Borido clusters

Novel boron-gold bonds containing complexes are realized in two borido clusters. Addition of [HFe4(CO)i2BH] ppn to xs (PPhjIAuCl in CH2CI2 forms the green-brown, air-sensitive Fe4(CO) 2(AuPPh,)2BH ... 

A structural variation shows the borido cluster d HFe4(CO),2(Et3PAu)2B, where the B atom is within bonding contact of all six metal atoms and the two Au atoms symmetrically bridge the wingtips of the butterfly-shaped complex ... 

Three further borido clusters have been documented Co6(CO)lgB, HRu6(CO)17B, and [Ru6(CO),7B]. Co6(CO),8B is reported to be a product in the reaction of Co2(CO)g with BBr3 at 60°C or after exposing Co2(CO)g to 8-10 atm of B2H6. No structural data are available, and characterization is by elemental analysis and infrared spectroscopy only (22). The only closo homonuclear metalloboride cluster to be structurally characterized to date is HRu6(CO),7B (27). It is produced thermally at 75°C when... 

Fourteen years passed between the report of the boride from Schmid and cow-orkers, and that of the next fully encapsulated boron atom in a discrete molecular environment Shore s group described [HRu6(CO)nB], the octahedral structure (Fig. 1) being confirmed by the results of an X-ray diffraction studyj The metal-bound H atom is readily removed, and Shore also reported the isolation of [(Ph3P)2N][Ru6(CO)nB].f Independently, we reported the synthesis and spectroscopic characterization of the salt [Me3NH][Ru6(CO)i7B]. These studies opened the door to the development of the chemistry of interstitial borido clusters. 

The redox propensity of the two isostructural borido dusters Fe4.(CO)12 Au(PPh3) 2BH and Fe4(CO)12 Au(AsPh3) 2BH has been studied [154]. Fig. 81, which refers to the latter, typifies the ability of these clusters to add electrons. They undergo, in Dichloromethane solution, a one-electron reduction, which generates the corresponding, short-lived, monoanion [Fe4(CO)12 Au(XPh3) 2BH] (X = As, P). The relevant redox potentials are reported in Table 23 together with the monoanion lifetimes. 

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