The photolysis of platinacycloalkanes in solution

The photolysis of [I₂$\text{PtCH}{}_2\text{CH}{}_2\text{CH}{}_2\text{C}$H₂ (PMe₂ Ph)₂] gives ethylene and but-1-ene as volatile products, the latter probably being formed via a five-coordinate platinum intermediate. However, the formation of propene from the photolysis of [Cl₂$\text{PtCH}{}_2\text{CH}{}_2\text{C}$H₂ (1,10-phenanthroline) appears to involve a direct transfer of a hydrogen atom between neighbouring CH₂ groups in the ring. Other gaseous products, e.g. cyclopropane, ethylene, may be formed via a platinum ion radical.     

Unusual route to and rearrangement of four-membered ring complexes C5H5Fe (CO) [ (C6H5)2PN(R)CH (C6H5) ]

The amine substituted phosphines (C₆H₅)₂PN(H)CH₂CH₃ and (C₆H₅)₂PN(H)CH₂C₆H₅ react with C₅H₅Fe(CO)₂CH(C₆H₅) (OCH₃) photolytically to give moderate yields of the four-membered chelate ring complexes C₅H₅$\text{Fe (CO) [(C}{}_6\text{H}{}_5\text{)}{}_2\text{PN (CH}{}_2\text{CH}{}_3\text{) C}$H (C₆H₅)] and C₅H₅$\text{Fe (CO) [(C}{}_6\text{H}{}_5\text{)}{}_2\text{PN (CH}{}_2\text{C}{}_6\text{H}{}_5\text{)C}$H(C₆H₅)], respectively. Photolysis of C₅H₅Fe(CO)₂CH(C₆H₅) (OCH₃) in the presence of (S)-(?)-diphenyl(1-phenylethylamino)phosphine leads to the isolation of C₅H₅Fe(CO)[(C₆H₅)2PNC(CH₃) (C₆H₅)]CH₂C₆H₅ which is proposed to arise from a formally 1,3-hydrogen shift rearrangement of an intermediate four-membered chelate ring complex.     

Transition metalcarbon bonds: XL. Palladium(II) complexes of [(dimethylamino)methyl]-ferrocene

C₅H₅FeC₅H₄CH₂NMe₂ reacts with sodium chloropalladate(II) in the presence of sodium acetate to give the internally metallated binuclear species [$\text{Pd}{}_2\text{X}{}_2\text{{C}{}_5\text{H}{}_5\text{FeC}{}_5\text{H}{}_3\text{CH}{}_2\text{N}$Me₂}₂] (X = Cl). The corresponding iodide was prepared as were mononuclear species [$\text{Pd(acac) {C}{}_5\text{H}{}_5\text{FeC}{}_5\text{H}{}_3\text{CH}{}_2\text{N}$Me₂}] and [$\text{Pd-{C}{}_5\text{H}{}_5\text{FeC}{}_5\text{H}{}_3\text{CH}{}_2\text{N}$Me₂}L] L = PMe₂Ph, AsMe₂Ph, P(OMe)₃ or PPh₃. ¹H NMR data are given.     

Cyclometallation reactions of N-(benzylidene)benzylamines with palladium compounds

The cyclometallation of p-RC₆H₄CHNCH₂C₆H₂, (R = H, Cl, NO₂) by PdX₂ (X = Cl, AcO) has been studied.In every case the cyclometallation occurs with formation of a five-membered ring containing the methine group. The structure of these compounds [$\text{PdX(}\text{p}\text{-RC}{}_6\text{H}{}_3\text{CHN}$CH₂C₆H₅)]₂, derived from ¹H NMR spectra, are different from those reported previously. Reaction of these compounds with PEt₃ gives the compounds [PdX(p-RC₆H₃CHNCH₂C₆H₅)(PEt₃)₂] but with an excess of PPh₃ only the complexes [$\text{PdX(}\text{p}\text{-RC}{}_6\text{H}{}_3\text{CHN}$CH₂C₆H₅)(PPh₃)] are formed.     

The preparation and catalytic hydroformylation activity of some halocarbonylrhodium(I) complexes containing phosphinoalkylorganosilicon ligands

The synthesis and properties of a series of trans-halocarbonylrhodium(I) complexes containing the phosphinoalkylorganosilicon ligands Me₃SiCH₂PPh₂, Me₃Si(CH₂)₃PPh₂, and PPh₂CH₂(Me)$\text{Si(OSiMe}{}_2\text{)}{}_3\text{O}$ have been investigated. The complexes could be prepared by an exchange reaction involving RhCl(CO)(PPh₃)₂ and the organosilicon ligands or in better yields by the reaction of Rh₂Cl₂(CO)₄ with the ligands. Iodorhodium derivatives were obtained as the exclusive products in the latter reaction if a small amount of LiI was present. The catalytic activity of RhCl(CO)(PPh₂CH₂SiMe₃)₂ was similar to that of RhCl(CO)(PPh₃)₂ in the hydroformylation of hex-1-ene at 100°C and 1000 psi pressure of H₂/CO. The catalytic properties of the iodo derivatives RhI(CO)L₂ [L = Me₃SiCH₂PPh₂, Me₃Si(CH₂)₃PPh₂, and PPh₂CH₂(Me)$\text{Si(OSiMe}{}_2\text{)}{}_3\text{O}$] varied considerably, with RhI(CO)(PPh₂CH₂SiMe₃)₂ producing an unexpectedly low linear/branched aldehyde product ratio.     

Isomerisation in the chemistry of platinacyclobutane complexes

The platinacyclobutane complexes PtCl₂L₂(C₃H₅Me)], L  pyridine, CD₃CN, or tetrahydrofuran, exist as mixtures of isomers containing P$\text{tCH}{}_2\text{CHMeC}$H₂ or P$\text{tCHMeCH}{}_2\text{CH}{}_2$ groups in rapid equilibrium. Decomposition occurs in some cases to give [PtCl₂L(CH₃CH₂CHCH₂)]. Stereospecific skeletal isomerisation also occurs in metallocyclobutanes containing the groups P$\text{tCHRCHRC}$H₂  P$\text{tCHRCH}{}_2\text{C}$HR, when R  aryl further decomposition gives ν-allylplatinum complexes.     

Reactions of hydridosilacyclobutanes with low-valent complexes of iron or platinum

Unstable transition metal compounds formed from hydridosilacyclobutanes are described: 1-methyl-1-silacyclobutane reacts with nonacarbonyldiiron to give the complexes [Fe(CO)₄(H){$\text{Si(Me)CH}{}_2\text{CH}{}_2\text{C}$H₂}] and [$\text{Fe{CH}{}_2\text{CH}{}_2\text{CH}{}_2\text{Si}$(H)Me}(CO)₄], and with bis(triphenylphosphine)(ethylene)platinum(0) to give [Pt(H)(PPh₃)₂{$\text{Si(Me)CH}{}_2\text{CH}{}_2\text{C}$H₂}].     

Synthesis of homoleptic tris(organo-chelate)iridium(III) complexes by spontaneous ortho-metallation of electronrich olefin-derived N,N′-diarylcarbene ligands and the X-ray structures of fac-[Ir{CN(C6H4Me-p) (CH2)2NC6H3Me-p}3] and mer-Ir{CN(C6H4Me-p)(CH2)2NC6H3Me-p}2 {CN(C6H4Me-p)(CH2)2NC6H4Me-p}Cl (a product of HCl cleavage)

Treatment of [{Ir(COD)(μ-Cl)}₂] with excess of the electron-rich olefin [$\text{CN(Ar)(CH}{}_2\text{)}{}_2\text{N}$Ar]₂ (abbreviated as (L^Ar)₂, Ar = C₆H₄Me-p or C₆H₄OMe-p) affords the ortho-metallated tricycle [$\text{Ir(L}{}^{\mathrm{A}}\text{r}$)₃], which for Ar = C₆H₄Me-p (Ia) with HCL yields [$\text{Ir(L}{}^{\mathrm{A}}\text{r}$)₂(L^Ar)]Cl (IV); X-ray data show that in IV there is an unexpectedly close Ir?C(o-aryl) contact (2;52(1) Å) involving the “free” L^Ar which compares with an IrC(o-aryl) distance of 2.09(3) Å in Ia or 2.07(3) Å in the ortho-metallated L^Ar ligand of complex IV.     

Darstellung ylidischer metallacyclopropankomplexe durch ringverkleinerung metallacyclischer vinylketonkomplexe. Molekülstruktur von C5H5W(CO)2[(PMe3)HC-CH(COMe)]

The addition of trimethylphosphane to five-membered metallacyclic vinylketone complexes of the type Ar$\text{M(CO)}{}_2\text{(HCCHCO}$R) (I) (Ar = η⁵-aromatic ring system: C₅H₅, C₅H₄Me, C₅Me₅; R = Me, Et, n-Bu; M = Mo, W) in pentane solution results in the formation of the ylidic metallacyclopropane complexes Ar$\text{M(CO)}{}_2\text{[(PMe}{}_3\text{)-HCC}$H(COR)] (II). In these 1:1 adducts the three-membered ring is stabilized by an electron-donating phosphonium and an electron-attracting acyl substituent. The negative charge in the ylidic complexes II is localized on the central metal providing it with Lewis base properties. An extraordinary high electron density can be observed on the metal of the derivative C₅H₅$\text{W(CO)(PMe}{}_3\text{)[(PMe}{}_3\text{)HCC}$H-(COMe)] (III) which is formed by a 1:2 addition of C₅H₅W(CO)(C₂H₂)-(COMe) and PMe₃. The metallacyclopropane complexes II and III are characterized by IR, ¹H NMR, ¹³C NMR, ³¹P NMR and mass spectroscopy. For C₅H₅$\text{W(CO)}{}_2\text{[(PMe}{}_3\text{)HCC}$H(COMe)], the results of an X-ray structure determination are presented.     

Reactions and properties of some trimethyleneplatinum(IV) complexes: VII. Kinetics and mechanism of displacement of cyclopropane by alkenes

The kinetics of the reaction of alkenes (e.g. cis-pent-2-ene, hex-1-ene, cyclopentene) with [$\text{PtX}{}_2\text{(CH}{}_2\text{CH}{}_2\text{C}$H₂)(THF)₂] (X = Cl or Br, THF = tetrahydrofuran) or with [$\text{PtCl}{}_2\text{(CHPhCH}{}_2\text{C}$H₂)(THF)₂] in THF solution have been studied. The reactions occur with displacement of cyclopropane or phenylcyclopropane to give [PtCl₂(olefin)(THF)], and follow essentially second order kinetics, first order in both platinum complex and olefin. The mechanism of reaction is discussed.     

Transition metalcarbon bonds: LV. Cyclometallation and other reactions of PBut2Bui and PPh2Bui with platinum(II) and palladium(II)

The new phosphine, PBu^t₂Buⁱ (L), was prepared from Bu^t₂PCl and LiBuⁱ. PPh₂Buⁱ (L′) was prepared from Ph₂PCl and LiBuⁱ. Treatment of [PtCl₂(NCBu^t)₂] with L′ gives [PtCl₂L′₂] which does not cyclometallate even on prolonged boiling in 2-methoxyethanol. In contrast, [PtCl₂(NCBu^t)₂] reacts with PBu^t₂Buⁱ in boiling 2-methoxyethanol to give the cyclometallated complex [$\text{Pt}{}_2\text{Cl}{}_2\text{(PBu}{}^{\mathrm{t}}{}_2\text{CH}{}_2\text{-CHMeCH}$₂)₂] (II, X = Cl). The corresponding bromide, iodide and acetylacetonate were prepared. With PPh₃ II (X = Cl) gives [$\text{PtCl(PBu}{}^{\mathrm{t}}{}_2\text{CH}{}_2\text{CHMeCH}$₂)(PPh₃)] which with NaBH₄ gives [$\text{PtH(PBu}{}^{\mathrm{t}}{}_2\text{CH}{}_2\text{CHMeC}$H₂)(PPh₃)]. Na₂PdCl₄ with L (2 mol equivalents) gave trans-[PdCl₂L₂], which was converted into trans-[Pd(NCS)₂-L₂] by metathesis with KSCN. Treatment of Na₂PdCl₄ with L (1 mol equivalent) gave [Pd₂Cl₄L₂], which on heating in 2-methoxyethanol gave [$\text{Pd}{}_2\text{Cl}{}_2\text{(PBu}{}^{\mathrm{t}}{}_2\text{CH}{}_2\text{-CHMeCH}$₂)₂], as a mixture of syn- and anti-isomers. The complexes trans-[PdCl₂-L′₂] and [Pd₂Cl₄L′₂] were also prepared. ¹H- and ³¹P NMR data are given.     

Reactions and properties of some trimethyleneplatinum(IV) complexes: V. The kinetics and mechanism of formation from arylcyclopropanes

The kinetics of the reaction of arylcyclopropanes (4-XC₆H₄C₃H₅, X = H, Me, EtO) with either [Pt₂Cl₂(μ-Cl)₂(C₂H₄)₂] or [{$\text{PtCl}{}_2\text{(CH}{}_2\text{CH}{}_2\text{C}$H₂)} in tetrahydrofuran to give in each case [{$\text{PtCl}{}_2\text{(CHArCH}{}_2\text{C}$H₂)}₄] and ethylene or cyclopropane, respectively, have been studied. The reactions are essentially first order in both arylcyclopropane and platinum complexes. The order of reactivity follows the series X = EtO > > Me > H, and [Pt₂Cl₂(μ-Cl)₂(C₂H₄)₂]> [{$\text{PtCl}{}_2\text{(CH}{}_2\text{CH}{}_2\text{C}$H₂)}4] and the rate is accelerated in polar solvents. Mechanisms in which the arylcyclopropane first coordinates to platinum and then undergoes ring opening reactions are proposed.     

1-[(π-Cyclopentadienyl)dicarbonyliron]-1-methylsilacyclobutane and related iron-substituted silacyclobutanes

Silicon-transition metallic silacyclobutanes CpFe(L₂)$\text{Si(Me)CH}{}_2\text{CH}{}_2\text{C}$H₂ [L = CO or Ph₂MeP; or L₂ = (CO)(Ph₂MeP)] have been prepared and their reactions (substitution at Si or Fe, Si—Fe cleavage, or ring-opening) studied.     

Some partially fluorinated cyclic and acyclic compounds of sulphur (II) and (IV) and partially fluorinated cyclic compounds of phosphorus (III) and (V)

Sulfinyl fluoride and N-(F-isoprophyl)iminosulfur difluoride form the compounds, O$\text{SN(CH}{}_3\text{)CH}{}_2\text{CH}{}_2\text{N}$(CH₃) and i-C₃F₇N$\text{SN(CH}{}_3\text{CH}{}_2\text{CH}{}_2\text{N}$(CH₃ with symdimethylethylenediamine (1). In contrast, CF₃C(O)NSF₂ and (R_f)₂SF₂ (R_f = CF₃, i-C₃F₇ form only acyclic compounds, CF₃C(O)N(CH₃)CH₂CH₂N(CH₃)C(O)CF₃ and R_fSN(CH₃)CH₂CH₂N(CH₃)SR_f with (1). With PF₃, PF₅ and OPF₃, cyclic compounds $\text{N(CH}{}_3\text{)CH}{}_2\text{CH}{}_2\text{N(CH}{}_3\text{)P}$F, $\text{N(CH}{}_3\text{)CH}{}_2\text{CH}{}_2\text{N(CH}{}_3\text{)P}$F₃, and $\text{N(CH}{}_3\text{)CH}{}_2\text{CH}{}_2\text{N(CH}{}_3\text{)P}$-(O)F result. When the latter two compounds are reacted further with LiNC(CF₃)₂, N(CH₃)CH₂CH₂N(CH₃)PF₂NC(CF₃)₂ and $\text{N(CH}{}_3\text{CH}{}_2\text{CH}{}_2\text{N(CH}{}_3\text{)P}$(O)NC(CF₃)₂) form.     

Cyclometallation reactions XII. On the effect of various leaving groups on internal metallation reactions with alkylmanganese complexes

The interaction of azobenzene and MnR(CO)₅ (R  Me, Et, CH₂Ph, CH₂-C₆Me₅, COCF₃, COCH₂C₆F₅, COCH₂OPh, Ph or C₆F₅) affords M$\text{n(C}{}_6\text{H}{}_4\text{NN}$Ph)-(CO)₄, together with a binuclear complex Mn₂(CO)₆(C₁₂H₁₀N₂) in some cases. The metallation reaction is shown to proceed most readily with Mn-(CH₂Ph)(CO)₅; with this reagent, the metallated complexes M$\text{n(C}{}_6\text{H}{}_4\text{CH}{}_2\text{P}$Me₂)-(CO)₃[PMe₂(CH₂Ph)] (two isomers) and M$\text{n(C}{}_6\text{H}{}_4\text{CH}{}_2\text{A}$sMe₂(CO)₄ have been obtained on treatment with EMe₂(CH₂Ph) (E  P and As, respectively).     

Synthesis of monohydridohexamethylbenzeneruthenium(II) complexes containing group V donor ligands. Isomerism arising from cyclometallation of a tertiary phosphine at aliphatic and aromatic carbon atoms

The η-hexamethylbenzenehydridoruthenium(II) complexes RuHCl(η-C₆Me₆)L (L = PPh₃ (11), AsPh₃ (12), P(C₆H₄-p-F)₃ (14), P(C₆H₄-p-Me)₃ (15), P(C₆H₄-p-OMe)₃ (16), P-t-BuPh₂ (17), P-i-PrPh₂ (18), P-i-Pr₃ (19), PCy₃ (20) and P-t-BuMe₂ (21)) have been made by heating [RuCl₂(η-C₆Me₆)]₂, the ligand and sodium carbonate in propan-2-ol. The triarylphosphine complexes 11, 14 and 15 react with methyllithium to give aryl ortho-metallated hydridoruthenium(II) complexes such as $\text{RuH(}\text{o}\text{-C}{}_6\text{H}{}_4\text{P}$Ph₂)(η-C₆Me₆) (22) and 19 similarly gives the isopropyl cyclometallated complex $\text{RuH(CH}{}_2\text{CHMeP}$-i-Pr₂(η-C₆Me₆) (29) as a mixture of diastereomers. Reaction of 17 with methyllithium gives initially the t-butyl cyclometallated complex $\text{RuH(CH}{}_2\text{CMe}{}_2\text{P}$Ph₂)(η-C₆Me₆) (25) which isomerizes by a first order process (k$\text{0}\text{?}$.2 h^?1 in C₆D₆ or THF-d₈ at 50°C) to the aryl ortho-metallated complex $\text{RuH(}\text{o}\text{-C}{}_6\text{H}{}_4\text{P}$-t-BuPh)(η-C₆Me₆) (26). The similarly generated isopropyl cyclometallated complex $\text{RuH(CH}{}_2\text{CHMeP}$Ph₂)(η-C₆Me₆) (27) has not been isolated in a pure state owing to rapid isomerization to $\text{RuH(}\text{o}\text{-C}{}_6\text{H}{}_4\text{P}$-i-PrPh)(η-C₆Me₆) (28); both 27 and 28 exist as a pair of diastereomers. The formation of the cyclometallated complexes and the isomerizations are thought to involve intermediate 16-electron ruthenium(O) complexes Ru(η-C₆Me₆)L.     

Oxidation of coordinated olefins: the reactions of Cl2 with trichloro(ehtylene)platinate(II)

The oxidation of [PtCl₃(C₂H₄)]- by Cl₂ in aqueous solution, to yield CH₂ClCH₂OH and [PtCl₄]^2-, has been shown to proceed through the following sequence of steps: [PtCl₃(C₂H₄)] Cl₂Cl [PtCl₅(CH₂CH₂Cl)]^2-$\text{H}{}_2\text{O}\text{(HCl)}$ [PtCl₅(CH₂CH₂OH)]^2- → [PtCl₄^2- + CH₂ClCH₂OHEach of the steps and intermediates in this mechanistic sequence has been identified and characterized.     

Metallorganische verbindungen des iridiums und rhodiums: XXVI. CH-metallierung und hydridbildung im system Ir2Cl2(C8H14)4/PR3(PR3 = P(CH2CMe3)3, t-BuP(CH2CMe3)2, t-Bu2PCH2CMe3; i-Pr3P

Treatment of Ir₂Cl₂(C₈H₁₄)₄ with the phosphines t-Bu_3?nP(CH₂CMe₃)_n (n = 3,2,1) in hot toluene followed by crystallization of the products from C₇H₈/ EtOH mixtures gave the cyclometallated hydrides (C₈H₁₄)₂Ir-μ-Cl₂$\text{IrH[CH}{}_2\text{CMe}{}_2\text{CH}{}_2\text{P}$(CH₂CMe₃)₂][P(CH₂ (I) [t-BuP(CH₂CMe₃)₂]₂H₂Ir-μ-Cl₂$\text{IrH[CH}{}_2\text{CMe}{}_2\text{CH}{}_2\text{P}$Bu^t(CH₂CMe₃)][t-BuP(CH₂CMe₃)₂] (II), and [(t-Bu₂$\text{PCH}{}_2\text{CMe}{}_2\text{CH}{}_2\text{)HI}$rCl]₂ (III). The dihydrides IrH₂Cl[t-BuP(CH₂CMe₃)₂]₂ (IIa) and IrH₂Cl(t-Bu₂PCH₂CMe₃)₂ (IIIa) were also isolated; these species were, however, more conveniently obtained by bubbling hydrogen through the solution of Ir₂Cl₂ (C₈H₁₄)₄ and the respective phosphine in toluene. i-Pr₃ reacted with the olefiniridium(I) precursor in C₇H₈/EtOH to yield the carbonyl complexes (i-Pr₃P)₂H₂Ir-μ-Cl₂Ir(CO)(PPrⁱ₃)₂ (IV) and IrCl(CO)(PPⁱ₃)₂ (IVa), no cyclometallated product being detected. The stereochemistries of the complexes were deduced from IR, ¹H, ³¹P, and ¹³C NMR data. The crystal structures of IIIa and IVa were also determined.     

Diazabutadienes as ligands: I. Compounds of aluminium: coordination of diazabutadienes to Al(CH3)3 and subsequent intramolecular insertion and rearrangement reactions leading to (CH3)2AIR—N—CH(CH3)—C(R')=N—R(R'= H,CH3) and (CH3)2AIR—N—CH2—C(CH3)=N—R

Reaction of R—N=CH—CH=N—R with [(CH₃)₃Al]₂ affords the coordination product (CH₃)₃AlRN=CH—CH=NR (A) for R = 2,6-(CH₃)₂C₆H₃ and 2,4,6(CH₃)₃C₆H₂. For R = 4 ClC₆H₄, 4-CH₃C₆H₄ and 4-CH₃OC₆H₄, insertion takes place, giving the complexes (CH₃)₂A$\text{lRN—CH(CH}{}_3\text{)—CH=N}$—R (B), in which Al is part of a five-membered chelate ring. Depending on the temperature both the addition and insertion products rearrange intramolecularly to the complexes (CH₃)₂-A$\text{lR—N—CH}{}_2\text{—C(CH}{}_3\text{)=N}$—R (C), in which Al is also part of a five-membered chelate ring. Reactions of the asymmetric (CH₃)₂HC—N=CH—C(CH₃)=N—CH-(CH₃)₂ with [Al(CH₃)₃]₂ also leads to an insertion product, (CH₃)₂A$\text{lRN-—CH(CH}{}_3\text{)—C(CH}{}_3\text{)=N}$—R (B') (R = (CH₃)₂CH), but there is no subsequent rearrangement in this case.A mechanism involving hydrogen migration is tentatively proposed to account for the observed isomerization, which increases in rate in the order:R = (CH₃)₃C>2,4,6-(CH₃)₃C₆H₂> 2,6-(CH₃)2C₆H₃ (A → C)andR = 4-CH₃OC₆H₄>4-CH₃C₆H₄>4-ClC₆H₄ (B → C)Hydrolysis of isomer C gives the unknown imino amines R—NH—CH₂-C(CH₃)=N—R in quantitative yield.     

The photodecomposition of platinacycloalkanes in solution.: I. 1,3-propanediylplatinum(IV) compounds

The gaseous products of the photolysis at 25°C of the platinacyclobutane compounds [X₂$\text{PtCH}{}_2\text{CH}{}_2\text{C}$H₂(N-N)] where X = Cl, Br and N-N = 1,10-phenanthroline, 2,2′-bipyridine, (CH₂NMe₂)₂, (C₅H₅N)₂ in several solvents, in the absence and presence of various additives, have been determined. With solvents of relatively low dielectric constant (e.g. CH₂Cl₂), over 85 mol % of the hydrocarbon products was propene, the formation of which appears to involve a direct transfer of a hydrogen atom between neighbouring groups in the ring. With solvents of relatively high dielectric constant (MeCN, Me₂SO) in the presence of species, e.g. I^?, SbPh₃, having a high trans effect, cyclopropane is the main volatile product. The effect of added halide ion and of the mixed solvents Me₂SO/PhMe and Me₂SO/PhSH indicates that ionisation of the platinacyclobutane and the formation of platinum substituted propyl ion-radicals precede the formation of cyclopropane (and the small amounts of ethylene produced).The photolysis of [X₂$\text{PtCH}{}_2\text{CH}{}_2\text{C}$H₂(MeCN)₂] in methyl cyanide solution in the presence of Et₃RNX′ (X′ = Cl, R = H; X′ = Br, R = Et) gives appreciable amounts of ethylene in the products (up to 25 mol %). It is suggested that the halide ions add to the platinum to give negatively charged platinacyclobutane species, the photodecomposition of which may give C₂H₄.