Organopnictogen(III) bis(arylthiolates) containing NCN-aryl pincer ligands: from synthesis and characterization to reactivity.

Salt elimination reactions between organopnictogen(III) dichlorides, RPnCl 2 [R 1 = 2,6-(Me 2 NCH 2 ) 2 C 6 H 3 , Pn = Sb (1), Bi (2); R 2 = 2,6-{MeN(CH 2 CH 2 ) 2 NCH 2 } 2 C 6 H 3 , Pn = Sb (3), Bi (4); R 3 = 2,6-{O(CH 2 CH 2 ) 2 NCH 2 } 2 C 6 H 3 , Pn = Sb (5), Bi (6)] and 2 equivalents of KSC 6 H 3 Me 2 -2,6 afforded the isolation of a series of new NCN-chelated monoorganopnictogen(III) bis(arylthiolates), RPn(SC 6 H 3 Me 2 -2,6) 2 [R 1 , Pn = Sb (7), Bi (8); R 2 , Pn = Sb (9), Bi (10); R 3 , Pn = Sb (11), Bi (12)]. Compounds 7 and 8 are unstable upon exposure to a dry O 2 atmosphere and their aerobic decomposition yields the monoorganopnictogen(III) oxides, cyclo -[2,6-(Me 2 NCH 2 ) 2 C 6 H 3 Pn(μ-O)] 2 [Pn = Sb (13), Bi (14)] with concomitant formation of the corresponding disulfide, ArS-SAr (Ar = C 6 H 3 Me 2 -2,6). The oxidative addition of elemental sulfur or selenium to 7 undergoes a similar reaction path and gives stable heterocyclic species cyclo -[2,6-(Me 2 NCH 2 ) 2 C 6 H 3 Sb(μ-E)] 2 [E = S (15), Se (16)]. The reaction of 12 with I 2 (1 : 1 molar ratio) gives the diiodide [2,6-{O(CH 2 CH 2 ) 2 NCH 2 } 2 C 6 H 3 ]BiI 2 (17), along with the S-S oxidative coupling by-product, ArS-SAr. The use of an excess of iodine affords the crystallization of a 2 : 1 iodine adduct of 17 (17·0.5I 2 ), built through halogen bonding. All new compounds were characterized by multinuclear NMR spectroscopy and ESI-MS as well as single crystal X-ray diffraction (except compounds 9 and 10).