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

Treatment of [(OC)(3)Fe(mu-C=O)(mu-dppm)Pt(PPh3)] (1a) (dppm=Ph2PCH2PPh2) with 1,7-octadiyne affords the isomeric dimetallacyclopentenones [(OC)(2)Fe(mu-dppm)(mu-C(=O)C{(CH2)(4)C equivalent to CH}=CH)Pt(PPh3)] (2a) and [(OC)(2)Fe(mu-dppm)(mu-C(=O)C(H)=C{(CH2)(4)C equivalent to CH})Pt(PPh3)] (2a `). In a similar manner, the reaction with 1,3-diethynylbenzene and 1,4-diethynylbenzene yields [(OC)(2)Fe(mu-C(=O)C{C6H4-C equivalent to CH}=CH)(mu-dppm)Pt(PPh3)] (2b,c); using [(OC)(3)Fe(mu-C=O)(mu-dppa)Pt(PPh3)] (1b) (dppa=Ph2PNHPPh2) as starting material provides [(OC)(2)Fe(mu-C(=O)C{p-C6H4-C equivalent to CH}=CH)(mu-dppa)Pt(PPh3)] (2d). The isomeric mu-vinylidene complexes [(OC)(3)Fe(mu-dppm){(mu-C=CH(C6H4C equivalent to CH)})Pt(PPh3)] (3b,c) result from treatment of [(OC)(3)Fe{Si(OMe)(3)}(mu-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)(2)Fe(mu-dppm)(mu-C(=O)C{(CH2)(2)}=CH)Pt(PPh3)](2) (4a). A dissymmetric heterotetranuclear dimetallacyclopentenone 4b is produced by reacting 2b with [(OC)(3)Fe(mu-C=O)(mu-dppa)Pt(PPh3)] (1b). An unusual heterotetranuclear dimetallacyclopentenone-mu-vinylidene compound 4c results from reaction of 3c with 1 equivalent of 1a. The dimetallacyclopentenone-dicobaltatetrahedrane cluster [(OC)(2)Fe(mu-dppm)(mu-C(=O)C{(CH2)(4)(eta(2)-HC2Co2(CO)(6)}=CH)Pt(P Ph3)] (5a) is formed by addition of [Co-2(CO)(8)] to 2a. Likewise, [(OC)(2)Fe(mu-dppm)(mu-C(=O)C{C6H4(eta(2)-HC2Co2(CO)(4)(mu-dppm)}=CH )Pt(PPh3)] (5b) is produced by mixing [Co-2(CO)(6)(mu(2)-dppm)] with 2b. When attempting to prepare a heterotetranuclear complex by reacting 2a with [Co-2(CO)(6){P(OPh)(3)}(2)], the targeted compound was not formed. Instead, the substitution product [(OC)(2)Fe(mu-dppm)(mu-C(=O)C{(CH2)(4)C equivalent to CH}=CH)Pt{P(OPh)(3)}] (6a) was isolated. 2b reacts in an analogous manner yielding [(OC)(2)Fe(mu-C(=O)C{C6H4-C equivalent to CH}=CH)(mu-dppm)Pt{P(OPh)(3)}] (6b).