Synthesis and structures of organoantimony compounds containing intramolecular Sb–N interactions

Structural Evidence for Pnictogen-Centered Lewis Acidity in Cationic Platinum-Stibine Complexes Featuring Pendent Amino or Ammonium Groups

As part of our continuing interest in the chemistry of cationic antimony Lewis acids as ligands for late transition metals, we have now investigated the synthesis of platinum complexes featuring a triarylstibine ligand substituted by an o-[(dimethylamino)methyl]phenyl group referred to as Ar^N. More specifically, we describe the synthesis of the amino stibine ligand Ph₂SbAr^N (L) and its platinum dichloride complex [LPtCl]Cl which exists as a chloride salt and which shows weak coordination of the amino group to the antimony center. We also report the conversion of [LPtCl]Cl into a tricationic complex [LHPt(SMe₂)]³⁺ which has been isolated as a tris-triflate salt after reaction of [LPtCl]Cl with SMe₂, HOTf and AgOTf. Finally, we show that [LHPt(SMe₂)][OTf]₃ acts as a catalyst for the cyclization of 2-allyl-2-(2-propynyl)malonate.

Establishing the correlation between catalytic performance and N→Sb donor–acceptor interaction: systematic assessment of azastibocine halide derivatives as water tolerant Lewis acids

A series of organoantimony(iii) halide complexes with a tetrahydrodibenzo[c,f][1,5]azastibocine framework were synthesized and employed as water tolerant Lewis acid catalysts.

Synthesis and non-conventional structure of square-planar Pd(ii) and Pt(ii) complexes with an N,C,N-chelated stibinidene ligand

The N,C,N-chelated stibinidene, ArSb (Ar = C6H3-2,6-(CH[double bond, length as m-dash]NtBu)2), reacts with Pt(ii) compounds [PtCl2L2] resulting in the formation of 1 : 1 complexes, cis-[PtCl2L(ArSb)] (L = Me2S (1), dmso (2)). In contrast, attempts to synthesize similar Pd(ii) complexes failed, resulting only in the formation of elemental palladium. To increase the stability of the ArSb complexes, in particular those containing Pd(ii), the simple auxiliary ligands were replaced with C,N-chelating ones, which led to a set of four compounds of the type [RMCl(ArSb)], where R = C6H4-2-(CH2NMe2) or Fe(η5-C5H4)(η5-C5H3-2-(CH2NMe2)) and M = Pd (3, 5) or Pt (4, 6). Compounds 1-6 were characterized by 1H and 13C{1H} NMR spectroscopy and single-crystal X-ray diffraction analysis, and in the case of ferrocene derivatives 5 and 6, also by cyclic voltammetry. Compounds 2-6 were shown to form rotamers in solution due to the side-on coordination of the ArSb ligand and a hindered rotation around the Sb-Pd(Pt) bond. This process was investigated by 1H-VT-NMR spectroscopy and by DFT computations.

Substitutional disorder in the ionic diorganoanti-mony halide adduct [bromido/chlorido(0.33/0.67)][2-(di-methyl-amino-meth-yl)phen-yl][2-(di-methyl-ammonio-meth-yl)phen-yl]anti-mony(III) 0.75-bromide 0.25-chloride

The title complex, [SbBr(0.33)Cl(0.67)(C(9)H(13)N)(C(9)H(12)N)]Br(0.75)Cl(0.25), exhibits substitutional disorder of both halogen atoms in the asymmetric unit, however, with different occupancies. Thus, the halogen atom bonded to Sb has 0.67 (4) occupancy for Cl and 0.33 (4) for Br, while the anionic halogen atom shows 0.75 (4) occupancy for Br and 0.25 (4) for Cl. An N-H⋯Cl/Br hydrogen bond is established between the cation and the halide anion. The coordination geometry of the Sb center in the cation is distorted pseudo-trigonal-bipyramidal as a result of the strong intra-molecular N→Sb coordination trans to the Sb-Cl/Br bond. The pendant arm on the second ligand is twisted away from the metal center. The compound crystallizes as a racemate, i.e. a mixture of (R(N2),C(Sb1)) and (S(N2),A(Sb1)) isomers with respect to planar chirality induced by the coordinating N atom and chelate-induced Sb chirality. These isomers are associated through C(phen-yl)-H⋯Cl/Br hydrogen bonds, forming a three-dimensional architecture.