Synthesis of heteroboroxines with MB2O3 core (M = Sb, Bi, Sn)—an influence of the substitution of parent boronic acids

Abstract

The synthesis and structure of stiba-, stanna- and bismaheteroboroxines of a general formula L(E)M[(OBR)2O] supported by a N,C,N-chelating ligand L [where L = C6H3-2,6-(CH2NMe2)2, M, E = Sb, lone pair or Sn, Ph or Bi, lone pair] is reported. The target compounds are prepared by straightforward one-step reactions between oxides (LMO)2 (M = Sb or Bi) or organotin(iv) carbonate L(Ph)Sn(CO3) with four or two molar equivalents of corresponding organoboronic acid. All compounds were characterized with the help of elemental analysis, multinuclear NMR spectroscopy and on several occasions the molecular structure was determined using single-crystal X-ray diffraction analysis. The influence of both the substitution of the parent organoboronic acid and the central atom used on the feasibility of the condensation reaction was addressed. Furthermore, several heteroboroxines containing nitrogen donor functionality (i.e. NH2, NMe2, CN or 4-pyridyl) included in the boronic acid residue were synthesized and characterized with the aim to prepare boroxine-based covalent frameworks (through intermolecular N→B interactions) containing metal atoms in their structures. Although no such intermolecular bonding was detected in solution of these compounds, it was shown that the organotin(iv) heteroboroxine substituted by 4-pyridyl group forms an infinite polymeric chains via N→B interactions in the solid state. This polymer collapsed back to monomeric units upon dissolution.

Applications of boroxide ligands in supporting small molecule activation by U(iii) and U(iv) complexes

“…Boroxines are rigid bidentate ligands which have drawn attention recently, mostly by forming complexes of main group elements, e.g. for Al; [38][39][40] Sn, Sb and Bi; [41][42][43][44][45][46][47] but also for transition metals such as Mn, 48 Au 37,49 and Pt. 50 Single crystals of 5 m and 6 m were obtained by slow diffusion of hexanes into a benzene solution.…”

Synthesis of Cyclic and Cage Borosilicates Based on Boronic Acids and Acetoxysilylalkoxides. Experimental and Computational Studies of the Stability Difference of Six- and Eight-Membered Rings

“…Recently, the donor–acceptor N→B bonds were successfully used for the construction of macrocycles, cagelike compounds, or one-dimensional (1D), two-dimensional (2D), or 3D networks. − However, a clear majority of these adducts is based on boronic esters or boroxine rings, and only a handful of compounds with B–O–Z (Z ≠ B, C, H) moiety were reported containing N→B bonds. These are (N,O-κ 2 -H 2 N­(CH 2 ) 3 O)­(RO)­B­(μ-O)­SiPh n Me 3– n (R = Ph, n = 0, 1, 2, 3; R = t Bu, n = 1, 2, 3), , [ t BuSi­{O­(PhB)­O} 3 Si t Bu] n ·L (L = pyridine, n = 1; L = Me 2 NCH 2 CH 2 NMe 2 , n = 2), and {2,6-(CH 2 NMe 2 ) 2 -C 6 H 3 }­Sn­(OBPy) 2 (μ-O) (py = pyridine) . Therefore, we became interested in the coordination of boron atoms in the borosilicate rings with an organic diamine.…”

N→Sn-Coordinated Stannaoxidoborates Containing a SnB4O6 Unit

“…The treatment of organotin­(IV) carbonate (L- k 3 N 2 C )­PhSnCO 3 ( 1 ) with organoboric acids RB­(OH) 2 at a 1:2 molar ratio provided the corresponding organotin­(IV) stannaboroxines (L- k 3 N 2 C )­PhSn­(O 3 B 2 R 2 ), where L = [2,6-(Me 2 NCH 2 )­C 6 H 3 ] − and R = Ph ( 2 ), 4-Br-Ph ( 3 ), 3,5-(CF 3 ) 2 -Ph ( 4 ), and 4-CHO-Ph ( 5 ) (Scheme ). Compounds 2 , 3 , and 5 were prepared and characterized according to the literature . Compound 4 was characterized by NMR spectroscopy.…”

“…Recently, it was demonstrated that the boron atom of the boroxine ring can be easily substituted by metal atoms to give a variety of metallaboroxines of the general formula M­(O 3 B 2 R 2 ), where M is Pt, Al, Sb, Bi, or Sn . Later on, we have provided the easy preparation of new stannaboroxines of the general formula (L- k 3 N 2 C )­PhSn­(O 3 B 2 R 2 ), where L is 2,6-bis­(dimethylaminomethy)­phenyl and R is an aryl substituent, respectively, containing a six-membered SnB 2 O 3 ring . Our extensive research in the field of stannaboroxine systems has also provided the synthesis of a new type of stannaoxidoborate, H­[(L- k 2 NC )­SnB 4 O 6 R 4 ], derivatives of the pentaborates [B 5 O 6 R 4 ] − in which the central boron atom is substituted by a tin atom.…”