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X-Ray Structures

Note: this page is under construction - some of the images are low resolution, and will be replaced with higher resolution images over the next few months.

Alane-appended platinum complexes
FcPPB platinum complexes
Rh TXPB complexes
Rh-Fe heterobimetallic complexes of TXPB
Pd complexes of TXPB
Pt alkyl and aryl complexes of TXPB 
PS- and PSP-donor ligand complexes
Vinylborane complexes of Pt and Ni
Th complexes
U complexes
Y complexes
Alkali metal complexes
Mn complexes
Cu, Zn and Al complexes formed en route to copper metal deposition

An Alane-Appended Analogue of DPPF and its Platinum Complexes

We recently prepared an alane-appended analogue of dppf (dppf is a wide bite-angle bis-phosphine ligand used extensively in late transition metal catalysis). The ligand, FcPPAl:
FcPPAl ligand

The FcPPAl ligand binds tenaciously to platinum in a range of oxidation states, yielding complexes with square pyramidal, T-shaped, and distorted square planar geometry. The CO and dihydride complexes also feature unusual multiceter bonding between the alane, platinum, and either a carbonyl or a hydride ligand.

C2Ph2 Pt FcPPAl cpd

FcPPAl Pt dimer

FcPPAl Pt CO cpd

FcPPAl PtH2 cpd

A Borane-Appended Analogue of DPPF and its Platinum Complexes

We recently prepared a borane-appended analogue of dppf (dppf is a wide bite-angle bis-phosphine ligand used extensively in late transition metal catalysis). The ligand, FcPPB:

FcPPB ligand

The FcPPB ligand η3BCC-coordinated to platinum:
FcPPB Pt eta3

The FcPPB ligand η2BC-coordinated to platinum:

FcPPB Pt CO eta2

The FcPPB ligand η1B-coordinated to platinum:

Pt FcPPB CNR eta1

Rhodium Halide and PF6 Complexes of a Borane-Appended Ligand

The borane engages in a tight interaction to chloro or bromo co-ligands. By contrast, (a) there is only a weak interaction between the borane and iodo co-ligand, and (b) a fluoride co-ligand is completely abstracted to generate a zwitterionic complex in which the cationic rhodium center is now η2-coordinated to the ipso and ortho carbon atoms of one of the phenyl rings on boron:


RhI(CO) TXPB 503


When the halide is entirely abstracted from the metal center, the borane engages in an η2BC-interaction with rhodium:


Rhodium-Iron Heterobimetallic Complexes of the TXPB Ligand

Reaction of [RhCl(CO)(TXPB)] with K[CpFe(CO)2] provided [(TXPB)Rh(μ-CO)2Fe(CO)Cp] in which the borane is η3BCC-coordinated to rhodium:


Reaction of [(TXPB)Rh(μ-CO)2Fe(CO)Cp] with isocyanides yields complexes featuring a bridging borataaminocarbyne (C–NR–BR3) ligand:


Palladium Complexes of a Phosphine-Thioether-Borane Ligand

The borane of the TXPB ligand is η3BCC-coordinated to palladium:

Pd TXPB eta3

The TXPB ligand is κ1P-coordinated to palladium (the thioether and the borane are now uncoordinated):

Pd TXPB dvds

One molecule of dba (dibenzylideneacetone) is bound between palladium and the borane of the TXPB ligand. The resulting complex is best described as a zwitterionic boratoxyallyl complexes in which the allyl unit is η3-coordinated to palladium:

dba Pd txpb

One-electron reduction of [PdCl2(TXPB)] yielded the bright red palladium dimer [{PdCl(TXPB)}2] shown below:

Pd(I) Cl TXPB dimer

Alkyl and Aryl Complexes of Borane-Appended Ligands

Reaction of TXPB with [PtMe2(COD)] provided the complex shown below, [PtMePh(TXPB')], with one phenyl and one methyl group on platinum, and one phenyl and one methyl group on boron.:

PtMePh TXPB'  

Heating [PtMePh(TXPB')] resulted in exchange of the remaining phenyl group on boron with the remaining methyl group on platinum:


In solution, [PtMePh(TXPB')] exists in equilibrium with zwiterionic [PtMe(TXPB-Me)]. Neutral [PtMePh(TXPB')] is trapped by addition of 1 equivalent of P(OPh)3, while zwitterionic [PtMe(TXPB-Me)] is trapped by addition of 2 equivalents of CNXyl:

Pt MePh TXPB' P(OPh)3


Complexes of PS- and PSP-Donor Ligands

The PS- and PSP-ligands in the complexes below are borane-free analogues of our borane-containing TXPB ligand. Our primary interest in these complexes is for comparison of their structures and reactivities with TXPB analogues.





Vinylborane Complexes

This is the first η3BCC-coordinated vinylborane complexes. The first one below binds like an allyl ligand, with extensive delocalization within the BCC core of the ligand. The second one below binds like an alkyl anion with an attached borataalkene group.

VBPh Pt PtBu3

VBPh Ni PPh3 2

This is the first complex of a vinylborane-containing ambiphilic ligand (it was formed in situ via the reaction of [Pt(FcPPB)] with HC2Ph):

FcPPB to vinylborane

Rigid Ligand Thorium Complexes

Neutral thorium dialkyl complexes (in the dibenzyl complex, the hydrocarbyl ligands are η2- or η3-coordinated):



An unexpected adduct between [(BDPP)ThX2] and MeMgX(OEt2) where X = Cl or Br, and BDPP = an NNN-donor pincer ligand):

Th grignard adduct

A rare example of a thorium alkyl cation (the 2nd view shows packing between the cations and B(C6F5)4 anions):

ThBn cation

A cationic thorium alkyl complex coordinated to a molecule of the neutral [(XA2)Th(CH2Ph)2] starting material. The μ-η16-coordination mode in this structure is a previously unknown coordination mode for a benzyl ligand:

Th mu benzyl

A thorium dication formed by double alkyl abstraction. The dictionic metal center is π-coordinated to two PhCH2B(C6F5)3 anions.

Th dication

A very sterically hindered complex featuring two BDPP pincer ligand dianions coordinated to thorium(IV):

Th bdpp 2

Rigid Ligand Uranium Complexes

Uranium(IV) halide complexes of rigid NON- and NSN-donor ligands (2 views of each):

u4 non

u4 nsn

Uranium(III) halide complexes of rigid NON- and NSN-donor ligands (2 views of each):

u3 non

u3 nsn

A representative uranium(IV) alkyl complex of our most commonly used NON-donor pincer ligand, XA2:


Yttrium Complexes

We prepared the first acridanide-backbone pincer ligand (the AIm2 monoanion). However, it was readily cyclometallated in the coordination sphere of yttrium, and then two ligands (the cyclometallated ligand and the intact ligand) are coupled together... The low thermal stability of the complexes stems from the imine donors, not the acridanide backbone...

AIm2 ligand

Y AIm2 AIm2_met

Y AIm2 Aim2Met linked

Interesting Alkali Metal Complexes

Potassium-alkane interactions!!! (these are the first crystallographically characterized main group-alkane interactions):

K2 XAT 3-Me-Pentane

K2XAT toluene
An unexpected adduct between nBuLi and Li2[XAT]:

Li3 XAT nBu

Manganese Alkyl/Allyl Complexes

Volatile and thermally robust mixed alkyl / allyl complexes. Their thermal stability is remarkable given their high spin d5 configuration!

Mn alk allyl dmap

Mn alk allyl

Dimetallic Copper and Zinc Complexes

The complexes below are formed as intermediates in the reactions of [CuL2] (L = N-isopropyl-2-pyrrolylaldimine) with ZnEt2 or AlMe3 to deposit copper metal.


LZnEt dimer