01624nas a2200241   4500008004100000022001400041245009900055210006900154260000800223520080700231653001901038653003601057653001301093653002501106653001801131100001701149700001501166700001901181700001801200700001901218700001901237856012601256       2019                        eng d  a0947-653900aSaturated N-heterocyclic carbene based thiele's hydrocarbon with a tetrafluorophenylene linker0 aSaturated Nheterocyclic carbene based thieles hydrocarbon with a  cNOV3 a<p>The synthesis of a SIPr [1,3-bis(2,6-diisopropylphenyl)-imidazolin-2-ylidene] derived Kekule diradicaloid with a tetrafluorophenylene spacer (3) has been described. Two synthetic routes have been reported to access 3. The cleavage of C-F bond of C6F6 by SIPr in the presence of BF3 led to double C-F activated compound with two tetrafluoro borate counter anions (2), which upon reduction by lithium metal afforded 3. Alternatively, 3 can be directly accessed in one step by reacting SIPr with C6F6 in presence of Mg metal. Compounds 2 and 3 were well characterized spectroscopically and by single-crystal X-ray diffraction studies. Experimental and computational studies support the cumulenic closed-shell singlet state of 3 with a singlet-triplet energy gap (Delta ES-T) of 23.7 kcal mol(-1).</p>
10aC-F activation10aDensity functional calculations10afluorine10aKekule diradicaloids10asaturated NHC1 aKundu, Gargi1 aDe, Sriman1 aTothadi, Srinu1 aDas, Abhishek1 aKoley, Debasis1 aSen, Sakya, S.  uhttps://library.ncl.res.in/content/saturated-n-heterocyclic-carbene-based-thieles-hydrocarbon-tetrafluorophenylene-linker01780nas a2200205   4500008004100000245010700041210006900148260000800217300000700225490000700232520105500239653002001294653003001314653001801344653002701362100001701389700001901406700001901425856013001444       2022                        eng d00aNucleophilic substitution at a coordinatively saturated five-membered NHC center dot haloborane centre0 aNucleophilic substitution at a coordinatively saturated fivememb  cJUL  a970 v103 a<p>
	In this paper, we have used a saturated five-membered N-Heterocyclic carbene (5SIDipp = 1,3-bis-(2,6-diisopropylphenyl)imidazolin-2-ylidine) for the synthesis of SNHC-haloboranes adducts and their further nucleophilic substitutions to put unusual functional groups at the central boron atom. The reaction of 5-SIDipp with RBCl2 yields Lewis-base adducts, 5-SIDipp center dot RBCl2 [R = H (1), Ph (2)]. The hydrolysis of 1 gives the NHC stabilized boric acid, 5-SIDipp center dot B(OH)(3) (3), selectively. Replacement of chlorine atoms from 1 and 2 with one equivalent of AgOTf led to the formation of 5-SIDipp center dot HBCl(OTf) (4) and 5-SIDipp center dot PhBCl(OTf) (5a), where all the substituents on the boron atoms are different. The addition of two equivalents of AgNO3 to 2 leads to the formation of rare di-nitro substituted 5-SIDipp center dot BPh(NO3)(2) (6). Further, the reaction of 5-SIDipp with B(C6F5)(3) in tetrahydrofuran and diethyl ether shows a frustrated Lewis pair type small molecule activated products, 7 and 8.</p>
10aNHC-haloboranes10anucleophilic substitution10asaturated NHC10atetra-coordinate boron1 aKundu, Gargi1 aTothadi, Srinu1 aSen, Sakya, S.  uhttps://library.ncl.res.in/content/nucleophilic-substitution-coordinatively-saturated-five-membered-nhc-center-dot-haloborane