A. Pidcock

Synthesis of organotrialkylstannanes. The reaction between organic halides and hexaalkyldistannanes in the presence of palladium complexes

Abstract The aryl halides YC 6 H 4 X (X = Br or I) have been shown to react with the distannanes (R 3 Sn) 2 (R = n-Bu or Me) in toluene in the presence of [Pd(PPh 3 ) 4 ] or [PdBr 2 (PPh 3 ) 2 ] to give the compounds YC 6 H 4 SnR 3 for (a) R = n-Bu, Y = H, p-OMe, o -Me, p -Me, m -Cl, p -Cl, m -CN, p -COCH 3 and m -NO 2 , and (b) R = Me, Y = H, p -OMe, p -Me, p -CN, p -COCH 3 , m -NO 2 and p -NO 2 . Benzyl halides YC 6 H 4 CH 2 X (X = Cl or Br) similarly give YC 6 H 4 CH 2 SnR 3 for (a) R = n-Bu, Y = H, m -OMe, p -OMe, m -Cl, m -CN, and m -NO 2 , and (b) R = Me, Y = m -Cl, m -CN, p -CN and m -NO 2 . These reactions are of special value as preparative procedures in cases in which Grignard or organolithium reagents cannot be used. Allyl chloride and bromide were likewise shown to react with (n-Bu 3 Sn) 2 to give CH 2 CHCH 2 SnBu 3 , but n-BuCl and n-BuBr gave only a trace of n-Bu 4 Sn. The mixed dimetallo species n-Bus 3 SnSiMe 3 was shown to react with aryl bromides YC 6 H 4 Br (X = H, p -OMe, p -Me, or p -Cl) to give the arylsilicon compounds YC 6 H 4 SiMe 3 , with no aryltin products.

Further studies on reactions of organic halides with disilanes catalysed by transition metal complexes

Abstract The interaction of a range of organic halides with (Cl3Si)2 or (Me3Si)2 in the presence of a variety of transition metal catalysts (very predominantly Pd0 or PdII complexes) have been examined. PhSiMe3 was formed from PhCl[m.y., 15%] (m.y. - maximum yield), PhBr (m.y., 92%, with [PdL2Br2] as catalyst (L - PPh3)), and (contrary to earlier reports) PhI (m.y. 51%, with [PdL2I2]). MeSiCl3 was formed from MeBr (m.y., 78% with [PdL4]) and MeI (m.y., 91% with [PdL4]), and EtSiCl3 from EtBr (m.y., 49%, with [PdL2“Br2]; L” - P(C6H4OMe-p)3) and EtI (m.y. 45%, with [PdL4]). Me4Si was satisfactorily formed from MeBr (m.y. 42%, with [PdL4]). Evidence was obtained for the formation of Me3SiCF3 from CF3I. Very poor yields of XC6H4CH2SiMe3 were obtained from XC6H4CH2Br (X - H orp-Me) (with X - H some PhSiMe3 was formed), butp-O2NC6H4CH2SiMe3 was formed in 48% yield fromp-O2NC6H4CH2Cl with [PdL“4] as catalyst. PhCOSiMe3 was formed from PhCOCl (m.y. 52% with [PdL2I2]. The nickel complex [NiL4] was moderately effective as a catalyst for reactions between (Cl3Si)2 and MeBr, EtBr, or PhCH2Br. The new complex [PdL2(SiCl3)2] was prepared by treatment of [PdL4] with (Cl3Si)2 or Cl3SiH, and shown to catalyse the reaction between MeBr and (Cl3Si)2.

Some platinum complexes containing chelating bis(silyl) ligands

Summary The dihydrides o -(HMe 2 Si) 2 C 6 H 4 and o -(HMe 2 Si)C 6 H 4 CH 2 SiMe 2 H react with [PtL 2 (C 2 H 4 )] (L=PPh 3 ) at room temperature to give the 5- and 6-membered cyclic bis(silyl) complexes [Pt(SiMe 2 C 6 H 4 SiMe 2 - o )L 2 ] (1), and [Pt{SiMe 2 C 6 H 4 -(CH 2 SiMe 2 )- o } L 2 ] (II), respectively. The disiloxane (HPh 2 Si) 2 O reacts with [Pt 2 (C 2 H 4 )] to give a 4-membered cyclic species [Pt(SiPh 2 OSiPh 2 )L 2 ] at 45° ; (HMe 2 -Si) 2 O gives the hydrido(silyl) complex cis -[PtH(SiMe 2 OSiMe 2 H)L 2 ] at 45°, but the latter cyclises at 75° to give [Pt(SiMe 2 OSiMe 2 )L 2 ]. The dihydrides o -(HMe 2 SiCH 2 ) 2 C 6 H 4 and HMe 2 Si(CH 2 ) 4 SiMe 2 H, which could, in principle, give complexes with 7-membered rings, in fact give only cis -[PtH {SiMe 2 CH 2 C 6 H 4 (CH 2 -SiMe 2 H)- o } L 2 ] and cis -[PtH{SiMe 2 (CH2)4SiMe 2 H}L 2 ] on reaction with [PtL 2 -(C 2 H 4 )]. Complexes (I) and (11) react with 1,2-bis(diphenylphosphino) ethane (Diphos) to give the doubly-chelated species [Pt(SiMe 2 C 6 H 4 SiMe 2 - o ) (Diphos)] and [Pt-{SiMe 2 C 6 H 4 (CH 2 SiMe 2 )- o } (Diphos)] respectively. Both silicon atoms in complexes (I) and (II) are displaced from platinum by bromine, methyl iodide, or phenylacetylene. The complexes cis -[PtH(SiPh 2 CH 2 CH=CH 2 )L 2 ] and cis -[PtH(SiMe 2 C≡CSiMe 2 H)L 2 ] react with methyldiphenylsilane to give cis -[PtH(SiPh 2 Me)L 2 ].

Some unusual methylations and arylations of platinum(II) chlorides by organotin compounds the 13C NMR spectra of bis-aryl(η-cycloocta-1,5-diene)platinum(II) complexes

Abstract Treatment of [Pt(COD)Cl2] with SnMe4 in Cl2CHCHCl2 at 100°C has been shown to give [Pt(COD)(Me)Cl] in 59% yield, while use of Me2SO as solvent gives [PtMe2(Me2SO)2], and hence [PtMe2(PPh3)2] in 50% yield. Interaction of [Pt(COD)Cl2] with Sn(C6H4SMe-p)Me3 gives the polymeric species [Pt(C6H4SMe-p)2]n. Treatment of [Pt(COD)Cl2] with 1-trimethylstannyl- or bis(1,1′-trimethylstannyl)-ferrocene gives [Pt(COD)(C5H4FeC5H5)Cl] or the ferrocenyl-bridged[Pt(COD)Cl(C5H4FeC5H4)Cl(COD)Pt]. Treatment of trans-[Pt2Cl4(PEt3)2] with Sn(C6H4Me-p)Me3 readily brings about replacement of the terminal chloride ligands to give [Pt2(C6H4Me-p)2Cl2(PEt3)2]. The 13C NMR spectra of various [Pt(COD)(C6H4X)2] complexes are reported, and also values of the longest wavelength maximum, λmax, in the visible spectrum of [Pt(C6H4X)2(BIPY)]. The values of the 13C chemical shifts for the olefinic protons of the COD complexes given an excellent linear correlation with σ° values of the X groups, and with the values of λmax for the BIPY complexes.

Oxidative addition of tin(IV) compounds to ethylene bis(triphenylphosphine)platinum

Abstract Reactions between [Pt(C 2 H 4 )(PPh 3 ) 2 ] and organotin halides have been investigated. With SnPh 2 Cl 2 the product of insertion into the SnC bond, cis -[PtPh(SnPhCl 2 )(PPh 3 ) 2 ], was obtained, whereas SnMe 2 Cl 2 , SnPhCl 3 , SnMeCl 3 and SnCl 4 gave products of insertion into the Sn-Cl bond, viz. cis - and trans -[PtCl((SnCl n R 3-n )(PPh 3 ) 2 ]. The products were characterised by 31 P - { 1 H} NMR spectroscopy. Compounds of similar stoichiometry [PtR(SnCl 3 )(PPh 3 ) 2 ] were examined for purposes of comparison and were obtained from SnCl 2 and the corresponding chloro complexes. The compounds cis and trans [PtCl(SnCl 3 ) (PPh 3 ) 2 ] were obtained both by the oxidative-addition reaction and the SnCl 2 insertion route. A wide variety of similar products were obtained with organotin chlorides and bromides. Competition experiments indicated an order of reactivity in the oxidative addition reaction SnMe 4 4 3 Cl 3 Cl, SnMeCl 2 2 Cl 2 , SnMeCl 3 3 4 . The presence of radicals in the reaction mixture was not detected by radical transfer or spin-trapping experiments.

Hydrosilylation of carbonyl compounds catalysed by ruthenium complexes

Summary The ruthenium complex [RuCl2(PPh3)3] catalyses the reaction of triethylsilane with ketones, RR′CO, and aldehydes, RCHO, to give the hydrosilylation products RR′CHOSiEt3 and RCH2OSiEt3, respectively, but it is not as effective a catalyst as [RhCI(PPh3)3]. The complex [RuCIH(PPh3)3] was obtained by treatment of [RuCl2(PPh3)3] with triethylsilane, and [RhCl(PPh3)2(CO)] was isolated from reaction between p-methoxybenzaldehyde and triethylsilane catalysed by [RhCl(PPh3)3].

The preparation of hydrido(silyl)bis(triphenylphosphine)platinum(II) complexes from bis(triphenylphosphine)platinum-ethylene and silicon hydrides

Abstract The reaction between [PtL 2 (C 2 H 4 )] (L = PPh 3 ) and a variety of organosilicon hydrides, R 3 SiH, has given the complexes [PtH(SiR 3 )L 2 ], (I), where R 3 Si = Ph 3 Si, Ph 2 MeSi, Ph 2 HSi, PhMe(CH 2 CH)Si, Et 3 Si, (EtO) 3 Si, and (Me 3 SiO) 2 MeSi; the hydride Me 2 ClSiH, however, gives the bis(silyl) complex [Pt(SiMe 2 Cl) 2 L 2 ]. The acetylene complexes [PtL 2 (PhCCX)] (X = H or Ph) also react, though less readily, with Ph 2 MeSiH to give [PtH(SiMePh 2 )L 2 ]; this complex reacts with an excess of PhCCX to regenerate the [PtL 2 (PhCCX)]. The complexes of type (I), which are thought to have cis configurations, are stable in the air as solids, but unstable in benzene solution. The hydrides Cl 3 SiH and MeCl 2 SiH react with [Pt(PPh 2 Me) 4 ] to give [Pt(SiCl 3 ) 2 (PPh 2 Me) 2 ] and [Pt(SiMeCl 2 ) 2 (PPh 2 Me) 2 ], respectively.

Preparation of diphenylphosphido- and phenylthio-bridged dinuclear platinum(II) complexes by use of trimethyl(diphenylphosphino)- and trimethyl(phenylthio)-silane☆

Abstract The complexes [Pt 2 Cl 2 (μ-Cl) 2 L 2 ] (L = triorganophosphine) react with 2 molar proportions of SiMe 3 (PPh 2 ) in tetrahydrofuran or CH 2 Cl 2 at room temperature to give the corresponding phosphido-bridged complexes trans -[Pt 2 Cl 2 (μ-PPh 2 ) 2 L 2 ]. The same products are formed, in lower yield, by treatment of cis -[PtCl 2 L 2 ] complexes with 1 molar proportion of SiMe 3 (PPh 2 ), and the arsine complex trans -[Pt 2 Cl 2 (μ-PPh 2 ) 2 (AsEt 3 ) 2 ] is produced analogously from cis -[PtCl 2 (AsEt 3 ) 2 ]. The corresponding reaction with trans -[Pt(Cl)H(PEt 3 ) 2 ] gives trans -[Pt 2 H 2 (μ-PPh 2 ) 2 (PEt 3 ) 2 ]. Treatment of trans -[Pt 2 Cl 2 (μ-Cl) 2 L 2 ] complexes with SiMe 3 (SPh) gives cis -[Pt 2 Cl 2 (μ-Cl)(μ-SPh)L 2 ], trans -[Pt 2 Cl 2 (μ-SPh) 2 L 2 ], or trans -[Pt 2 (SPh) 2 (μ-SPh) 2 L 2 ] depending upon the molar proportion of SiMe 3 (SPh) and the temperature used, while cis -[PtCl 2 L 2 ] gives trans -[Pt(SPh) 2 L 2 ]. Ethylation of trans -[PtCl 2 (μ-SPh 2 )L 2 ] (L = P-n-Pr 3 ) with [OEt 3 ]BF 4 appears to give the chloride-bridged trans -[Pt 2 (μ-Cl) 2 (SEtPh) 2 L 2 ][BF 4 ] 2 .

Square planar platinum(II) complexes. Crystal structures of cis-bis(triphenylphosphine)hydro (triphenylstannyl)platinum(II) and cis-bis(triphenylphosphine)hydro(triphenylsilyl)platinum(II)

Abstract The complexes cis-[PtH(SnPh3)(PPh3)2], cis-[PtH(Sn(C6H4Me-p)3)(PPh3)2], cis-[PtH{Sn(C6H4 Me-p)3}(DIOP)], and cis-[PtH(SiPh3))PPh3)2] have been prepared, and the crystal structures of cis-[PtH(SnPh3) (PPh3)2] and cis-[PtH(SiPh3)(PPh3)2] have been determined. Both of these complexes exhibit distorted square-planar geometry at platinum. In the tin complex, the PtP bonds are almost equal in length, but in the silicon complex, the PtP bond trans to silicon is significantly longer than that cis to silicon, in accord with the larger trans influence of silyl ligands.

The reaction of bis(phenyldimethylphosphine)bis(diphenylsilyl)platinum(II) with acetylenes

Summary The complex cis-[Pt(SiPh2H)2L2] (L PhMe2P), I, reacts with acetylene to give a product believed to be the chelate [Pt(SiPh2CH CHSiPh2)L2], II; phenyl-, p-bromophenyl-, and p-fluorophenyl-acetylene give analogous products. On treatment with Ph2PCH2CH2PPh2 (dppe), II gives [Pt(SiPh2CH CHSiPh2)(dppe)]. The corresponding saturated compounds [Pt(SiPh2CH2CH2SiPh2)L2] and [Pt(SiPh2CH2CH2SiPh2)(dppe)] and the vinylic [Pt(SiPh2Me)2(Ph2PCH CHPPh2)] have also been made. Reactions of I with bromine and hydrogen halides are described.