Heterodinuclear Diphosphane-Bridged Iron–Platinum Diyne Complexes as Metalloligands for the Assembly of Polymetallic Systems (Fe, Pt, Co)

Abstract

Treatment of [(OC)3Fe(μ-C=O)(µ-dppm)Pt(PPh3)] (1a) (dppm=Ph2PCH2PPh2) with 1,7-octadiyne affords the isomeric dimetallacyclopentenones [(OC)2Fe(µ-dppm)(µ-C(=O)C{(CH2)4C≡CH}=CH)Pt(PPh3)] (2a) and [(OC)2Fe(µ-dppm)(µ-C(=O)C(H)=C{(CH2)4C≡CH})Pt(PPh3)] (2a′). In a similar manner, the reaction with 1,3-diethynylbenzene and 1,4-diethynylbenzene yields [(OC)2Fe(μ-C(=O)C{C6H4–C≡CH}=CH)(μ-dppm)Pt(PPh3)] (2b,c); using [(OC)3Fe(μ-C=O)(µ-dppa)Pt(PPh3)] (1b) (dppa=Ph2PNHPPh2) as starting material provides [(OC)2Fe(μ-C(=O)C{p-C6H4–C≡CH}=CH)(μ-dppa)Pt(PPh3)] (2d). The isomeric μ-vinylidene complexes [(OC)3Fe(µ-dppm){(µ-C=CH(C6H4C≡CH)})Pt(PPh3)] (3b,c) result from treatment of [(OC)3Fe{Si(OMe)3}(μ-dppm)Pt(H)(PPh3)] with the two aromatic diynes. Reaction of 2a with a further equivalent of 1a yields the structurally characterized tetranuclear species [(OC)2Fe(µ-dppm)(µ-C(=O)C{(CH2)2}=CH)Pt(PPh3)]2 (4a). A dissymmetric heterotetranuclear dimetallacyclopentenone 4b is produced by reacting 2b with [(OC)3Fe(μ-C=O)(µ-dppa)Pt(PPh3)] (1b). An unusual heterotetranuclear dimetallacyclopentenone-μ-vinylidene compound 4c results from reaction of 3c with 1 equivalent of 1a. The dimetallacyclopentenone-dicobaltatetrahedrane cluster [(OC)2Fe(µ-dppm)(µ-C(=O)C{(CH2)4(η2-HC2Co2(CO)6}=CH)Pt(PPh3)] (5a) is formed by addition of [Co2(CO)8] to 2a. Likewise, [(OC)2Fe(µ-dppm)(µ-C(=O)C{C6H4(η2-HC2Co2(CO)4(µ-dppm)}=CH)Pt(PPh3)] (5b) is produced by mixing [Co2(CO)6(µ2-dppm)] with 2b. When attempting to prepare a heterotetranuclear complex by reacting 2a with [Co2(CO)6{P(OPh)3}2], the targeted compound was not formed. Instead, the substitution product [(OC)2Fe(µ-dppm)(µ-C(=O)C{(CH2)4C≡CH}=CH)Pt{P(OPh)3}] (6a) was isolated. 2b reacts in an analogous manner yielding [(OC)2Fe(μ-C(=O)C{C6H4–C≡CH}=CH)(μ-dppm)Pt{P(OPh)3}] (6b).