Addition of palladium and platinum tri-tert-butylphosphine groups to Re-Sn and Re-Ge bonds

The reaction of Re-2(CO)(8)[mu-eta(2)-C(H)=C(H)Bu-n](mu-H) with Ph3SnH at 68 degrees C yielded the new compound Re-2(CO)(8)(-)(mu-SnPh2)(2) (10) which contains two SnPh2 ligands bridging two Re(CO)4 groups, joined by an unusually long Re-Re bond. Fenske-Hall molecular orbital calculations indicate that the bonding in the Re2Sn2 cluster is dominated by strong Re-Sn interactions and that the Re-Re interactions are weak. The Sn-119 Mossbauer spectrum of 10 exhibits a doublet with an isomer shift (IS) of 1.674(12) mm s(-1) and a quadrupole splitting (OS) of 2.080(12) mm s(-1) at 90 K,characteristic of Sn(IV) in a SnA(2)B(2) environment. The IS is temperature dependent, -1.99(14) x 10(-4) mm s(-1) K-1; the QS is temperature independent. The temperature-dependent properties are consistent with the known Gol'danskii-Kariagin effect, The germanium compound Re-2(CO)(8)(mu-GePh2)(2) (11) was obtained from the reaction of Re-2(CO)(8)[mu,eta(2)-C(H)=C(H)Bu-n](mu-H) with Ph3GeH. Compound 11 has a structure similar to that of 10. The reaction of 10 with Pd(PBu3t)(2) at 25 degrees C yielded the bis-Pd(PBu3t) adduct, Re-2(CO)(8)(mu-SnPh2)(2)[Pd(PBu3t)](2) (12); it has two Pd(PBu3t) groups bridging two of the four Re-Sn bonds in 10. Fenske-Hall molecular orbital calculations show that the Pd(PBut3) groups form three-center two-electron bonds with the neighboring rhenium and tin atoms. The mono- and bis-Pt(PBu3t) adducts, Re-2(CO)(8)(mu-SnPh2)(2)[Pt(PBu3t)] (13) and Re-2(CO)(8)(mu-SnPh2)(2)[Pt(PBu3t)](2) (14), were formed when 10 was treated with Pt(PBu3)(2). A mono adduct of 11, Re-2(CO)(8)(mu-GePh2)(2)[Pt(PBuB)] (15), was obtained similarly from the reaction of 11 with Pt(PBu3)(2).