Neutral Mononuclear and Binuclear Hexacoordinate Silicon Complexes withSiO5C Skeletons

Abstract

Treatment of the silanes (EtO)3Si(CH2)2SCH2C(O)OSiMe3 and (EtO)3Si(CH2)3OSiMe3 with two molar equivalents of 1‐hydroxy‐2‐pyridone in acetonitrile yielded the neutral hexacoordinate silicon complexes bis[μ‐(3‐thiapentanoato(2−)‐C5,O′:C5′,O)]tetrakis[1‐oxopyridin‐2‐olato(1−)]disilicon(IV) (6) and bis[1‐oxopyridin‐2‐olato(1−)][propanolato(2−)‐C3,O]silicon(IV) (8), respectively. The compounds 6·2CH3CN and 8 were characterized by solid‐state 29Si VACP/MAS NMR spectroscopy, mass spectrometry (FAB MS), and single‐crystal X‐ray diffraction.

Chelation and Stereodynamic Equilibria in Neutral Hypercoordinate Organosilicon Complexes of 1-Hydroxy-2-pyridinone

“…Hexacoordinate cationic silicon complexes of the form [Si­(OPO) 3 ] + X – (X = Cl, FeCl 4 , 1 / 2 SnCl 6 ) were first prepared by Weiss and Harvey and later characterized spectroscopically and structurally by Tacke et al Beyond this homoleptic variety, only a handful of organosilicon complexes bearing the OPO ligand have been reported . Studies involving organosilicon complexes were undertaken here to examine their potential dynamic nature.…”

“…13a,15 Hexacoordinate cationic silicon complexes of the form [Si(OPO) 3 ] + X − (X = Cl, FeCl 4 , 1 / 2 SnCl 6 ) were first prepared by Weiss and Harvey 16 and later characterized spectroscopically and structurally by Tacke et al 17 Beyond this homoleptic variety, only a handful of organosilicon complexes bearing the OPO ligand have been reported. 18 Studies involving organosilicon complexes were undertaken here to examine their potential dynamic nature. The use of electron-donating carbonbased ancillary ligands has proven appropriate for promoting weak Si←OC dative bonding interactions and has led to the discovery of the first well-defined examples of the hemilabile nature of the rigid OPO ligand.…”

Bis(catecholato)silicates: Synthesis and Structural Data

“…[70] In the same vein, other original structures of bis(catecholato)silicates are reported in Scheme 18. For example, Holmes prepared 2,2'-biphenolate silicates in 1990 (Scheme 20A), [71] Tacke replaced the catechol ligand with a 1hydroxy-2-pyridone ligand allowing the formation of a hexacoordinate silicon compound (Scheme 20B), [72] and Spange published an interesting silicate bearing coumarin ligands (Scheme 20C). [73] Studies on the reactivity of such structures would be of particular interest.…”

Crystal structures of tris[1-oxopyridine-2-olato(1−)]silicon(IV) chloride chloroform-d1disolvate, tris[1-oxopyridine-2-olato(1−)]silicon(IV) chloride acetonitrile unquantified solvate, andfac-tris[1-oxopyridine-2-thiolato(1−)]silicon(IV) chloride chloroform-d1disolvate

“…The dihedral angles formed between the O 2 Si chelate and OPO ligands are also similar to those of QOXSIF (9.39, 3.08, and 2.41 ). Structures of monodentate organosilicon OPO complexes include Ph 3 Si(OPO)ÁPh 3 Si(OH)Á0.5n-pentane, Me 3 Si(OPO), and tBu 2 Si( 1 -OPO)( 2 -OPO) (respective CSD refcodes NITRIT, NITROZ, and NITSOA; Kraft & Brennessel, 2014), and of bidentate organosilicon OPO complexes include Ph 2 Si(OPO) 2 , Me 2 Si(OPO)Cl, Ph 3 Si(OPO), Me 2 Si(OPO) 2 , Et 2 Si(OPO) 2 , iPr 2 Si(OPO) 2 , tBu 2 Si( 1 -OPO)( 2 -OPO), and (CH 2 ) 3 Si(OPO) 2 (respective CSD refcodes NISMIN, NISMOT, NITRUF, NITSAM, NITSEQ, NITSOA, NITSIU, and NITSUG;Kraft & Brennessel, 2014), and [Si(OPO) 2 (-CH 2 CH 2 SCH 2 C( O)O)] 2 Á2CH 3 CN and [O(CH 2 ) 3 ]Si(OPO) 2 (respective CSD refcodes UBUWET and UBUWIX; Tacke, Burschka et al, 2001). (I) and (II) have 0.06-0.17 Å shorter Si-O bond lengths and 3-5 larger ligand bite angles than those in chelated R 2 Si(OPO) 2 (R = alkyl, phenyl) complexes, indicating a stronger chelate presumably due, in part, to their cationic character.…”