Isolation of a Stable Precursor for [Pt0P-P] and Its Reductive Addition to Ru3(CO)9(μ3-S)2 Giving Square Heterometallic Clusters Supported by Two Face-Capping μ4-Sulfides [P-P = (C5H4PPh2)2M; M = Fe, Ru]

Abstract

Two labile but air-stable Pt(0) complexes Pt(η2-P-P)(η2-dba) [dba = dibenzylideneacetone; P-P = 1,1′-bis(diphenylphosphino)ferrocene (dppf) (3a) or 1,1′-bis(diphenylphosphino)-ruthenocene (dppr) (3b)] were prepared from Pt2(dba)3 (1) and the corresponding metallocenyl diphosphine. Reductive addition of 3 to Ru3(CO)9(μ3-S)2 (4) gave good yields of two novel square clusters PtRu3(CO)6(μ-CO)2(η 2-P-P)(μ4-S)2 [P-P = dppf (5a) or dppr (5b)]. A one-pot reaction mixture containing 1, 4, and the diphosphine (2) gave Ru3(CO)7(μ-P-P)(μ3-S)2 [P-P = dppf (6a) or dppr (6b)] along with 5a and 5b. All products have been characterized by IR, 1H, and 31P{1H} NMR. In addition, X-ray crystal analyses were also performed on complexes 3a, 5a, 5b, and 6a. 3a is a planar Pt(0)-olefin complex stabilized by chelating dppf and a trans,trans-d\)Si moiety coordinated via a C=C functionality. Compounds 5a and 5b are rare examples of almost regularly octahedral heterometallic square clusters with two μ4-8 ligands above and below the PtRu3 plane.