Interaction of organotin compounds with trans-carbonylchlorobis(triphenylphosphine)platinum(II) perchlorate
Abstract
The reactions of trans-[Pt(CO)Cl(PPh3)2][ClO4] with aryltrialkyl-, tetra-aryl-, and tetra-alkyl-tin compounds (usually in dichloromethane) have been studied, mainly by 31P-{1H} n.m.r. spectroscopy. Tetramethyltin gives trans-[Pt(CO)Me(PPh3)2][ClO4] quantitatively at room temperature. With SnRMe3 compounds (R = aryl) the main product is again trans-[Pt(CO)Me(PPh3)2][ClO4], but trans-[PtR(Cl)(PPh3)2] is also usually produced, and sometimes trans-[Pt(CO)R(PPh3)2][ClO4]. The styryl compound Sn(CHCHPh)Me3 likewise gives mainly trans-[Pt(CO)Me(PPh3)2][ClO4] together with trans-[Pt(CHCHPh)Cl(PPh3)2]. The neutral complexes such as trans-[PtR(Cl)(PPh3)2] may arise by loss of CO from trans-[Pt(CO)Cl(PPh3)2][ClO4] to give [Pt2Cl2(PPh3)4][ClO4]2 followed by reaction of the latter with the excess of SnRMe3. The reaction of trans-[Pt(CO)Cl(PPh3)2][ClO4] with Sn(CH2CHCH2)Me3 gives exclusively [Pt2Cl2(PPh3)4][ClO4]2 and this is also the main product from SnPh4, but substantial amounts of trans-[PtPh(Cl)(PPh3)2] and trans-[Pt(CO)Ph(PPh3)2][ClO4] are also formed in this case. Tetraethyltin gives initially trans-[Pt(CO)Et(PPh3)2][ClO4], but this subsequently decomposes to give finally an unidentified complex. This is also formed from SnREt3, SnRBun3, and SnPri4[and from SnMe4 and Sn(C6H4OMe-p)Me3 at higher temperatures], and is suggested to be a carbonyl-bridged platinum cluster complex. In reactions of SnMe4, SnPh4, Sn(C6H4OMe-p)Me3, and SnPhMe3, with trans-[Pt(CO)ClL2][ClO4]–cis-[PtCl2L2] mixtures (L = PEt3 or PMe2Ph), the cis-[PtCl2L2] species (which are normally inert to such organotin reagents) are brought into reaction, and this accounts for the substantial formation of trans-[PtMe(Cl)L2] from SnMe4. The complex trans-[Pt(CO)Cl(PPh3)2][ClO4] reacts with PbPhMe3 to give trans-[Pt(CO)Me(PPh3)2][ClO4], trans-[PtMe(Cl)(PPh3)2], and cis-[PtMe2(PPh3)2], together with trans-[PtPh(Cl)(PPh3)2], and the last complex is the sole product from PbPh4. The reaction with Hg(C6H4Me-p)2 gives the neutral aroyl complex trans-[Pt(COC6H4Me-p)Cl(PPh3)2] together with trans-[Pt(CO)(C6H4Me-p)(PPh3)2][ClO4] and trans-[Pt(C6H4Me-p)Cl(PPh3)2]. Sodium tetraphenylborate gives exclusively trans-[Pt(CO)Ph(PPh3)2][ClO4], and is the reagent of choice for this conversion. The GeRMe3 and SiRMe3 compounds examined did not react.