Effects of the Inverse Trans-Influence in a Berkelium(III) Phosphine Oxide Complex.

An example of a Bk phosphine oxide complex has been prepared to examine and quantify the effects of the inverse -influence (ITI) on a late actinide complex. This has been accomplished through a comparison of and Bk-ligand bonds in the meridional berkelium(III) complex, BkBr(OPCy) (OPCy = tricyclohexylphosphine oxide). A detailed bond metric analysis was completed that includes the shortest published distance for a Bk-O bond, attributed to the smaller coordination number of Bk of six in -BkBr(OPCy). ITI calculations of the Bk-O bond provide an ITI value (98.5(2)%) comparable to that of -AmBr(OPCy) (98.2(2)%) and indicate a small 5 orbital contribution to bonding. This effect is discussed in the context of the isomorphous lanthanide(III) series where the ITI is calculated to be higher for -BkBr(OPCy) than in most Ln analogues.