. moval of the volatile materials in a vacuum (Scheme 3). Frequently, a small amount of compound 5 was present, because of partial hydrolysis of 4. Some NMR spectroscopic data of 3-5 could be obtained (Table 1). The equilibrium is slowly shifted towards 4 even in the absence of PX 3 , and as the result of the small scale of the preparative work, hydrolysis cannot be avoided and might even become dominant (see Figure 1). In the case of iodide 3c, the 31 P NMR spectra of the reaction solution clearly indicate the existence of 6, which after some time is converted completely into 4, accompanied by 5. In the cases of the reaction solutions that contain chloride 3a and bromide 3b, there are weak 31 P NMR spectroscopic signals of small intensity that might belong to intermediates analogous to 6. Signals for an appreciable amount of oxidized products could not be observed in the 31 P NMR spectra.All attempts to obtain the P-organo-substituted 1,3,2-dioxaphospholanes 7-10 (Scheme 4) revealed their formation followed by rather fast (a few hours) conversion, mainly into dimers 11-14, together with small amounts of other products, possibly oligomers, as readily shown by 31 P NMR spectroscopy (see also Tables 1 and 2). The formation of 7-10 is typically accompanied by noncyclic deriva-Eur.

show abstract

1,3,2‐Dioxaphospholanes with an Annelated 1,2‐Dicarba‐closo‐dodecaborane(12) Unit: Formation and Dimerization

2013

Self Cite

View full text Add to dashboard Cite

show abstract

1,3,2‐Diselena‐ and 1,3,2‐Ditelluraphospholanes with an Annelated 1,2‐Dicarba‐closo‐dodecaborane(12) Unit

2014

View full text Add to dashboard Cite

The exchange reactions of phosphorus dihalides RPX2 [R = iPr, cyclohexyl (Cy), tBu, (3,5‐Me2‐C6H3)CH2, Ph; X = Cl, Br], EtOPCl2, Et2NPCl2, Cl2PCH2PCl2, and Cl2PCH2CH2PCl2 with 2,2‐dimethyl‐4,5‐[1,2‐dicarba‐closo‐dodecaborano(12)]‐1,3‐diselena‐2‐silacyclopentane provide a straightforward route to 1,3,2‐diselenaphospholanes. Some tellurium analogues were prepared from the dilithium salt [1,2‐(LiTe)2‐1,2‐C2B10H10] and were more difficult to characterize. For the selenium compounds, some of the P‐organosubstituted five‐membered rings dimerize to give ten‐membered rings, most readily with the more bulky alkyl groups such as tBu. This was not observed for the tellurium compounds. The conformations of the five‐membered rings were studied by NMR spectroscopy and DFT methods. Striking structural differences were clear for the 2‐phenyl‐1,3,2‐diselenaphospholane derivative in solution and in the solid state. All reactions were monitored by multinuclear magnetic resonance spectroscopy (1H, 11B, 13C, 31P, 77Se, and 125Te NMR), and solution‐state structures could be proposed. Remarkably large secondary isotope effects as isotope‐induced chemical shifts 2Δ12/13C(31P) exerted by the carborane carbon atoms were observed; this is apparently a special property of the five‐membered ring. The gas‐phase structures were optimized by DFT methods [B3LYP/6‐311+G(d,p) level of theory], and the NMR parameters were calculated. Two 1,3,2‐diselenaphospholanes and one dimer were characterized by X‐ray analysis.

show abstract

Icosahedral Carboranes

Grimes¹

2016

Carboranes

View full text Add to dashboard Cite

Synthesis of Tellurasila Cycles Containing an Annelated Dicarba‐closo‐dodecaborane(12) Unit: Structure of a 1,4‐Ditellura‐2,3‐disilacyclohexane Derivative

Cited by 5 publications

References 93 publications

1,3,2‐Dioxaphospholanes with an Annelated 1,2‐Dicarba‐closo‐dodecaborane(12) Unit: Formation and Dimerization

1,3,2‐Dioxaphospholanes with an Annelated 1,2‐Dicarba‐closo‐dodecaborane(12) Unit: Formation and Dimerization

1,3,2‐Diselena‐ and 1,3,2‐Ditelluraphospholanes with an Annelated 1,2‐Dicarba‐closo‐dodecaborane(12) Unit

Icosahedral Carboranes

Contact Info

Product

Resources

About