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Utilizing a terphenyl bisanilide ligand, two Dy( iii ) compounds [K(DME) n ][L Ar Dy(X) 2 ] (L Ar = {C 6 H 4 [(2,6- i PrC 6 H 3 )NC 6 H 4 ] 2 } 2− ), X = Cl ( 1 ) and X = I ( 2 ) were synthesized. The ligand imposes an unusual see-saw shaped molecular geometry leading to a coordinatively unsaturated metal complex with near-linear N–Dy–N (avg. 159.9° for 1 and avg. 160.4° for 2 ) angles. These compounds exhibit single-molecule magnet (SMM) behavior with significant uniaxial magnetic anisotropy as a result of the transverse coordination of the bisanilide ligand which yields high energy barriers to magnetic spin reversal of U eff = 1334 K/927 cm −1 ( 1 ) and 1278 K/888 cm −1 ( 2 ) in zero field. Ab initio calculations reveal that the dominant crystal field of the bisanilide ligand controls the orientation of the main magnetic axis which runs nearly parallel to the N–Dy–N bonds, despite the identity of the halide ligand. Analysis of the relaxation dynamics reveals a ca. 14-fold decrease in the rate of quantum tunneling of the magnetisation when X = I ( 2 ). Most notably, the relaxation times were on average 5.6× longer at zero field when the heavier group 17 congener was employed. However, no direct evidence of a heavy atom effect on the Orbach relaxation was obtained as the height of the barrier is defined by the dominant bisanilide ligand. 

The photochemically generated synthesis of a terminal uranium nitride species is here reported and an examination of its intra- and intermolecular chemistry is presented. Treatment of the U( iii ) complex L Ar UI(DME) ((L Ar ) 2− = 2,2′′-bis(Dippanilide)- p -terphenyl; Dipp = 2,6-diisopropylphenyl) with LiNIm Dipp ((NIm Dipp ) − = 1,3-bis(Dipp)-imidazolin-2-iminato) generates the sterically congested 3N-coordinate compound L Ar U(NIm Dipp ) ( 1 ). Complex 1 reacts with 1 equiv. of Ph 3 CN 3 to give the U( iv ) azide L Ar U(N 3 )(NIm Dipp ) ( 2 ). Structural analysis of 2 reveals inequivalent N α –N β > N β –N γ distances indicative of an activated azide moiety predisposed to N 2 loss. Room-temperature photolysis of benzene solutions of 2 affords the U( iv ) amide ( N -L Ar )U(NIm Dipp ) ( 3 ) via intramolecular N-atom insertion into the benzylic C–H bond of a pendant isopropyl group of the (L Ar ) 2− ligand. The formation of 3 occurs as a result of the intramolecular interception of the intermediately generated, terminal uranium nitride (L Ar )U(N)(NIm Dipp ) ( 3′ ). Evidence for the formation of 3′ is further bolstered by its intermolecular capture, accomplished by photolyzing solutions of 2 in the presence of an isocyanide or PMe 3 to give (L Ar )U[NCN(C 6 H 3 Me 2 )](NIm Dipp ) ( 5 ) and ( N , C -L Ar *)U(NPMe 3 )(NIm Dipp ) ( 6 ), respectively. These results expand upon the limited reactivity studies of terminal uranium–nitride moieties and provide new insights into their chemical properties. 

The masked Ti( ii ) synthon ( Ket guan)(η 6 -Im Dipp N)Ti ( 1 ) oxidatively adds across thiophene to give ring-opened ( Ket guan)(Im Dipp N)Ti[κ 2 - S (CH) 3 C H] ( 2 ). Complex 2 is photosensitive, and upon exposure to light, reductively eliminates thiophene to regenerate 1 – a rare example of early-metal mediated oxidative-addition/reductive-elimination chemistry. DFT calculations indicate strong titanium π-backdonation to the thiophene π*-orbitals leads to the observed thiophene ring opening across titanium, while a proposed photoinduced LMCT promotes the reverse thiophene elimination from 2 . Finally, pressurizing solutions of 2 with H 2 (150 psi) at 80 °C leads to the hydrodesulphurization of thiophene to give the Ti( iv ) sulphide ( Ket guan)(Im Dipp N)Ti(S) ( 3 ) and butane.