Neutral 8-(5-iodo-n-pentyl)-3-(eta (5)-pentamethylcyclopentadienyl)-arachno-3-rhoda-7,8-dithiaundecaborane, [Rh(C(5)H(19)B(8)IS(2))(C(10)H(15))], obtained from the [arachno-7,8-S(2)B(9)H(10)](-) anion by treatment with I(CH(2))(5)I followed by [Rh(C(5)Me(5))Cl(2)](2) and N,N,N',N' -tetramethyl-1,8-diaminonaphthalene, has the 11-vertex cluster geometry of [arachno-7,8-S(2)B(9)H(10)](-), but with an {Rh(C(5)Me(5))} unit in the 3-position instead of a {BH} unit, and with a -(CH(2))(5)I chain attached exo to an S atom.