Transition metal is covalently bonded to hydrogen in transition metal hydrides which generally have a formulation of the type MH_xL_y where M = transition metal and L = carbon monoxide CO, organophosphine R₃ P, cyclopentadieno C₅H₅^-. etc., type of ligands which can act both as o-donor as well as π- acceptor ligands* M   : L Besides being covalent , the transition metal-hydrogen bond is longer than normal. Some examples of these hydrides are :

K₃ [ H-Co(CN)₅ ], (C₅H₅)₂MoH₂, (C₅H₅)₂Re-H, (Et₃ P)₂(CI)Pt-H, HMn(CO)₅

Preparation of Transition metal hydrides

Transition metal hydrides are not many in number. Some of the important ones are prepared as follows:

(i)     MOCI₅ + 3NaC₅H₅** + 2NaBH₄   →   (C₅H₅)2MoH₂ + 5NaCI + B₂H₆ + 1  C₁₀H₁₀
                                                                                                                                        2
(ii)   (C₅H₅)Fe(CO)₂CI + NaBH₄    →     (C₅H₅)Fe(CO₂)H + NaCI + BH₃
(iii)          Pt(PR₃)2 CI₂ + LiAIH₄       →     (PR₃)₂Pt(CI)H + LiCI + AIH₃

Prosperities of Transition metal hydrides

Most of these compounds are very reactive solids. For example, (C₅H₅)₂ MoH₂ reacts with chloroform t form dichloro derivative.
                        
                           CHCI₃
(C₅H₅)₂ MoH₂    →     (C₅H₅)2MoCI₂ .
(R₃P)₂Pt(CI)H reacts with ethylene to form ethyl derivative.
(R₃P)₂(CI)Pt-H + C₂H₄   →    (R₃P)₂ (CI)Pt-C₂H₅

For more help in Transition Metal Hydrides click the button below to submit your homework assignment