Four-, Five-, and Six-Membered Silaplatinacycles Obtained from the Reaction of an Arylallene with Pt(SiHPh₂)₂(PMe₃)₂

Abstract

The reaction of (4-fluorophenyl)allene with Pt(SiHPh 2 ) 2 (PMe 3 ) 2 gives 2-sila-1-platinacyclobutane, 2,5-disila-1-platinacyclopentane, or 4-sila-1-platinacyclohexane, depending on the reaction conditions. All these complexes were characterized by X-ray crystallography and NMR spectroscopy.2,5-Disila-1-metallacyclopentanes 1-10 have attracted attention owing to their unique chemical properties and the important roles they play as an intermediate of transition metal complex catalyzed hydrosilylation and bis-silylation of unsaturated compounds. 3,8 Most of these complexes were prepared by the oxidative addition of two Si-H bonds of 1,2-bis(silyl)alkanes, HSiR 2 CH 2 CH 2 -SiR 2 H, to low-valent transition metal complexes. On the other hand, the reactions of alkene and alkyne with M(SiX 3 ) 2 (PR 3 ) 2 (M ) Pd, Pt; X ) Me, Ph, F) lead to the formation of their 1,2-disilylation products, 11,12 which are closely related to the mechanism of bis-silylation of alkene, allene, and alkyne catalyzed by transition metal complexes. [13][14][15] A similar reaction of alkene or allene with Pt complexes having diorganosilyl ligands would lead to the formation of 1,2-bis(silyl)alkane or 2,5-disila-1-metallacyclopentane as its double oxidative addition product. Actually, Pt(SiHPh 2 ) 2 (PMe 2 Ph) 2 was reported to react with acetylene to afford Pt(SiPh 2 -CHdCH-SiPh 2 )(PMe 2 Ph) 2 . 16 In this paper we report that the reaction of an arylallene with a platinum complex with diphenylsilyl ligands gives not only a new disilaplatinacyclopentane but also four-or five-membered silaplatinacycles depending on the conditions.(4-Fluorophenyl)allene reacts with an equimolar amount of Pt(SiHPh 2 ) 2 (PMe 3 ) 2 17 at room temperature to produce Pt(SiPh 2 C(dCHC 6 H 4 F-4)CH 2 )(PMe 3 ) 2 (1),

Dinuclear Palladium and Platinum Complexes with Bridging Silylene Ligands. Preparation Using (Aminosilyl)boronic Ester as the Ligand Precursor and Their Reactions with Alkynes

“…The CC bond distance of 3b (1.340(5) Å) is comparable with that of the unstrained disilylolefin ( Z )-(PhSCH 2 )Me 2 SiC(Ph)C(H)SiMe 2 (CH 2 SPh) (1.341(10) Å) . The Pt–Si bond distances (2.3705(9) and 2.357(1) Å) and Si–Pt–Si angle (80.56(4)°) are similar to those reported for 2,5-disila-1-platinacyclopentane Pt(SiPh 2 CH 2 C(CHC 6 H 4 F)SiPh 2 )(PMe 3 ) 2 (Pt–Si: 2.365(2) and 2.374(2) Å, Si–Pt–Si: 79.74(7)°) . Complexes 3a and 3b show 1 H NMR peaks due to vinyl hydrogens in the five-membered rings at δ 7.42 and 7.44 flanked with 195 Pt satellite signals ( 3 J Pt–H = 67 Hz).…”

“…Selected Bond Distances (Å) and Angles (deg) of 1, 2, and {M(dmpe)} 2 (μ-SiPh 2 ) 2 (M = Pt, Pd) SiPh 2 )(PMe 3 ) 2 (PtÀSi: 2.365(2) and 2.374(2) Å, SiÀPtÀSi: 79.74(7)°). 18 Complexes 3a and 3b show 1 H NMR peaks due to vinyl hydrogens in the five-membered rings at δ 7.42 and 7.44 flanked with 195 Pt satellite signals ( 3 J PtÀH = 67 Hz). They are at lower magnetic field than the vinyl hydrogen signals of (Z)-Me 3 SiCPhd CHSiMe 3 (δ 6.36) 19 and (o- 20 and are close to that of the disilanickelacyclopentene 21 The 29 Si NMR signals of 3b are observed as two doublets at δ 23.9 and 34.6 flanked with the satellite signals of 195 Pt nuclei (J PtÀSi = 1176 and 1264 Hz, respectively).…”

Photochemical Ring-Contraction of a Tetrasilaferracyclohexane of the (η5-C5H4)Fe(CO)2 System to Trisilaferracyclopentanes

“…Reports concerning disilametallacyclopentanes have appeared in the literature, but there are only two examples of a trisilametallacycle, a trisilairidacyclopentane,9a in which the C atom is a methylene carbon, and a trisilazirconacyclopentane 9b in which the C atom is also part of a fused three-membered ring, N−Zr−C. In both cases the five-membered ring adopts an envelope conformation with dihedral angles of 124.7° and 158°, respectively.…”

An Improved Catalytic System, Pd(PPh3)4/PhCOOH Combined Catalyst, for the Allylation of Carbon Pronucleophiles with Allenes

“…Structure of 5a, 10 5b, 11 5c, 12 5d, 11 were confirmed by comparison with published spectral data. The allenes 1a, 13 1b, 14 1c, 15 and 1d 14 are known in literature. The allene 1e is commercially available and was purchased from Aldrich.…”