Maxwell A. Cairns

Catalytic cyclodimerisation of butadiene by CoCl(PPh3)3

Abstract CoCl(PPh3)3 acts as a catalyst for the cyclic dimerisation of butadiene to 1,5-cyclooctadiene and 4-vinyl-1-cyclohexene at 60° CoCl(PPh3)3 reacts with trifluorophosphine at room temperature to form the hydride complex CoH-(PF3)3 (PPh3).

Synthesis and catalytic activity of some π-allylic bis(trifluorophosphine)(triphenylphosphine)cobalt(I) complexes

Abstract The syntheses of Co(π-all)(PF3)2(PPh3) complexes (π-all = π-allyl, anti-1-Me-π-allyl, syn-1-Me-π-allyl, 1,1-dimethyl-π-allyl, anti-1,2-diMe-π-allyl, syn,syn-1,3-diMe-π-allyl, 2Et-π-allyl, π-cyclooctenyl, h3-π-cycloheptadienyl) are described. 1H and 19F NMR data are presented and discussed in relation to the structures of the complexes. The compound Co(π-C5H9)(PF3)(PPh3)2 is also reported. Several of the π-allylic complexes are found to be active catalysts for the isomerisation of 1-octene to 2-octene under a hydrogen atmosphere.

Synthesis, reactions and catalytic activity of some mixed trifluorophosphine(triphenylphosphine)hydrido complexes of cobalt(I)

Abstract The complexes CoH(PF 3 ) 4− n (PPh 3 ) n ( n = 1–3) have been prepared by low from the reaction between CoH(PF 3 )(PPh 3 ) 3 and butadiene. The hydrido complexes are active catalysts for the isomerisation of 1-octene to 2-octene under hydrogen or nitrogen.

New type of π-allyl isomerisation: conversion of 1,1-into 1,2-dimethylallyl complexes of cobalt and rhodium

The first examples of isomerisation of 1,1-dimethyl-π-allyl metal complexes to the corresponding 1,2-dimethyl-π-allyl compounds are described.

π-Allylic complexes of cobalt(I) containing trifluorophosphine

Abstract Several π-allylic complexes of cobalt(I) containing trifluorophosphine have been synthesised; they are much less reactive than their rhodium analogues and do not undergo phosphine exchange at room temperature.

Fluoro-complexes of platinum metals

Metathetical reactions of AgF with chloro-complexes give the fluoro-complexes [PtF(PEt3)3][BF4], trans-[PtF(PEt3)2(PPh3)][ClO4], trans-[PtF(PEt3)2{P(OPh)3}][ClO4], [PtF(PPh3)3][BF4], [PtF(PMe2Ph)3][BF4], [PdF(PEt3)3][BF4], trans-[RhF(CO)(PPh3)2], and trans-[IrF(CO)(PPh3)2]. These products are fully characterised by 19F and 31P n.m.r. spectroscopy, and 31P n.m.r. parameters are also reported for the chloro-complexes [PtCl(PEt3)3][BF4], trans-[PtCl(PEt3)2(PPh3)][ClO4], trans-[PtCl(PEt3)2{P(OPh)3}][ClO4], and [PtCl(PPh3)3][BF4]. The results suggest that the Pt–F bonding orbital has only small contributions from the Pt 6s and F 2s orbitals. The trans influence of fluorine in these complexes is usually slightly greater than that of chlorine and the Pt–F bond is probably stronger than corresponding Pt–Cl bonds. Hydrolysis of the platinum fluorides yields hydroxo-bridged complexes, [Pt2(OH)2(PR3)4]2+, and reaction of these products with excess of tertiary phosphine gives platinum hydrides, [PtH(PR3)3]+. Reaction of [Pt(PPh3)4] with excess of anhydrous HF yields [PtF-(PPh3)3][HnFn+1](n ∼ 2–3).

(η-Allyl)tris(trifluorophosphine)cobalt(I) complexes

A series of complexes [CoL(PF3)3][I; L = 1–3-η-allyl, -(1-methylallyl), -(1,1-dimethylallyl), -(1,2-dimethylallyl), -(1,3-dimethylallyl), -cyclo-octenyl, and -cycloheptadienyl] has been prepared by low-pressure ligand-displacement reactions. 1H and 19F N.m.r. studies indicate the absence of intermolecular phosphine exchange. The reactions of these complexes with hydrogen chloride and dihydrogen are discussed. The 1–3-η-(1,1-dimethylallyl) complex undergoes a novel thermal isomerisation to the anti-1,2-complex. The complex [Co(η-C7H9)(PF3)2] contains a 1–5-η-cycloheptadienyl group.