Unexpected bonding similarities between the bridging metalloligands [MoCp(CO)3]- and [PtI(CO)2(PPh3)]- acting as 4-electron donors in metal clusters. Crystal structures of [Pt2Mo(μ-CO)3(μ-PPh2)Cp(PPh3)2] and [Pt3(μ-CO)2(μ-PPh2)I(PPh3)3]

Reactions of the diplatinum complex [Pt-2(mu -H)(mu -PPh2)I-2(PPh3)(2)] with the carbonylmetalates [MCp(CO)(3)](-) (M = Mo, W) or [Co(CO)(4)](-) afforded the new 44e clusters [Pt2M(mu -CO)(3)(mu -PPh2)Cp(PPh3)(2)] (M = Mo, 2; M = W, 3) and [Pt-3(mu -CO)(2)(mu -PPh2)I(PPh3)(3)] 5, respectively, whose structures can be analysed as formed by a 26e [Pt-2(mu -PPh2)(PPh3)(2)](+) cation and a bridging, 4e donor anion, [MCp(CO)(3)](-) in 2 and 3, or the new 18e fragment [PtI(CO)(2)(PPh3)](-) in 5.