The structures of ring-expanded NHC supported copper(i) triphenylstannyls and their phenyl transfer reactivity towards heterocumulenes

Abstract

Three ring-expanded N-heterocyclic carbene-supported copper(I) triphenylstannyls have been synthesised by the reaction of (RE-NHC)CuOtBu with triphenylstannane (RE-NHC = 6-Mes, 6-Dipp, 7-Dipp). The compounds were characterised by NMR spectroscopy and X-ray...

The structures and reactivity of NHC-supported copper(i) triphenylgermyls

“…These metrics are similar to those previously observed for (NHC)CuEPh 3 systems (E = Si, Sn); in particular, Kleeberg 4 reported a corresponding silicon system for IPr ( i.e. the lighter congener of 2 ), its tin analogue was reported by Sadighi 14 and the heavier congeners of 3 and 4 were described by us 16 (relevant bond lengths (Å) and angles (°): (IPr)CuSiPh 3 , C–Cu, 1.9333(1); C–Cu–Si, 170.53(4); (IPr)CuSnPh 3 , C–Cu, 1.914(2); C–Cu–Sn, 169.6(8); (6-Mes)CuSnPh 3 , C–Cu, 1.927(3); C–Cu–Sn, 172.87(10); (6-Dipp)CuSnPh 3 , C–Cu, 1.934(3); C–Cu–Sn, 171.27(9)). 4,14,16 Comparison of the Cu–Ge bond distances between 1–4 show only limited variations as a consequence of the identity of the NHC, whereas comparison of 2 to (IPr)CuSiPh 3 and (IPr)CuSnPh 3 (Cu–E bond length (Å): 2 , 2.3038(3), 2.3085(3); (IPr)CuSiPh 3 , 1.9333(1); (IPr)CuSnPh 3 , 2.469(5)) exhibit unsurprising trends in the Cu–E bond lengths.…”

“…the lighter congener of 2 ), its tin analogue was reported by Sadighi 14 and the heavier congeners of 3 and 4 were described by us 16 (relevant bond lengths (Å) and angles (°): (IPr)CuSiPh 3 , C–Cu, 1.9333(1); C–Cu–Si, 170.53(4); (IPr)CuSnPh 3 , C–Cu, 1.914(2); C–Cu–Sn, 169.6(8); (6-Mes)CuSnPh 3 , C–Cu, 1.927(3); C–Cu–Sn, 172.87(10); (6-Dipp)CuSnPh 3 , C–Cu, 1.934(3); C–Cu–Sn, 171.27(9)). 4,14,16 Comparison of the Cu–Ge bond distances between 1–4 show only limited variations as a consequence of the identity of the NHC, whereas comparison of 2 to (IPr)CuSiPh 3 and (IPr)CuSnPh 3 (Cu–E bond length (Å): 2 , 2.3038(3), 2.3085(3); (IPr)CuSiPh 3 , 1.9333(1); (IPr)CuSnPh 3 , 2.469(5)) exhibit unsurprising trends in the Cu–E bond lengths. A similar, predictable, lengthening of the Cu–E bond length when comparing 3 or 4 to their corresponding tin congeners (6-Dipp)CuSnPh 3 and (6-Mes)CuSnPh 3 is also observed (Cu–E bond length (Å): 3 , 2.3045(3); (6-Mes)CuSnPh 3 , 2.4567(4); 4 , 2.3456(12); (6-Dipp)CuSnPh 3 , 2.4742(4)).…”

“…Addition of carbon dioxide, or di-iso-propyl carbodiimide, to 2 , provided no evidence of reactivity and even with extended reaction times only starting materials were isolable. This behaviour contrasts sharply with (IPr)CuSnPh 3 which was shown to transfer a phenyl group to both of these reagent classes to generate (IPr)CuX 2 CPh (X = N( p -tol), O) 14,16 with concurrent formation of “Ph 2 Sn” and with the observation that NHC-copper( i ) silyls have been reported to deoxygenate CO 2 to generate CO. 3…”

“…Compounds 1-4 crystallise as monomers with C-Cu-Ge geometries that are close to linear (C-Cu-Ge angle (°): 1, 169.49(6); 2, 171.24 (5), 171.36(5); 3, 173.48(5); 4, 171.77( 16)), which slightly increase upon going from the 5-to 6-membered carbene ligands. A concomitant increasing trend in the C-Cu bond length is apparent (C-Cu distance (Å): 1, 1.9185(18); 2, 1.9126 (16), 1.9182(16); 3, 1.9340(15); 4, 1.949 (6)). These metrics are similar to those previously observed for (NHC)CuEPh 3 systems (E = Si, Sn); in particular, Kleeberg 4 reported a corresponding silicon system for IPr (i.e.…”

“…15 We recently reported a series of ringexpanded NHC (RE-NHC) copper(I) triphenylstannyls, whose reactions with heterocumulenes also resulted in phenyl transfer and allowed us to propose an alternative mechanism associated with nucleophilic chemistry at tin in these systems. 16 Unlike their tetrel congeners, copper(I) complexes of organogermyl anions are far less well-explored. The rst triphenylphosphine supported copper(I) germyl compounds of the form (Ph 3 P) n CuGePh 3 (n = 1, 3) were reported from the reaction of Ph 3 GeLi with (Ph 3 P)CuCl by Hooton.…”