Chelating versus bridging bonding modes of N-substituted bis(diphenylphosphanyl)amine ligands in Pt complexes and Co2Pt clusters

Abstract

N-substituted dppa ligands Ph2P-NR-PPh2 [R = -CH2CH2SCH2C6H5 (1), -CH2CH2S(CH2)5CH3 (2), -(CH2)9CH3 (3), -C6H5 (4)] were used for the synthesis of cis-[PtCl2{Ph2PN(R)PPh2}] complexes [R = -CH2CH2SCH2C6H5 (5), -CH2CH2S(CH2)5CH3 (6), -(CH2)9CH3 (7), -C6H5 (8)] and heterotrinuclear clusters of formula [PtCo2(CO)7{Ph2PN(R)PPh2}] [R = -CH2CH2SCH2C6H5 (9), -CH2CH2S(CH2)5CH3 (10), -(CH2)9CH3 (11), -C6H5 (12)]. The presence of relatively bulky substituents on N resulted in a higher chelating power of the ligands. The thermodynamic study of the equilibrium between the chelate and the bridged forms of clusters 9-11 showed that the bridged form is favoured by enthalpic factors whereas entropic factors favour chelation. The structures of 5 and 9 were determined by single crystal X-ray diffraction.

Heteroatoms moving protons: Synthetic and mechanistic studies of bifunctional organometallic catalysis

“…Moreover, 12a is ineffective as an alkyne hydration catalyst, whereas 12b (which becomes 4b during hydration reactions) shows excellent activity [22,23,33]. Additionally, we note that increasing the size of "innocent" phosphine R groups promotes chelation [25,34], an organometallic manifestation of the Thorpe-Ingold or gem-dialkyl effect [35][36][37][38]. Our success in creating efficient and highly active catalysts for alkyne hydration and alkene isomerization ( Fig.…”

Polymerization Isomerism in Co-M (M = Cu, Ag, Au) Carbonyl Clusters: Synthesis, Structures and Computational Investigation

“…We may view 6 as being composed by an Au(III) center coordinated to two [Co 2 (CO) 7 ] 2− anions (Figure 8), and its structure is reminiscent of [Au{Fe 2 (CO) 8 }] −[49]. The structure of the free anion [Co 2 (CO) 7 ] 2− has not been reported in the literature, but several of its adducts with main group and transition metals have been structurally characterized[50][51][52]. In agreement with the +3 oxidation state, the Au center is perfectly square planar.In contrast, 7 may be viewed as composed of an Au(I) center coordinated to two [Co 3 (CO) 9 ] − anions, acting as triply bridging ligands (Figure9).…”

Synthesis, structures, and electrocatalytic properties of phosphine‐monodentate, −chelate, and ‐bridge diiron 2,2‐dimethylpropanedithiolate complexes related to [FeFe]‐hydrogenases

“…Me 3 NO·2H 2 O, P(C 6 H 4 R‐ p ) 3 (R = Me, Cl), (Ph 2 P) 2 CH 2 (dppm) and CF 3 CO 2 H (TFA) were commercially available and used as received. Compounds Fe 2 ( μ ‐Me 2 pdt)(CO) 6 ( A ) and aminodiphosphine (Ph 2 P) 2 NR (R = Ph, Bu n ) were prepared according to the literature procedures . Preparative TLC was performed on glass plates (25 cm x 20 cm x 0.25 cm) coated with silica gel G (10–40 mm).…”