Self-Assembly of Cationic Pd(II)/Pt(II) Metallomacrocycles Containing Tetrahedral C₂Co₂ Clusters from Rigid Cluster-Bridged Bipyridine (4-C₅H₄N)₂C₂Co₂(CO)₆ and Diphosphine- or Diarsine-Chelated Pd(II)/Pt(II) Complexes [M(dppb)(H₂O)₂][OTf]₂ (M = Pd, Pt), [Pd(dpab)(H₂O)(OTf)][OTf], and [Pt(dpab)(H₂O)₂][OTf]₂

Abstract

The preparation, characterization, and some properties of the C2Co2 cluster-bridged bipyridine ligand (4-C5H4N)2C2Co2(CO)6 (1), diphosphine-chelated Pd(II)/Pt(II) complexes [M(dppb)(H2O)2][OTf]2 (dppb = 1,4-bis(diphenylphosphino)butane, OTf = SO3CF3; 2, M = Pd; 3, M = Pt), and the unique cationic cluster-containing Pd(II)/Pt(II) macrocycles {[M(dppb)]-μ-[(4-C5H4N)2C2Co2(CO)6]}2[OTf]4 (4, M = Pd; 5, M = Pt) and {[M(dpab)]-μ-[(4-C5H4N)2C2Co2(CO)6]}2[OTf]4 (dpab = 1,4-bis(diphenylarsino)butane; 6, M = Pd; 7, M = Pt) are reported. While ligand 1 is prepared by reaction of bis(4-pyridyl)acetylene with Co2(CO)8 in 61% yield, complexes 2 and 3 are prepared by reaction of M(dppb)Cl2 with silver triflate followed by hydrolysis of the intermediates M(dppb)(OTf)2 in 96% and 94% yields, respectively. Particularly interesting is that the self-assembly of ligand 1 with 2 and 3 results in formation of the C2Co2 cluster-containing macrocycles 4 and 5 in 62% and 65% yields, whereas 6 and 7 can be produced by self-assembly of 1 with diarsine-chelated complexes [Pd(dpab)(H2O)(OTf)][OTf] and [Pt(dpab)(H2O)2][OTf]2 in 79% and 68% yields, respectively. 1−7 have been fully characterized by elemental analysis, spectroscopy, and particularly for 2−7 X-ray crystallography, and for 1, 4, and 7 by cyclic voltammetric techniques.

Synthesis, characterization, and crystal structure of cis‐[Pt(Me)2{PPh2(OMe)}2] and the conversion into cis‐[Pt(OH2)2{PPh2(OMe)}2][OTf]2

“…Therefore, compound 2 is the first example of diaqua platinum complex with phosphinite ligands and also with two monodentate P ligands. The Pt‐O bond distances (2.149(7) and 2.131(8) Å) in 2 are similar to those reported before 7,11,12. The cationic part, [Pt(OH 2 ) 2 {PPh 2 (OMe)} 2 ] 2+ , has interaction with two uncoordinated OTf − anions through intermolecular hydrogen bonds between the hydrogen atom of coordinated water and the oxygen atom of uncoordinated OTf − anions (Fig.…”

“…In the 1 H NMR spectrum of 1 , an apparent triplet at δ 1.20 was observed with 6.0 Hz splitting, being reasonably assigned to the methyl groups on the Pt center. The observed coupling constant, 3 J (H–Pt) = 65.9 Hz, is in the range of those for cis‐ dimethylplatinum complexes having two tert ‐phosphorus ligands or a bidentate‐phosphine ligand (66–76 Hz) 7,8. The 31 P{ 1 H} NMR spectrum of 1 showed a signal at δ 116.71 flanked by 195 Pt satellites ( 1 J (P–Pt) = 2204 Hz).…”

“…Figure 2 shows a molecular representation of the dicationic complex 2 , in which the platinum atom is coordinated to the phosphorus atoms of the two PPh 2 (OMe) ligands in cis positions and the two OH 2 ligands, acquiring a square‐planer configuration. Only three crystal structures have been reported to date for a diaqua platinum complex having the phosphine ligand; cis‐ [Pt(OH 2 ) 2 (P–P)][OTf] 2 (P–P = diphenylphosphinobutane 7, diphenylphosphinoferrocene 11, and diphenylphosphinoethane 12). All of these complexes have a bidentate phosphine ligand.…”

1,6-Bis(diphenylarsino)hexane

“…For general background to and applications of diphenylarsino derivatives, see: Hill et al (1983); Song et al (2005). For the preparation of the title compound, see: Aguiar & Archibald (1967); Burfield et al (1977Burfield et al ( , 1978; Tzschach & Lange (1962).…”

“…A search of the November 2008 release of the Cambridge Structural Database (Allen, 2002) revealed no structures of complexes containing the above ligand. Among bis(diphenylarsino)alkanes, only the structure of 1,2-bis(diphenylarsino)ethane (Hill et al, 2001) and complexes of the ligand 1,3-bis(diphenylarsino)propane (Song et al, 2005) are known.…”