Synthesis and structural characterisation of neutral pentacoordinate silicon(iv) complexes with a tridentate dianionic N,N,S chelate ligand

Abstract

A series of novel neutral pentacoordinate silicon(IV) complexes with SiClSN(2)C, SiBrSN(2)C, SiSN(3)C, SiSON(2)C, SiS(2)N(2)C, SiSeSN(2)C and SiTeSN(2)C skeletons (compounds 1-12) was synthesised, starting from PhSiCl(3), PhSiBr(3), PhSi(NCO)(3), MeSiCl(3) or C(6)F(5)SiCl(3). Compounds 1-12 contain (i) a tridentate dianionic N,N,S chelate ligand (derived from 2-{[(pyridin-2-yl)methyl]amino}benzenethiol), (ii) a phenyl, methyl or pentafluorophenyl group and (iii) a monodentate monoanionic ligand (Cl, Br, NCO, NCS, N(3), OS(O)(2)CF(3), OPh, SPh, SePh, TePh). The pentacoordinate silicon(iv) complexes 1-12 were characterised by elemental analyses, NMR spectroscopic studies in the solid state and in solution and crystal structure analyses. These experimental investigations were complemented by computational studies.

Neutral Pentacoordinate Silicon(IV) Complexes with a Tridentate Dianionic O,N,O or N,N,O Ligand, an Anionic PhX Ligand (X = O, S, Se), and a Phenyl Group: Synthesis and Structural Characterization in the Solid State and in Solution

“…The isotropic 29 Si chemical shifts in solution for 5b (PhS, O , N , O ), 6b (PhS, N , N , O ), 5c (PhSe, O , N , O ), and 6c (PhSe, N , N , O ) (Table 5) indicate that these compounds exist as pentacoordinate silicon(IV) complexes in solution as well; however, the shifts in the solid state and in solution differ by about 5 ppm. The magnitude of this shift difference is not unusual and was already reported in one of our earlier publications and discussed extensively with support of computational studies 7e. In this context it is also interesting to note that the solid‐state 29 Si chemical shifts of the two crystallographically independent molecules of 6a , which have very similar structures, differ by 3.0 ppm (Table 5, Figure 4).…”

Pentacoordinate Silicon Complexes with N‐(2‐pyridylmethyl)­salicylamide as a Dianionic (ONN′) Tridentate Chelator

“…With reference to the complexes reported by Tacke et al (Scheme , bottom right),11 the pyridine donor influence appears to be pronounced in their complexes, with Si–N(pyridine) bond lengths ranging between 1.970(1) Å (for R / X =Ph/O 3 SCF 3 ) and 2.029(2) Å (for R / X = Me/SePh). These slightly shorter bond lengths can be attributed to various differences in the substitution pattern, i.e., a more electronegative substituent in the equatorial plane, an additional five‐membered chelate in the complex and, last but not least, the sulfur atom trans to the pyridine donor.…”

“…Gómez et al and Holmes et al already reported on neutral pentacoordinate diorganosilicon complexes with an additional pyridine donor moiety bound to the ligand backbone via a flexible alkyl group, but they needed to clamp the pyridine donor to silicon by using two anionic anchors in 2, 6‐position of the pyridine (Scheme , bottom left) 10. Recently, Tacke et al reported on pentacoordinate monoorganosilicon complexes with a pyridine donor moiety, which was anchored to silicon via only one –CH 2 –N– arm in 2‐position, which offers rotational degrees of freedom, thus not forcing the pyridine to bind to silicon (Scheme , bottom right) 11…”

The Syntheses and Crystal Structures of the First Disiloxane‐1,3‐dithiol and Its Cadmium Complex

“…[36][37][38][39][40] Sulfur analogs of Si-O species include cyclosilthianes, [7,[41][42][43][44][45][46][47][48] silanethiols (characterized mainly as their metal salts), [8,15,16,[36][37][38][39][40][49][50][51][52][53][54][55][56][57][58][59][60] silanedithiols, [14,61,62] silyl sulfides, [63][64][65] di-and polysulf-ides, [66][67][68][69][70] and other rare species. [20,[75][76][77] In this communication, we report the syntheses of bis-1,3-[bis(2,6-diisopropylphenoxy)]disiloxane-1,3-dithiol (1), which is the first sulfur analog of disiloxane-1,3-diol, and its cadmi...…”