Synthesis and Structure of Pd₄(μ-P^tBu₂)₂(μ-CS₂)(PPh₃)₂I₂, a Neutral Palladium(I) Derivative with a Hexacoordinate Carbon and a CS₂ Molecule Bridging Four Palladium Centers

Abstract

The dinuclear CS2 complex [Pd2(μ-PtBu2)(μ,η2:η2-CS2)(PPh3)2]BF4, (2)BF4, reacts with Me4NI to yield the neutral tetranuclear Pd(I) derivative Pd4(μ-PtBu2)2(μ4-CS2)(PPh3)2I2 (4), which has been characterized by single-crystal X-ray diffraction. Its unusual molecular structure with a formally hexacoordinate carbon atom, as well as that of (2)+ with a planar tetracoordinate carbon can be explained on the basis of fragment MO considerations and EHMO model calculations. The reaction proceeds stepwise, with the relatively fast substitution of CS2 by the iodide ion giving the intermediate complex Pd2(μ-PtBu2)(μ-I)(PPh3)2 (3). The latter further reacts slowly with free CS2 to give complex 4 and free PPh3. Complex 3 was also prepared and isolated pure by reacting [Pd2(μ-PtBu2)(PPh3)3]BF4 with Me4NI.

Theoretical Overview of Pd(I) and Pt(I) Dimers with Bridging Phosphido Ligand(s)

“…General theoretical ideas have been reported that substantiate the above models. In particular, a qualitative MO analysis of the CS 2 adduct 1 4 has been presented . Also there are ab initio studies for the allyl derivative with one halide in place of the phosphido bridge .…”

Syntheses and crystal structures of neutral tetrairon complexes with the unique SCPPh2S ligand

“…16,17 The reported organometallic chemistry of CS 2 with transition metals includes examples such as the p-bound and bridged CS 2 ligand on a metal framework, insertion of CS 2 into an M-X bond (X = H, N, C, O) and coupling reactions. 14,16,18 Moreover, CS 2 has been observed to cleave, leading to the formation of thiocarbene, trithiocarbonate, or thiocarbonyl ligands. 19,20 Because of ever-growing interest in the activation of CS 2 from catalytic, synthetic and biological points of view, 13,[16][17][18][19][20][21][22] we have studied the reactions of [(m-RS)Fe 2 (CO) 6 (m-SCS À )] with Fe 3 (CO) 12 and Ph 2 PCl.…”

“…14,16,18 Moreover, CS 2 has been observed to cleave, leading to the formation of thiocarbene, trithiocarbonate, or thiocarbonyl ligands. 19,20 Because of ever-growing interest in the activation of CS 2 from catalytic, synthetic and biological points of view, 13,[16][17][18][19][20][21][22] we have studied the reactions of [(m-RS)Fe 2 (CO) 6 (m-SCS À )] with Fe 3 (CO) 12 and Ph 2 PCl. 23 In this communication we describe the unexpected results.…”

Bis(phospha-adamantyl)alkanes: a new class of very bulky diphosphines

“…(1) can be generalised to other diphosphines and other acetylacetones [eqn. (2)]. Hence the ligands 3-5a,b have been made in high yield as mixtures of diastereoisomers using the appropriate H 2 P(CH 2 ) n PH 2 and 1,3-diketone.…”