Palladium(II) and Platinum(II) Complexes of a Tetraphosphamacrocycle. X-ray Crystal Structures of Phosphorus Analogs of a (Tetramethylcyclam)metal Complex¹

Abstract

Palladium(II) and platinum(II) complexes with 1,4,8,11-tetramethyl-1,4,8,11-tetraphosphacyclotetradecane were prepared by a template reaction in which [M(MeHPCH2CH2PHMe)2]Cl2 (M = Pd, Pt) reacts with 1,3-dibromopropane in the presence of K2HPO4 as a base. The bromide salts of the Pd2+(6a) and Pt2+(6b) complexes were isolated as crystals in a low yield. Their molecular structures were determined by X-ray crystallography. Both compounds have a square-planar geometry in which the configurations of the four asymmetric phosphorus atoms are of the trans III (RRSS) type. The M−P bond distances for 6a and 6b are 2.268(1) and 2.277(2) Å, respectively, which are slightly smaller than those of the complexes with noncyclic phosphines. Crystallographic data for 6a: monoclinic, space group C2/m, a = 8.4856(7) Å, b = 17.273(1) Å, c = 9.5712(7) Å, β = 101.117(7)°, V = 1376.5(2) Å3, Z = 2, and R = 0.042. Crystallographic data for 6b: triclinic, space group P1̄, a = 9.538(3) Å, b = 9.781(2) Å, c = 8.719(1) Å, α = 115.34(2)°, β = 92.92(2)°, γ = 61.33(2)°, V = 632.6(3) Å3, Z = 1, and R = 0.041.

18-Atom-Ringed Macrocyclic Tetra-imidazoliums for Preparation of Monomeric Tetra-carbene Complexes

“…To our knowledge, few neutral tetra-dentate strong σ-donor ligands have been synthesized. In fact, few macrocyclic tetra-dentate phosphines have been prepared and isolated, due to their difficult syntheses, instability, and sensitivity to O 2 . Lately, N-heterocyclic carbenes (NHCs) have become a more attractive alternative to phosphines for many catalytic applications .…”

Synthesis of Macrocyclic Polyphosphine Oxides and Phosphines by Template Cyclisation and Demetallation

“…The stepwise cyclisation process and the exchange of the counter ions Br -, HCO 3 and triflate in the first coordination sphere of Cu(I) were easily followed by electrospray mass spectrometry. No reaction 13 or very low yields 10 have been reported in similar approaches when reacting an alkyl dihalide with the methyl[2-(methylphosphino)ethyl]phosphinePd(II) or -Ni(II) complexes rather than the bis-phenyl derivative 2 used here.…”

“…Metal complex 2 is reasonably stable in air during several months as shown by NMR and by electrospray mass spectrometry and it can be handled with no special precaution. Metal derivatives such as 2 can react with dihalides 10 or with diketones or dialdehydes to yield polyphosphines or their polyhydroxylated analogues. 11,12 We selected the former approach and reacted 2 with 1,2-bis(chloromethyl)benzene and 1,3-dibromopropane.…”

Structure and Properties of the Macrocyclic Tridentate Ferrocenylphosphine Ligand (−PhPC5H4FeC5H4−)3

“…A vast number of aza and oxa macrocyclic ligands have been investigated so far. , In contrast, studies on phospha macrocycles, especially on those with a medium ring size, are relatively limited in number. , Since the early works by Horner et al and Kyba et al, who synthesized [11]ane P 3 macrocycles 30 years ago, , several groups have reported the synthesis of medium-ring-size phospha macrocycles. – In particular, Edwards et al recently established a metal-template hydrophosphination method, in which a ring structure was constructed on a metal center by a self-coupling reaction among primary or secondary alkenylphosphines . By use of the ingenious template method above, a dozen P 3 macrocycles are known to date, but those having a functional group on their chelate rings have not been reported so far.…”