Thesis Summary
Organic Main Group Element Research Group
Zhang, Sihan

Multinuclear Coinage Metal Complexes of Bis(diphenylphosphinyl)functionalized Dipyrido-annulated N-heterocyclic Carbene(˦ˌ(ˋ˨ʺ˞˾ˮˌ˨ʶ˞˾)⪗俼⛹ʮ㘈ɵʧˋ˧˽˜䴭䎯N-˫˙̀ˈʷ˂˽˖˂ʾ˾ˬ̆ʊ⠙㜷宧ⵢ惐⭝戮Ṓ)
1. General Introduction (Chapter 1)
Phosphine-functionalized N-heterocyclic carbene (NHC)
supported multinuclear coinage metal complexes attract considerable
attention owing to their diverse structures, metal-metal interactions andinteresting photoluminescence properties. Generally, two types ofancillary ligands that most are based on the Arduengo type澳imidazole
scaffold are found in these complexes, namely the phosphinefunctionalized NHC ligands with and without spacers between
phosphine and carbene moieties (Figure 1, A and B). The type A whosecarbene and phosphine donors are in close proximity usually form
multinuclear complexes with intramolecular metal-metal interactions.
While oftentimes, the structural diversity is absent in these complexes
due to the rigid 2-D structure and limited rotation along the N-P bondof A (rotation around x axis only). The type B allowing the rotation ofphosphine arms in all directions form multinuclear complexes with diversified coordination geometries. However,intramolecular metal-metal interactions which have been proved to affect photoluminescence properties of resulting
complexes usually can not be found in these complexes, due to the long distance between carbene and phosphinedonors and the flexibility of the phosphine arms.
In this context, our group designed and achieved a diphosphine-functionalized NHC,bis(diphenylphosphinyl)-functionalized dipyrido-annulated NHC (dpaP2-NHC, Figure 1, C). This ligand features rigid
structure, whose carbene and phosphine donors
are in close proximity. More importantly, thecharacteristic of the phosphine arms rotating
freely around y axis enable access to different
coordination geometries.
2. Di- and tetranuclear Au(I) complexes ofbis(diphenylphosphinyl)-functionalized
dipyrido-annulated NHC (Chapter 2)澳
Starting from dpaP2-NHC and its
imidazolium salt precursor L(H)I, three
dinuclear and one tetranuclear Au(I) complexes(1-4) have been synthesized and structurally
characterized (Scheme 1). Specially, dpaP2NHC supported gold(I) complexes (2-4) feature
intramolecular aurophilic interactions, in which2 and 4 were found to undergo
dynamic behavior in solution
judging
fromNMR
spectroscopy,suggesting
weak coordination. All thecomplexes are fluorescent atroom temperature in solution(Figure 2) and interestingly,phosphorescent at 77 K withlong lifetimes ranging from 85.1 to 772.0 μs (Figure 3). Complexes 1-4 showed almost same emissions centered ataround 500 nm, which are comparable to that of the carbene ligand dpa P2-NHC, indicating that the electronic transitionof these gold(I) complexes are mostly attributed to ligand-centered (LC) transitions.澳
3. Multinuclear Cu and Ag Complexes of Bis(diphenylphosphinyl)-functionalized Dipyrido-annulated Nheterocyclic Carbene (Chapter 3)
A series of homonuclear
complexes of dpaP2-NHC havebeen achieved (Scheme 2),
including two dinuclear silver andcopper complexes (Ag2L2 andCu2L2), two tetranuclear copper
complexes [Cu4L2(NCMe)2 andCu4LBr4] and a pentanuclear
copper complex (Cu5L2Br3).
Judging
from
their
NMR
spectroscopy, all the complexes
show fluxional behavior insolution, in which, particularly,
Ag2L2 underwent a dissociative
process according to thecalculated
Eryingplot.
Interestingly, Cu2L2 contains
two different carbenes, namely aμ-bridging carbene and aterminal carbene. All thecomplexes were found to befluorescent at room temperature
in solution (Figure 4), in which
three homonuclear copper complexes [Cu4L2(NCMe)2, Cu4LBr4 and Cu5L2Br3] can provide phosphorescence at 77
K (Figure 5). Same with aforementioned gold complexes, the electronic transitions of these complexes are also mostly
attributed to LC transitions, due to their similar emissions with that of dpaP2-NHC.澳
Publications
S. Zhang, R. Shang, M. Nakamoto, Y. Yamamoto, Y. Adachi and J. Ohshita, Inorg. Chem., 2019, 58(9), 6328–6335.
S. Zhang, R. Shang, M. Nakamoto, Y. Yamamoto, Y. Adachi and J. Ohshita, Dalton Trans., 2019, accepted.