Ligand Exchange or Reduction at Multiply Bonded Dimetal Units of Molybdenum and Rhenium by 2,6-Bis(diphenylphosphino)pyridine

Abstract

Reaction of 2,6-bis(diphenylphosphino)pyridine (bdppp or (Ph(2)P)(2)Py)) with K(4)Mo(2)Cl(8) in refluxing methanol gives Mo(2)Cl(4)(bdppp)(2) (1) with retention of the quadruple Mo-Mo bond. However, the quadruply bonded octachlorodirhenate(III) anion, Re(2)Cl(8)(2)(-), reacts with bdppp under similar conditions to afford Re(2)Cl(4)(bdppp)(2) (2), which has a triply bonded dirhenium(II) core, Re(2)(4+). An intermediate species, [Bu(n)(4)N][Re(2)Cl(7)(bdppp)] (3), containing an Re(2)(6+) core and only one bridging bdppp ligand has also been isolated. The crystal structures of complexes 1-3 have been investigated by X-ray crystallography. In all cases the potentially tridentate bdppp acts as a bidentate ligand using one N and one of the P atoms, leaving the second phosphorus atom noncoordinated. The crystallographic parameters for these structures are as follows: Mo(2)Cl(4)(bdppp)(2).2CH(2)Cl(2) (1.2CH(2)Cl(2)), monoclinic space group P2(1)/c with a = 15.475(2) Å, b = 11.5958(7) Å, c = 16.7637 (6) Å, beta = 98.178(5) degrees, Z = 2; Re(2)Cl(4)(bdppp)(2) (2), monoclinic space group P2(1)/n with a = 16.173(2) Å, b = 11.285(1) Å, c = 28.771 (4) Å, beta = 96.17(1) degrees, Z = 4; [Bu(n)(4)N][Re(2)Cl(7)(bdppp)].CH(2)Cl(2) (3.CH(2)Cl(2)), triclinic space group P&onemacr; with a = 16.054(2) Å, b = 18.562(3) Å, c = 20.205 (6) Å, alpha = 89.71(2) degrees, beta = 73.21(1) degrees, gamma = 73.47(2) degrees, Z = 4.

Late transition metal complexes of a new P–N ligand Ph2PCH2N(H)C5H3(Cl-5)N: synthesis and structural studies

“…2 Crystal structure of compound 2 showing the hydrogen bonded dimer pair. 1)ÈN (28) 2.153(5) Pd( 1)ÈC (21) 2.009( 6) N( 28)ÈPd( 1)ÈC( 21) 83.3(2) Cl( 1)ÈPd( 1)ÈN (28) 91.2(1) Cl( 1)ÈPd( 1)ÈP (1) 92.15(6) P( 1)ÈPd( 1)ÈC (21) 94.1(2) Cl( 1)ÈPd( 1)ÈC (21) 171.4(2) P( 1)ÈPd( 1)ÈN( 28 Cl( 2)ÈPt( 1)ÈP(1) 87.23( 5) Cl( 1)ÈPt( 1)ÈCl (2) 87.69(5) Cl( 1)ÈPt( 1)ÈP (2) 88.92(5) P( 1)ÈPt( 1)ÈP (2) 96.72(4) Cl( 1)ÈPt( 1)ÈP (1) 169.90(4) Cl( 2)ÈPt( 1)ÈP (2) 174.75 (5) the tertiary phosphine ligands. In contrast complex 8 displays two singlets at d(P) 29.7 and 15.4 consistent with both cis and trans isomers35 present in solution (ca.…”

Tetrakis(μ-benzothiazole-2-thiolato)-1:2κ4N:S2;1:2κ4S2:N-dichloro-1κCl,2κCl-dirhenium(III)(Re—Re) dichloromethane solvate: a bridged complex with a long Re—Re quadruple bond

“…In the major component, [Re 2 (S 2 NC 7 H 4 ) 4 Cl 2 ], of the title compound, (I), each of the four benzothiazole-2-thiolate ligands bridges the dirhenium unit by binding through one S atom and the N atom, rather than through both S atoms. The preference of Re III for forming bonds to N rather than S has been documented previously by the discovery of N-bound thiocyanate ligands in the [Re 2 (NCS) 8 ] 2À ion (Cotton et al, 1967).…”

“…All torsion angles about the dirhenium units are less than 12 , but the ReÐRe bond distances range from 2.270 to 2.304 A Ê . This elongation of the quadruple bonds has been attributed to the presence of axial Cl À ligands (Cotton et al, 1998).…”

“…In each of these molecules, there is at least one bridging ligand. These bridging ligands are 2,6-bis(diphenylphosphino)pyridine (Cotton et al, 1998) and N,N H -diarylformamidinate, where aryl is p-tolyl (Cotton & Ren, 1992), and p-methoxyphenyl, 3,4-dichlorophenyl and 3,5-dichlorophenyl (Eglin et al, 1999). All torsion angles about the dirhenium units are less than 12 , but the ReÐRe bond distances range from 2.270 to 2.304 A Ê .…”

Activation of CX (=Cl, Br) bond in aryl halides toward the palladium-catalyzed Heck reaction using 2,6-bis(diphenylphosphino)pyridine

“…1. The coordination chemistry of (Ph 2 P) 2 py has been well studied [24][25][26][27][28], but relatively scarce attention has been given to its application as a supporting ligand in catalysis.…”