Borohidreto complexos de cobre (I) contendo difosfinas: caracterização espectroscópica e comportamento térmico

Abstract

[Cu(eta²-BH4)(dppm)] (1) > [Cu(eta²-BH4)(dppb)] (4) > [Cu(eta²-BH4)(cis-dppet)] (3). According to thermal analysis and X-ray diffraction patterns all compounds decomposed giving Cu(BO2)2, CuO, CuO2 and Cu as final products.]]>

Binuclear Copper(I) Borohydride Complex Containing Bridging Bis(diphenylphosphino) Methane Ligands: Polymorphic Structures of [(µ2-dppm)2Cu2(η2-BH4)2] Dichloromethane Solvate

“…The 31 P{ 1 H} spectrum ( Figure S3) shows only one singlet at −14.6 ÷ −16.5 (s) ppm (depending on concentration), which means the phosphorus atoms are magnetically equivalent. The signal is deshielded compared to the free dppm ligand (δ P = −21.7); at the same time its position is significantly different from that reported for monometallic dppm compound [71] (−148 ppm relative to (MeO) 3 P as a reference which is 140 ppm relative to 85% H 3 PO 4 used in this work). In the 13 (Table 2) and a band at 358 cm −1 , which can be attributed to the vibrations of the four-membered CuHBH cycle (ν CuB ) [67,94].…”

“…The complex was synthesized through a slight modification of a previously described procedure [71]. Bis(diphenylphosphino)methane (dppm) (0.5 g, 1.32 mmol) were added to a solution of bis(triphenylphosphine) copper(I) tetrahydroborate (0.8 g, 1.32 mmol) in 50 ml toluene.…”

“…The title copper(I) tetrahydroborate was synthesized by the ligand exchange in a manner similar to that given in [71], where of the reaction product was described as (η 2 -dppm)Cu(η 2 -BH 4 ). In our hands the procedure described in the Experimental Section yielded, upon recrystallization from CH 2 Cl 2 , a bimetallic complex with two bridging dppm ligands [(µ 2 -dppm) 2 Cu 2 ][η 2 -BH 4 ] 2 , the possible formation of such compound was suggested earlier in [93].…”

“…Since our attempt to synthesize the monomeric compound (η 2 -dppm)Cu(η 2 -BH4) (Figure 5a), previously described in [71] has failed, we attempted to optimize this structure by different DFT methods. However, these attempts were unsuccessful; instead of the proposed structure (Figure 5a), they gave the (η 1 -dppm)Cu(η 2 -BH4) complex stabilized by copper interaction with a phenyl ring (Figure 5b).…”

“…In particular, we have shown that the formation of bifurcate DHB complexes involving both bridging and terminal hydride hydrogens of (Ph3P)2Cu(η 2 -BH4) (Scheme 2) is prerequisite for the subsequent proton transfer and dimerization to occur [67]. Continuing these studies, we attempted the synthesis of (η 2 -dppm)Cu(η 2 -BH4) following the published recipe [71]. However, in our hands, it gave, instead, a binuclear dimer bearing two bridging μ2-dppm ligands between the two {Cu(η 2 -BH4)} moieties.…”