The trihydride complex [ FeH,(dmpe),] + (dmpe = Me,PCH,CH,PMe,) is best represented as [ FeH (H,) -(dmpe),] +, with the H-H separation in the H, being ca. 0.81 A. The H, can be replaced by N, , CO, MeCN, MeNC and C2H4. The dinitrogen complex [FeH( N, ) (dmpe),] + may be deprotonated to yield the solutionstable, trigonal-bipyramidal species [Fe(N,) (dmpe),], which can be reprotonated by HCI to yield [FeCI,-(dmpe),], N, , H, and NH,. The crystal structures of [FeH(H,)(dmpe),]BPh, and [FeH(N,)(dmpe),]BPh, have been determined.

Reaction of anhydrous metal chlorides and lithium amide at 160-400 "C induces an exothermic reaction with formation of lithium chloride and an amorphous material. Trituration of the product with tetrahydrofuran (THF) followed by thermolysis at 700 "C for 1-2 h results in the formation of crystalline metal nitrides of varying composition (TiN, ZrN, HfN, VN, NbN, TaN, Cr2N, CrN, Mo2N, W,N, Mn, N, and Zn,NJ. Reactions involving iron, nickel, copper and indium chlorides with lithium amide yielded the metallic elements. The reactions of lithium dimethylamide and lithium diisopropyl amide and selected metal chlorides also produced metal nitrides under comparable reaction conditions. The metal nitrides were analysed by powder XRD, microanalysis, magnetic moment measurements, FTlR and SEM/EDXA.

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IntermediateButenynyl complex Scheme 1 a dihydrogenhydrido-complex with an estimated H-H separation of 0.87 A. We have also been able to carry out experiments in solvents other than alcohols, and specifically in acetone, which have yielded observations which lead us to propose a rather different mechanism from that suggested for the bis(alkyny1)-butenynyl conversion. This we describe here. Some of our data have been published in preliminary form.3 (c) In the butenynyl ligand C(52W(5 1) 1.40(4) C(6W(7) 1 .32 1 ( 1 3) C(5 1 W(5) 1.469( 17) C(7)-C(70) 1.38q 14) C(5)-C(6) 1.296( 14) C(70)-C(7 1) 1.466( 18) C( 52)-C( 5 1 )-C( 5 ) 108.6( 1 9) C(S)-C(S)-C( 7) 144.8( 10) Fe-C(5)-C(51) 147.0(9) Fe-C(7W(6) 74.2(6) Fe-C( 5)-C( 6) 69.0(6) Fe-C(7)-C(70) 1 53.5(8) C(5 1)-C(5)-c(6) 144.0( 12) C(6)-C(7)-C(70) 132.3( 10) Fe-C(6W(5) 76.0(7) C(7)-C(70)-C(71) 120.8(11) Fe-C( 6)-C( 7) 68.8( 6) Fielder al. Indeed, the complex [Fe(CCMe)(CCHMe)(dmpe),]-BPh, D in acetone shows a singlet in its 31P-{1H) NMR spectrum at 6 -82.5, and [Fe(CCPr')(CCHPr')(drnpe),]-BPh, E a singlet at 6 -86.7. This compares with a value of ca. 6 -82, suggested by Field et al. for these species (never isolated).

Metal nitrides are hard, durable refractory materials with a number of applications, including wear resistance, reflective coatings, and catalysts. Low‐energy approaches to the synthesis of these materials are a topic of current research. A new method for the preparation of tantalum nitride is presented which is a solid‐state reaction, a hybrid between the molecular precursor approach and a metathesis reaction.